1. Strategic Issues

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ROAD TUNNELS MANUAL

1. STRATEGIC ISSUES

All rights reserved. © World Road Association (PIARC).



PIARC ROAD TUNNELS MANUAL © PIARC

1. Strategic issues

Tunnels, initially aimed at crossing an obstacle (in general a mountain), have become increasingly

complex during recent years, incorporating increasingly complex equipment (including ventilationsystems) and methods of operation. Such operation includes the deployment of control and supervisionsystems that able to handle tens of thousands of items to be controlled, and which can accommodateincreasingly sophisticated management scenarios.

Following the catastrophes at the Mont Blanc, Tauern and Gothard tunnels in the years 1999and 2001, the need for recognising all aspectsrelating to safety as a holistic system wasreinforced. This resulted in the integration, fromthe design of the works onwards, of moreconstraining provisions, which have animportant impact on the required civil

engineering and the specified tunnel equipment.

Tunnels are in general considered as "expensiveand risky" works, both with regards to theirconstruction as well as their operation. This

Figure 1.0 : St Gothard tunnel fire

"image" makes some countries very reluctant when considering the construction of their first tunnel fortheir road or railway infrastructure. In order to address such concerns, it is inevitable that the costs of construction and operation, the control of risks (mainly during the construction phase), the minimisationof accidents or fires during the operation and the optimisation of the tunnel facilities at each stage of thedesign, construction and operation become increasingly necessary.This control of the risks and the costs isreinforced when considering current procurement and financing models for the construction of tunnels,which are increasingly being implemented as "Concession", "Design and Build" or "Private Public

Partnership" models.

Chapter 1 of this manual has the following aims:

to make the reader aware of the "complex system" that a tunnel comprises;

to highlight the importance of the definition of the "function" of the facility for both the upstream(design) and downstream (operational) aspects of the design;

to draw the attention of the tunnel owner to the need for surrounding himself with multidisciplinarycompetences with skills and in-depth experience to ensure the success of the mission;

to make the reader aware that a tunnel is essentially designed to be used in conditions of comfortand safety, and that it must be the subject of continuous and reliable maintenance by the operator.

The concept of a tunnel must take into account these safety and operational objectives and

constraints; and finally to make the reader understand that the facility itself constitutes only a part of the

problems which the owner will have to solve, and that very often it will be necessary to develop inparallel certain external elements which may be outside the tunnel owner’s authority: regulation,intervention and safety services, procedures, etc.

It is not the intention for Chapter 1 to be a detailed handbook of the actions required by tunnel owners, orto specify the technical provisions to be implemented by the designers, or to determine the tasks to betaken by the operators to ensure a safe and comfortable tunnel. In particular, Chapter 1 does not have anobjective to be a handbook of design. Its only objective is to make the reader aware of certain issues, inorder to facilitate his approach and comprehension of this complex field, to hopefully enable him to avoidthe many possible errors in tunnel operations, and to enable him to perceive the possibilities of

optimisation.

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Section 1.1 presents the "complex system" that a tunnel is, and lists the main interfaces of the varioussubsets Civil Engineering, Ventilation and Safety;

Section 1.2presents the major elements which have to be considered when designing a tunnel;

Section 1.3concerns the upgrading and the refurbishment of existing tunnels under operation;

Section 1.4analyses various stages of the cycle of construction and the life cycle, and underlines the key

actions of each one of these phases;

Section 1.5 explains issues relating to the costs of construction, operation and renovation, as well as themain stakes specific to the modes of financing;

Section 1.6gives a list of the main recommendations, instructions and regulations published by a numberof countries in Europe and in the world.

Contributors

This document was compiled by Bernard Falconnat (Egis, France), French representative in the Road Tunnels Operation Committee and member of Working Group 5, which has also translated his French

version into the present English version.Its original version in French was revised by Didier Lacroix (France) and Willy De Lathauwer (Belgium – ITA representative within the committee).

The English version has been reviewed by Lucy Rew (Egis, France) andFathi Tarada (UK).

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1.1. Tunnel is a complex system

1.1.1. Complexity of the system

A tunnel constitutes a "complex system" which is the result of the interaction of very many parameters. These parameters can be gathered by subsets, the principal ones of which are represented on the graphbelow (fig. 1.1-1).

All these parameters are variable and interactive, within each subset, and between the subsets themselves.

The relative weighting of the parameters and their character varies according to the nature of each tunnel.For example:

the determining criteria and the weighting of parameters are not the same for an urban tunnel and amountain tunnel;

the parameters differ for short and long tunnels, for tunnels passed through by vehicles transportingdangerous goods and for those transporting passenger vehicles only;

the criteria are not the same for a new-build tunnel or a tunnel to be refurbished or upgraded to put

it in conformity with new standards concerning safety.

Fig. 1.1-1 : Sketch of main subsets of the "complex tunnel system"

Note 1: the links are multiple and often reversible - the general concept of the tunnel and the functionalsection are placed in the centre of the figure. Similar diagrams could be drawn up while placing otherfactors in the centre of the figure.

Note 2 : the first circle represents "technical fields". Some fields represent multiple aspects:

safety: regulation - risk analysis - intervention means - requirement of availability,





geology: geology - geotechnics - structural dimensioning, civil works: methods - construction schedule - risks and hazards, operation: operation and maintenance (technical aspects), costs: construction - operation - daily maintenance - major repairs, environment: regulation - diagnosis - impact assessment - treatment and mitigation,

Note 3: the second circle represents the "context" in which the project is to be developed. Some elements

represent multiple aspects:

human environment: sensitivity - urbanisation - presence of buildings or infrastructure, natural environment: sensitivity - water - fauna - flora - air quality - landscape, nature of the transport: nature and volume of the traffic - typology - types of goods that are

transported - etc. various external constraints: accesses and particular constraints - climatic conditions - avalanches

- stability of the ground - socioeconomic context - etc. level of profitability: economic acceptability - capacity of financing - control of the financial costs -

general economic and political context in case of concession or Public Private Partnership (PPP).

The design of a new tunnel (or the refurbishment and upgrading of an old tunnel) requires these numerousparameters to be taken into account. The decision tree relating to these parameters is complex, andrequires the input of experienced multidisciplinary parties. They must intervene as early as possible, forthe following reasons:

to enable all relevant parameters to be considered from project commencement, and to avoidnumerous potential pitfalls noted in projects in progress or in recently completed tunnels. Sucherrors include the late consideration of the required equipment for operation and safety, and thedevelopment of a supervision system without integrating the results of the risks analyses, theemergency response plan or the operation procedures.As a consequence, the tunnel and its systemsand equipment for operation and supervision may be inappropriate for safe and reliable operation.

an early intervention contributes to a better optimisation of the project, both from the perspective of safety as well as for construction and operation costs. Recent examples indicate that transverseoptimisations (civil engineering - ventilation - safety evacuation) made at early project stages can

contribute about 20% towards cost savings.

Each tunnel is unique and a specific analysis has to be developed, while taking into account all thespecific and particular conditions.This analysis is essential to bring suitable answers and to allow:

optimisation of the project from a technical and financial aspect; reduction of the technical, financial and environmental risks; guaranteeing the required level of safety for tunnel users.

There is no "magic key solution", and a simple "copy and paste" process is almost always unsuitable.

The design and optimisation of a tunnel require:

an exhaustive and detailed inventory of all the parameters,

an analysis of the interactions between parameters,

the evaluation of the degree of flexibility of each parameter, and if necessary of the sensitivity of each one of them with respect to the required objectives,

a holistic approach to achieving success, because:- a purely mathematical approach is not possible, owing to the fact that the "system" is toocomplex, and there is no single answer;- too many parameters are still unspecified or variable during the early stages of a project, butessential choices still have to be made;- the evaluation of the risks, their gravity and their likelihood of occurrence must be taken intoaccount;- many parameters are interdependent and many interactions are circular.

Several examples are given in the following paragraphs making it possible to clarify the complexity, theinteractivity, as well as the iterative and "circular" character of the analysis.





These examples are not exhaustive. Their aim is simply to make the reader aware of the issues and makeit possible to focus considerations on each specific tunnel.

1.1.2. Subset "Civil Engineering"

1.1.2.1. Parameters

Table 1.1-2 below gives an example of the principal parameters concerning the aspects relating to civilengineering:

Table 1.1-2 : Main parameters according to civil engineering The first column of the table indicates the principal sets of parameters,





The second column of the table indicates the principal subsets of parameters relating to a principalset,

The third column lists a certain number of elementary parameters relating to a subset. The list is notexhaustive,

The fourth column of the table indicates by set, or subset, the principal outcomes related to thesubset.

1.1.2.2. Interactions between parameters

The interactions between parameters are numerous and often connected by circular links taking intoaccount the overlaps between the various parameters.

The example below (Table 1.1-3) relates to the interactions between ventilation, the cross section, andsafety:

The first column concerns ventilation. The parameters listed in this column are the elementaryparameters resulting from table 1.1-2 above for the subset "ventilation",

The second column concerns the cross section. The parameters result from table 1.1-2, The third column concerns safety.

Table 1.1-3 : Interactions between parameters

The figure reveals a certain number of parameters common to several columns (see line connectors),which create circular interactions between the various subsets of parameters. These interactions are linkedby complex functions, which make a purely mathematical resolution of the problem nearly impossible.

The resolution of the problem requires the definition of a hierarchy between the various parameters,followed by taking into account assumptions for the parameters of higher hierarchy. This hierarchy differs

from one project to another, such as for example:





For a short bored tunnel or a medium-length bored tunnel with one-way traffic, the most probableventilation system is "longitudinal ventilation". The jet fans fixed in the crown have indeed usuallya very low impact on the dimension of the cross-section. This one could thus be dimensionedinitially before designing the ventilation, but by taking into account the other determiningparameters. The impact of the ventilation on the cross-section will then be checked afterwards,

Conversely, if the tunnel is very long or the cross-section is rectangular (cut and cover), the

ventilation system and its components (section, number and nature of the possible air ducts -dimension of the jet fans if required - etc.) have an essential impact on the cross-section size. Theventilation system will have to be pre-dimensioned at the beginning of the analysis by makingpreliminary assumptions of the dimension of the cross section. The geometry of the cross-sectionwill then be checked.

The process of resolution is then iterative and based on a first set of assumptions, as the previousexamples show. This process requires a large transverse multi-technical experience of the engineers,making it possible to take into account the relevant parameters for the project, to better target thesuccessive iterations, and to guarantee the best optimisation of the project, with the required level of service and safety.

1.1.3. Subset "Ventilation"

Table 1.1-4 below gives an example of the principal parameters concerning the aspects relating toventilation. This table is not exhaustive.

As for "civil engineering", the interactions between parameters are numerous. They also are subject tocircular relations.

The process to solve the problems is similar to the one outlined above for "civil engineering".





Table 1.1-4 : Main parameters influencing ventilation

1.1.4. Subset "Operation equipment"

They do not constitute fundamental parameters for the definition of the functional section, with theexception of:

box-outs and sleeves for the passage of cables, pipes for water supply to the fire fighting system,




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signalling, signage for information, safety or police instructions. Signalling may have sometimes(rectangular cut and cover) a very important impact on the geometry (distance between roadwayand soffit with a possible impact on the vertical alignment and the tunnel length). This mayeventually require a more global optimisation, which may concern the position and/or the design of the interchanges outside the tunnel close to the portals.

"Operation equipment" constitutes on the other hand essential parameters for the dimensioning of the

technical buildings at the portals, of underground M&E sub-stations, and of all underground technicalspaces, or various provisions, recesses and niches. They often require particular arrangements concerningtemperature, air conditioning, and air quality.

They also are important parameters in terms of cost: construction, operation and maintenance.

"Operation equipment" constitutes essential parameters regarding tunnel safety. It must be designed, builtand maintained in this objective:

availability and reliability, in particular power supply and distribution, as well as all thecommunication networks,

protection against fire of all equipment, in particular of the main power supply cables and the cablesof the transmission networks,

hardiness of the equipment and its components in order to guarantee its life-span, reliability andoptimisation of costs: operation and maintenance,

to facilitate maintenance interventions, their low impact on the traffic conditions, as well as on thesafety of the maintenance teams and the users, which requires particular arrangements concerningthe design and the accessibility of these facilities,

integration of the procedures for operation, and the emergency response plan in the design of thesupervision system (SCADA), the ergonomics of the man/machine interfaces, and assistance to theoperator in particular during an incident.

1.1.5. Subset "Safety"

1.1.5.1. Concept "Safety" The conditions of safety in a tunnel result frommany factors as presented in chapter 2 of thisManual.It is necessary to take into account allthe aspects of the system formed by theinfrastructure itself to ensure safety as well as itsoperation, interventions, vehicles and users (Fig.1.1-5).

Fig. 1.1-5 : Factors affecting safety

Infrastructure is an essential parameter of construction cost. However, one can investhighly in infrastructure without improving

conditions of safety if essential provisions arenot considered in parallel concerning:

organisation, human and material means, the procedures of operation and intervention, training of operating staff, the emergency services' equipment with efficient material and training of their staff, communication with users.

1.1.5.2. How do these parameters affect a tunnel project?

These parameters relating to safety may affect in a more or less important way a tunnel project. The tablesbelow give some examples.

Note: The four tables below refer to the four principal fields represented in Fig. 1.1-5.

Column 1 indicates the principal infrastructure or actions concerned,

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Columns 2 and 3 indicate the degree of influence on the tunnel project (civil engineering -ventilation - operating and safety equipment):

Green: important or major impact Yellow: medium impact, Red: no impact.

Column 4 specifies the main reasons or causes of influence.

Fig. 1.1-6 : Main impacts on the project due to infrastructure

Fig. 1.1-7 : Main impacts on the project due to intervention conditions and the organisation of the operation

Fig. 1.1-8 : Main impacts on the project due to vehicles

Fig. 1.1-9 : Main impacts on the project due to the tunnel users

1.1.6. Synthesis

A tunnel is a "complex system" which means in particular that:

approaching the design of a tunnel from the point of view of only the alignment, the geology or thecivil engineering, leads to serious design deficiencies, which are likely to make the tunnel less safe

(possibly even dangerous) and difficult to operate (perhaps impossible to be operated underreasonable conditions).






in the same way, to approach the design of a tunnel from the point of view of only the operatingequipment without integrating an upstream analysis of risks and safety, intervention and operation,will also lead to deficiencies that will very quickly appear as soon as the tunnel is open to traffic,

not taking into account, from the preliminary design stage, all the objectives and constraints relatingto the operation and to the maintenance, will inevitably lead to increased operational costs and toreduced overall reliability.

Partial treatment of problems is unfortunately still rather frequent, due to lack of sufficient "tunnelculture" of the various actors involved in the design.

Control of this complex system is difficult but essential in order to:

find the appropriate solution to each problem, ensure the users have an essential level of safety, and to offer them a service of quality and good

comfort.

In a parallel way the control of this complex system very often contributes to the technical andeconomical optimisation of the project, by a clear and early definition of the functions to be ensured andby using a value engineering process.

Taking into account, from the start of the project, the major issues relative to:

horizontal and vertical alignments, geology, civil engineering construction provisions and methods, ventilation, safety (by a preliminary analysis of risks and danger and a preliminary emergency plan), operation and maintenance conditions,

constitutes an effective approach to solving this complex equation.




1.2. General design of the tunnel (new tunnel)

Section 1.2 relates to the design of new tunnels. The design concerning the refurbishment and the safetyupgrading of tunnels under operation is presented inSection 1.3.

1.2.1 Horizontal and vertical alignment

The design of the horizontal and vertical alignment of a road or highway section, which includes a tunnel,constitutes a major and fundamental first stage in the creation of a new tunnel, to which the necessaryattention is seldom given.

The consideration of the "complex system" which constitutes a tunnel has to start at the early stage of thedesign of the general alignment, which is seldom the case. It is however at this stage that technical andfinancial optimisations are the most important.

It is essential to mobilise from the earliest stage of the design a multidisciplinary team made up of veryexperienced specialists and designers, who will be able to identify all the project's potential problems,

despite inevitably incomplete preliminary information. This team will be able to make good and reliabledecisions for the major choices, and then consolidate these elements progressively taking into account theavailability of additional information.

The objective of this section is not to define the rules regarding tunnel layout design (several countries'design handbooks are referred to in Section 1.6) but essentially to sensitise the owners and the designersto the necessity of a global and multicultural approach, from the early stages of the design, and to theimportance of essential experience that is paramount to the success of the project.

1.2.1.1 Countries without "tunnel culture"

In these countries owners and designers have a certain apprehension about tunnels. They very often prefer"acrobatic road layouts" passing along ridges, with steep gradients, huge retaining walls or very long

viaducts, and sometimes tremendous consolidation works (which are very expensive and not alwayseffective over a long period of time), in order to cross zones with active landslides.

Numerous examples of projects including tunnels and alignment variations designed with a global“system” approach demonstrate, in comparison with approaches refusing systematically the constructionof tunnels:

construction cost savings may reach between 10% and 25% in areas with mountainous conditions, important savings of operation and maintenance costs can be achieved. The reliability of the route

can be improved, in particular in zones of instability or active landslides, or subject to severeclimatic conditions,

environmental impact is significantly reduced, the level of service for the users is improved, and the operating conditions, in particular in winter (in

countries subject to snowfall) are made reliable by the reduction of the gradients required bypassages along ridges.

The assistance of an external assessor makes it possible to mitigate the insufficiency or the lack of "tunnelculture", and to improve the project significantly.

1.2.1.2 Countries having a tradition of construction and operation of tunnels

The concept of "complex system" is seldom integrated upstream, to the detriment of the globaloptimisation of the project. Too often the "geometry" of the new infrastructure is fixed by layoutspecialists without any integration of the whole of the constraints and tunnel components.

It is however essential to take into account from this stage all the parameters and interfaces described inparagraph 1.1 above, and in particular:

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the general geology and hydrogeology of the area (with the available level of knowledge) as well aspreliminary appreciation of the geological difficulties and the potential risks concerning themethods, costs and construction duration,

the potential geomechanical, hydro-geological, hydrographical conditions at the tunnel portals andalong the accesses,

the risks and hazards related to winter conditions for countries subjected to noteworthy snowfall, inparticular:

- the risks of avalanche or formation of snow-drifts and the possibilities of protecting the accessroads and the portals against these risks,

- the maintenance conditions of access roads in case of significant snowfalls to guarantee thereliability of the route. This provision may condition the altitude of the tunnel portals, themaximum slopes of the access roads, and if necessary the place available to arrange surfaces forchaining and unchaining in the vicinity of the portals,

the environmental conditions at the tunnel portals and on the access roads. The impact can besignificant in urban environments (in particular because of the noise and the discharge of pollutedair), as well as for interurban tunnels,

the gradient of the approach ramps:- the least expensive tunnel is not always the shortest tunnel,- the suppression of a special lane for slow vehicles is difficult to manage in the vicinity of a

tunnel portal, and keeping such a lane in a tunnel is generally very expensive,- the gradient of the access roads can have a very strong impact on the capacity of the route in

terms of traffic volume and winter reliability.

the possibility of incorporating adits as lateral accesses (ventilation - evacuation and safety -reduction of the construction works schedule), or as vertical or inclined shafts (ventilation -evacuation and safety),

- these particular access points, their impact on the surface (in particular in urban environments:available space - sensitivity to the discharge of polluted air - etc), their year-round accessibility

(e.g., exposure to avalanches) may constitute important constraints for the design of thehorizontal and vertical alignment. Conversely they very often contribute to the optimisation of the construction and operation costs,

- these particular access points may have a major impact on the construction and operation costs,and on the size of the cross section (potential optimisation of the ventilation and the evacuationfacilities),

the methods of construction which may have a major impact on the design of the horizontal andvertical alignment, for example:

- crossing under a river with a bored tunnel constitutes an essentially different project to that of asolution by immersed prefabricated boxes,

- interfaces with a viaduct at the tunnel portal,

- the imposed construction deadline may have a direct impact on the layout, in particular to allowdriving from both tunnel portals as well as intermediate drives, using adits,

the geometrical characteristics of the layout and the longitudinal profile of the tunnel for which it isalso necessary to integrate the following elements:

- limitation of gradients, which have a major impact on the sizing of the ventilation system andon the reduction of the traffic volume capacity of the tunnel,

- the hydraulic conditions of underground drainage during the construction and the operationperiod, which affect the vertical alignment,

- reduced lateral clearance (construction of additional widths is very expensive) which requireparticular analysis of the visibility conditions and particular vigilance in the choice of the radiiof the curves for the horizontal alignment,

- the best choice of the radii in order to avoid alternating cross-fall slopes, and their major impacton water collecting and drainage systems from the carriageways, interfaces with sleeves for the





installation of cables, water pipes for fire fighting, which can even lead to an increase in thedimension of the cross section,

all usual constraints related to the occupation of the underground space, in particular in urbanenvironments: subways - car parks - foundations - structures sensitive to settlements,

construction and operation costs:- the least expensive tunnel is not necessarily the shortest one,- an additional investment in civil engineering can be overall more economic over the tunnel

lifetime if it enables a reduction of the costs for construction, operation, maintenance and heavyrepairs (in particular ventilation), or if it makes it possible to postpone for several years the dateof traffic capacity saturation (impact of the gradient in the tunnel and on the accesses),

the coordination between the horizontal and the vertical alignments must be carefully studied in atunnel in order to support the level of comfort and safety of the users. The visual effect of thechanges of slopes in the vertical alignment, in particular in high points, is highlighted by the limitedvisual field of the tunnel and by the lighting,

the conditions of operating with uni- or bidirectional traffic have to be taken into account in thedesign of the layout, in particular:

- the usual conditions of visibility and legibility,- the possibility of arranging lateral accesses (adits) or vertical accesses (shafts), in particular for:

optimisation of ventilation and the cross-section, improvement of safety (evacuation of theusers and access of the emergency teams by avoiding the construction of an expensive parallelgallery),

the layout in the vicinity of the portals:- the tunnel portals constitute singular points of transition, and it is necessary to take into account

human behaviour and the physiological conditions. It is essential to preserve a geometricalcontinuity to make it possible for the user to preserve his instinctive trajectory,

- a rectilinear tunnel is not desirable, in particular along the approach of the exit portal. It may benecessary to reinforce the exit lighting over a long distance,

underground junctions at or very close to the tunnel portals:

- interchanges inside a tunnel or outside in the immediate vicinity of the portals are to be avoided,

- if they are unavoidable, a very detailed analysis must be made to determine all the constraintsand particular consequences to be taken into account (layout - cross-section - exit or merginglanes - risk of backward traffic flow - evacuation - ventilation - lighting - etc) to ensure safety inall circumstances.

1.2.2 The functional transverse profile

1.2.2.1 The issues The functional transverse profile constitutes the second major stage of the design of a tunnel afterselecting the alignment. As for the first stage, the "complex system" approach must be taken into accountin a very attentive way, as upstream as possible with an experienced multidisciplinary team. All of theparameters and interfaces described inParagraph 1.1must be considered.

This second stage (functional transverse profile) is not independent of the first stage (alignment), and itmust obviously take into account the resulting provisions. The two stages are interdependent and veryclosely linked together.

Moreover, as mentioned in paragraph 1.1.2.2 above, the process of the first two stages is iterative andinteractive. There is no direct mathematical approach to bring a single response to the "complex system"analysis. There is also no uniqueness of answer but a very limited number of good answers and a great

number of bad answers. The experience of the multidisciplinary team is essential for a good solution to beidentified quickly.







The examples quoted in paragraph 1.2.1 above illustrate that the provisions of the "functional transverseprofile" can have a major impact on the design of the horizontal and vertical alignments.

Experience shows that the analysis of the "functional transverse profile" is very often incomplete andlimited to the sole provisions of civil engineering, which leads inevitably to:

in the best case, a project that is not optimised from the functional, operational and financial points

of view. Experience shows that potential optimisations can reach in exceptional cases 20% of theconstruction costs,

in the most frequent case, an inadequate consideration of the functions, their constraints and theirimpacts on the project. These functions will have to be integrated in the following stages of theproject by implementing late and often very expensive solutions,

in the worst case, fundamental design errors with an irremediable and permanent impact on thetunnel, on its conditions of operation and safety, as well as on its construction and operation costs.

1.2.2.2 Principal provisions

The major parameters of the "functional transverse profile" are as follows:

Traffic volume - nature of the traffic - operation organisation - urban or non-urban tunnel, in order

to determine:- the number and width of the lanes, according to the traffic and the type of vehicles admitted tothe tunnel,

- the headroom (according to the type of vehicle),- the hard shoulder, emergency stopping lane or lay-by, according to the volume of traffic, the

mode of operation, i.e. uni- or bidirectional, the statistical rate of breakdowns,- a possible central separator and its width in the event of bidirectional operation,

Ventilation has a major impact which depends on:- the selected system of ventilation, itself depending on many other parameters (seeParagraph

8.5),- the space required for the ventilation ducts, for the installation of axial fans, jet fans, secondary

ducts, and all the other ventilation equipment,

Evacuation of the users and the access of the emergency and rescue teams which depend on thenumerous factors detailed in Chapter 7,

The length and the gradient of the tunnel. These parameters intervene in an indirect way through theventilation, the concepts of access and safety,

The networks and equipment for operation are also very often determining factors in thedimensioning of the functional cross section, taking into account their number, the space theyrequire, the essential protection associated with them to guarantee the operational safety of thetunnel, and the relatively limited space under the walkways and hard shoulders to locate them. Thefollowing networks are in particular concerned, which have a dimensional impact:

- separated or combined sewer system(s) - collection of polluted liquids from the roadways and

associated siphons. The absence of variation in the crossfall, associated with the conditions of the alignment (see § 1.2.1.2) allow a simplification and an optimisation of the functionaltransversal profile,

- water supply network for the fire fighting system, fire hydrants, and if necessary their protectionagainst freezing,

- all networks of cables of high and medium voltage, as well as low voltage currents. It isessential to take into account on the one hand, the cables necessary at the time of the tunnelopening and their protection against fire, as well as the provisions allowing their partial or totalreplacement, and on the other hand the provisionsfor the inevitable addition of other networksthroughout the tunnel's life,

- the particular needs in the short or medium term for external networks likely to pass through thetunnel,

- all interactions between networks and needs (technical or legal) for spacing between somenetworks,


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- all of the signalling for operation: signalling and signage - lane signals - panels with variablemessages - regulation indications - safety indications - directional indications,

Localised functional interfaces: underground sub-stations - underground ventilation plant - safetyrecesses - shelters - etc. It is essential to take into account the provisions for operation and themaintenance, and in particular the construction of lay-bys for maintenance interventions and the

safety of the operating teams, Construction methods and geological conditions have an impact on the functional transverse section

(independently of the dimensioning of the civil engineering structures), for example:- the underwater crossing mentioned in section 1.2.1.2 above. The solution with immersed

precast boxes enables a very different design and arrangement of the ventilation system, theevacuation galleries or the access of the emergency teams, in comparison with the arrangementfor the same equipment in the case of a bored tunnel,

- a tunnel bored with a TBM (tunnel boring machine) makes surfaces available under theroadway which can be used for example for ventilation, for the users' evacuation, or for theaccess of the emergency services. This can allow optimisations (removal of connection galleriesor a parallel gallery) which can be financially very important if the tunnel is located under

groundwater level in permeable materials.

1.2.3 Safety and Operation

1.2.3.1 General provisions

PIARC's recommendations are numerous in the fields of safety and operation for the finalisation of safetystudies, the organisation of operation and emergencies, as well as the provisions for operation. The readeris invited to refer to theme : see Chapter 2 "Safety" and Chapter 3 "Human factors regarding tunnelsafety").

This present chapter primarily treats safety and operation interfaces within the "complex system". Thetables of section 1.1.5.2 above indicate the degree of interdependence of each parameter compared to thevarious subsets of the project.

A certain number of parameters have a major impact from the upstream stages of the project onward. They must be analysed from the first phases of the design and deal in particular with:

volume of traffic - nature of the traffic (urban, non urban) - nature of vehicles (possibly tunneldedicated to one category of vehicles) - transport or not of dangerous goods,

evacuation of the users and access of the emergency teams, ventilation, communication with the users - supervision system.

These major parameters for the design of the tunnel are also the essential factors of the "hazard analysis",and drafts of the "intervention plan of the emergency teams". This is why we consider that it is essential

that a "preliminary risk analysis", associated with a preliminary analysis of an "emergency response plan"should be carried out in the initial stages of the preliminary design. This analysis makes it possible tobetter describe the specific features of the tunnel and the functional and safety specifications which itmust satisfy. It also contributes to a value engineering analysis, to a better design and to the technical andfinancial improvement and optimisation.

These parameters and their impacts are detailed in the following paragraphs

1.2.3.2 Parameters relating to the traffic and its nature

These parameters have an impact mainly on the functional cross-sectional profile (See 1.2.2), and throughit a partial impact on the layout:

the volume of traffic affects the number of lanes, ventilation and evacuation. It also affects theimpact of breakdown vehicles and their management when stopped: requirement for a lateralstopping lane or not, for lay-bys, and organisation of particular provisions for repair service,


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the nature of the traffic, the type of vehicles and their distribution affect the evacuation concept(cross-passages, evacuation galleries, their dimensioning, their spacing) according to the volume of people to be evacuated,

tunnels dedicated to particular categories of vehicle relate to the width of the lanes, headroom andventilation,

the passage or not of dangerous goods has an important impact on the ventilation system, the"functional cross-section", fluid collection and dewatering measures, diversion routes, theenvironment of the tunnel portals or ventilation stacks, the protection of the structures against theconsequences of a major fire, as well as on evacuation and the organisation of the emergencyservices and the provision of the fire brigade in specific means and material.

1.2.3.3 Evacuation of the users - access of the emergency teams

This is a fundamental parameter concerning the functional provisions and the general design. Thisparameter also often affects the alignment (direct exits to outside) and construction provisions: cross-passages - under gallery - parallel gallery - shelters or temporary refuges connected to a gallery.

Its analysis requires an integrated approach with the ventilation design (in particular the ventilation in caseof fire), volume of traffic, risk analysis, drafting of the emergency response plan (in particular

investigation of the scenarios ventilation / intervention) and construction methods.

It is necessary from a functional point of view to define the routes, their geometrical characteristics andspacing in order to ensure the flow of able-bodied and disabled people.

It is essential to insure the homogeneity, the legibility and the welcoming and calming character of thesefacilities. They are used by people in situations of stress (accident - fire), at the self-rescue stage (beforethe arrival of the emergency services). Their use has to offer a natural, simple, efficient and calmingcharacter in order to avoid the transformation of the state of stress into a state of panic.

1.2.3.4 Ventilation

Ventilation facilities designed as a pure "longitudinal ventilation" system have little impact on the"functional cross section" or on the "alignment".

This is not the case for "longitudinal ventilation" facilities equipped with a smoke extraction duct, or for"transverse ventilation" systems, "semi-transverse" or "semi-longitudinal" systems, "mixed" systems, orfor ventilation systems including shafts or intermediate galleries permitting to draw or to discharge airoutside other than at the tunnel portals. All these facilities have a very important impact on the "functionalcross section", the "alignment" and all the additional underground structures.

The ventilation facilities of the traffic space are essentially designed in order to : provide healthy conditions inside the tunnel by the dilution of air pollution in order to keep the

concentrations to a level lower than those required by the recommendations of national regulations, ensure the safety of the users in case of fire inside the tunnel, until their evacuation outside of the

traffic space, by providing efficient smoke extraction,

The ventilation facilities may also provide additional functions: limitation of air pollution at the tunnel portals, by improved dispersal of the polluted air, or by

cleaning the air prior to its discharge outside the tunnel, underground plants for cleaning the polluted air in order to reuse it within the tunnel. These

facilities exist in urban tunnels or in very long non-urban tunnels. They are complex and expensivetechnologies, requiring a lot of space and considerable maintenance,

in case of fire, to contribute to limiting the temperature inside the tunnel in order to reduce thedeterioration of the structure by thermal effects.

The ventilation facilities do not only concern the traffic space. They also concern: the connection galleries between the tubes, the evacuation galleries or the shelters used by the users in case of fire,





the technical rooms or plants situated inside the tunnel or outside near the tunnel portals that mayrequire air renewal, or management and control of the temperature level (air heating or conditioningaccording to the geographical conditions).

The ventilation facilities have to be designed in order to be able to:

adapt in a dynamic and fast way to the numerous conditions and capacities in which they areoperated in order to face :

- climatic constraints, in particular significant and fluctuating differentials of pressure betweenthe portals for long tunnels in mountainous areas,

- variable operating rates for smoke management in case of fire, according in particular to thedevelopment of the fire, then its regression, as well as throughout the fire period in order to besuited to the evolution of the fire fighting strategies at each stage of evacuation, of fire fighting,of preservation of the structures, etc.

present enough development capacity in order to be able to adapt throughout the tunnel's life to theevolution of the traffic (volume - nature), lowering of the admissible pollution levels and variousconditions of operation.

1.2.3.5 - Communication with the users - supervisionCommunication with users has an important impact on the "functional transverse profile" throughsignalling.

The other major impacts do not relate to the whole of the "complex system". They relate to the subsystemconcerning the operating equipment, in particular remote monitoring, detection, communications, trafficmanagement, control and supervision, as well as the organisation of evacuation.

1.2.3.6 - Particular requirements for operation

The operation of a tunnel and the intervention of the maintenance teams may require particulararrangements in order to enable interventions under full safety conditions, and to reduce restrictions to thetraffic.

These arrangements concern for example the provision of lay-bys in front of the underground facilitiesrequiring regular maintenance interventions, accessibility to materials for their replacement andmaintenance (in particular heavy or cumbersome material).

1.2.4 The operating equipment

The objective of this section is not to describe in detail operation facilities and equipment, their functionor their design. These elements are defined in the recommendations of the current "Road TunnelsManual", as well as in the handbooks or national recommendations listed in section 1.6 below.

The objective is to draw the attention of owners and designers to the particular issues peculiar to the

equipment and the facilities of tunnel operation.1.2.4.1 Strategic choices

The operating equipment must allow the tunnel to fill its function, which is to ensure the passage of traffic, and to satisfy the double mission of providing for the users a good level of comfort and safetywhen crossing the tunnel.

The operation facilities must be suited to the function of the tunnel, its geographical location, its intrinsicfeatures, the nature of the traffic, the infrastructures downstream and upstream of the tunnel, the majorissues relating to safety and to emergency organisation, as well as the regulation and the cultural andsocioeconomic environment of the country in which the tunnel is situated.

A plethora of operation facilities does not automatically contribute to the improvement of the level of

service, comfort and safety of a tunnel. It requires increased maintenance and human intervention, which,if not implemented, may lead to a reduction in the reliability of the tunnel and its level of safety. The





juxtaposition or the abuse of gadgets is also useless. The facilities must be suited, complementary,sometimes redundant (for the essential functions of safety), and have to form a coherent whole.

The facilities of operation are "living":

They require a rigorous care and maintenance regime, recurrent and suited to their level of technology. This maintenance has a cost and requires skilled human resources, as well as recurrentfinancial investment throughout the tunnel's life. Lack of maintenance (or insufficient maintenance)leads to major dysfunctions, to the failing of the facilities, and as a consequence to the calling intoquestion of the tunnel's function and the users' safety. Maintenance of the facilities under trafficconditions is often difficult and very restricted. Arrangements must be considered from the designof the facilities. For this reason the "architecture" of the systems, their design and their installationhave to be thought out in order to limit the impact of the dysfunctions on the availability and thesafety of the tunnel, as well as the impact of the maintenance interventions or the renovation of thefacilities,

Their "life span" is variable: about ten to thirty years according to their nature, their hardiness, theconditions to which they are exposed, as well as the organisation and the quality of themaintenance. They must therefore be replaced regularly, which requires adequate financing,

Technological evolution often makes essential the replacement of facilities that include advancedtechnologies, because of technological obsolescence and the impossibility of obtaining spare parts, The facilities must show evidence of adaptability to take into account the evolution of the tunnel

and its environment.

All these considerations lead to strategic choices of which the main ones are:

To define the necessary facilities according to the real needs of the tunnel, without yielding to thetemptation of accumulating gadgets. Risk analysis combined with value engineering is a powerfultool allowing the rationality of the choice of the necessary facilities. This approach also allows tobetter master the complexity of the systems, that is often a source of delays, cost over-runs andmajor dysfunctions if this complexity has not been managed by a rigorous and competentorganisation,

To give priority to the quality and the hardiness of the equipment in order to reduce the need andfrequency of maintenance and the difficulties of intervention under traffic conditions. This canresult in a higher investment cost but is compensated very extensively during the operation period,

To verify the quality and the performance of the facilities at each stage of the design, manufacture,factory acceptance tests, installation on site and then site acceptance tests. Experience shows thatnumerous facilities are deficient and do not satisfy the objectives because of lack of rigorousorganisation and efficient controls,

To choose technologies suitable to the climatic and environmental conditions, which the facilitieswill have to face, as well as to the socio-cultural conditions (deficiency of the maintenance conceptin some countries), and to technological and technical conditions, as well as to the organisation of the services,

To take into account, from the design of the facilities and the choice of the equipment, the operationcosts and in particular energy costs. These costs are recurrent throughout the tunnel's life.Ventilation and lighting facilities are in general the highest consumers of energy. Particularattention must be drawn to this aspect from the preliminary design stages,

To take into account from the preliminary stages of design and financing analysis:-the necessity to implement, to organise, to learn and to train teams dedicated to operation andintervention on the one hand, and on the other hand to cleaning and maintenance,-the constraints of intervention under traffic conditions for maintenance,resulting operation,maintenance and refurbishment costs,

To take into account in the general organisation and scheduling of a new tunnel project, the time

required to recruit the teams and to train them, for tests, as well as the "dry run" of all the facilitiesand systems (period of 2 to 3 months), for practices and manoeuvres on site with all the external





intervening parties (in particular emergency services - fire brigade) in order to familiarise them withthe particularities of the tunnel.

1.2.4.2 - K ey recommendations concerning the main facilities

1.2.4.2.a Energy - sources of power - electric distribution

For the tunnel equipment to function there must be a power sources. Large tunnels can require a power of several MW (megawatts), which may not always be available on site. Particular arrangements must betaken from the first stages of the design in order to strengthen and make more reliable the existingnetworks, or often to create new networks. The power supply is essential for the operation of the tunnel. Itis also essential for its construction.

The supply of electric energy and its distribution inside the tunnel must provide:

the required capacity, a reliable supply, a reliable, redundant and protected energy distribution system: redundancy and interconnectionof

the distribution networks - transformers in parallel - cables located inside sleeves and in manholesprotected against the fire.

Every tunnel is specific and has to be subjected to a specific analysis according to its geographicalposition, the context of the existing electrical networks, the energy supply conditions (priority or notpriority), the possibility of increasing or not the power and the reliability of the existing public networks,the risks peculiar to the tunnel, as well as the conditions of intervention of the emergency services.

The facilities must be then designed consequently, and the operating procedures must be implementedaccording to the reliability of the system and the choices that have been taken during the design period.

The objectives concerning safety, in case of a power supply cut are:

immediate emergency supply without interruption of all of the following safety equipment during aperiod of about half to one hour (according to the tunnel and the evacuation conditions) :

- minimal lighting level - signalling - CCTV monitoring - telecommunications - data transmission

and SCADA - sensors and various detectors (pollution - fire - incidents - etc.),- power supplies to safety niches, evacuation routes and shelters,- this function is usually ensured by UPS systems, or diesel generators immediately able to

supply energy,

varying from tunnel to tunnel, its urban or rural location and the risks incurred, additional objectivesof MOC (Minimal Operation Conditions) can be set to assure the electrical supply of the followingequipment, as long as specific procedures are implemented during the whole duration of the powercut. For example: emergency power supply of the ventilation system (by generators or a partialexternal supply) permitting the tackling of light vehicle fires, but not truck fires: the passage of trucks is then temporarily forbidden.

The arrangements usually implemented for the electrical power supply are as follows:

Emergency power supply from the public network:- 2 to possibly 3 supplies from the public network grid with connections to independent segments

of the high voltage or middle voltage network. Automatic switching between "normal supply"and "emergency supply" inside the tunnel power substation with, if required, interruption of thepower supply to some of the equipment, if the emergency external power supply is insufficient,

- no diesel generators,- installation of a UPS emergency power supply.

No external emergency power supply:- a single external power supply from the public network,- diesel generators able to provide a part of the power in case of interruption of the main external

power supply, and setting up of MOC and particular operating procedures,- installation of a UPS emergency power supply.





Full autonomy of the power supply - no external power supply available:- the public network is not able to provide the required power, or does not have the required

reliability. The tunnel is then in complete autonomy. The energy is entirely provided by a set of diesel generators working simultaneously. An additional generator is installed as "back up" incase one of the generators should fail,

- possible installation of a UPS emergency power supply, if the level of reliability of thegenerators is considered insufficient, or for safety reasons.

1.2.4.2.b Ventilation

PIARC recommendations are numerous in this field and constitute the essential international referencesfor the conception and the design of ventilation facilities.In addition to section 1.2.3.4 above, the readershould refer toSection 8.5.

However, it must be remembered that even if the ventilation equipment constitutes one of the essentialfacilities in assuring the health, comfort and safety of the users in a tunnel, it is only one of the links of thesystem, in which the users, the operators and the emergency and rescue teams constitute the mostimportant elements by their behaviour, their expertise and their capacity to act.

The ventilation facilities alone cannot deal with all scenarios, nor satisfy all the functions that might beassumed, especially concerning air cleaning and the protection of the environment.

The relevance of the choice of a ventilation system and its dimensioning requires lengthy experience, theunderstanding of the complex phenomena of fluid mechanics in an enclosed environment, associated withthe successive stages of the development of a fire, the propagation, radiation and thermal exchanges, aswell as the development and the propagation of toxic gases and smoke.

The ventilation facilities are in general energy-consuming and particular attention must be paid to theoptimisation of their dimensioning and their operation, by using for example expert systems.

The ventilation facilities may be very complex, and their relevant management in case of fire may requirethe implementation of automated systems that allow to manage and master the situation more efficientlythan an operator under stress.

As indicated in section 1.2.3.4 above, the ventilation facilities must above all satisfy the requirements forhealth and hygiene during normal conditions of operation, and to the objectives of safety in case of fire.

Hardiness, reliability, adaptability, longevity and optimisation of energy consumption constitute majorquality criteria that the ventilation facilities must satisfy.

1.2.4.2.c Additional equipment to the ventilation facilities

Two types of additional equipment for ventilation are often the subject of pressing demands fromstakeholders, resident associations or lobbies:

Air treatment or air cleaning facilities, Fixed fire suppression systems.

A. Air cleaning facilities. Section 5.1deals with this question and the reader is invited to refer to it.

The implementation of air cleaning facilities is a recurrent demand of resident protection associations inurban areas. These facilities, usually installed underground, are very expensive to construct as well as tooperate and maintain. They are also high consumers of energy.

Results to date are far from convincing, due in particular to important emission reductions from thevehicles, and to the difficulty for these systems to clean the very low concentrations of pollutants that arein the tunnel, contained in large volumes of air. Consequently, many systems installed in the last ten yearsare no longer operational.

The future of air cleaning facilities is very uncertain in countries where there is more coercive regulation,imposing more and more rigorous reductions of polluting emissions at the source.

B. Fixed fire suppression system (FFSS). Section 8.7 deals with this issue, and the reader is invited torefer to it.



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The technologies are numerous and answer to varied criteria: fire fighting - containment of the fire -reduction of thermal radiation and temperature for the users situated in the vicinity of the fire -preservation of the tunnel structure against damage due to high temperature, etc.

These systems, even though presenting positive aspects, also present negative aspects related in particularto the deterioration of the conditions of visibility if they are activated from the start of the fire. The use of

an FFSS requires a coherent approach to all aspects of the users' safety, as well as to ventilation andevacuation strategy.

The decision concerning the implementation or not of such systems is complex and has importantconsequences. It must be subject to a thorough reflection relating to the particular conditions of safety of the work concerned and to the added value obtained by the implementation of the system. It should not betaken under the influence of fashion or a lobby.

The FFSS requires the implementation of important maintenance measures, the carrying out of regularand frequent tests, without which its reliability cannot be assured.

1.2.4.2.d Lighting

The recommendations of the CIE (International Commission for Lighting) have been criticised by PIARC

because of the high levels of lighting to which they often lead. The reader is invited to refer to thetechnical report published by the European Committee of Normalization that presents several methodsincluding the CIE's.

Lighting is a fundamental tool to ensure the comfort and safety of the users in a tunnel. The objectives of the lighting level must be adapted to the geographical location of the tunnel (urban or not), its features(short or very long), to the volume and nature of the traffic.

Lighting equipment consumes a lot of power and developments are in progress to optimise their featuresand performance.

1.2.4.2.e Data transmission - Supervision - SCADA

SCADA is the "nervous system" and the "brain" of the tunnel, permitting the compilation, transmission

and treatment of information, and then the transmission of the equipment's operating instructions.

This system requires a meticulous analysis according to the specific conditions inside the tunnel, itsfacilities, the organisation and the mode of operation, the context of risks in which the tunnel is placed, aswell as the arrangements and procedures implemented for interventions.

The organisation of the supervision and control centre has to be analysed very carefully, according to thespecific context of the tunnel (or of the group of tunnels), the necessary human and material means, themissions to be assumed, the essential aid brought by the automatic devices or the expert systems to theoperators in event of an incident, allowing the operators to reduce and simplify their tasks and to makethem more efficient.

The detailed design of these systems is long, delicate and requires a very rigorous methodology of

developing, of controlling by successive stages (in particular during factory tests), of testing, of globallycontrolling after integration of all the systems on site. Experience shows that the numerous errors noted onthese systems come from the following gaps:

badly defined specifications, insufficient functional analysis, or ignorance of operational conditionsand procedures,

late systems development, which does not allow the time necessary for detailed analyses, transverseintegration, or to take into account the peculiar conditions of operation of the tunnel,

lack of rigour in the development, testing, control and integration of all of the systems, lack of taking into account human behaviour and general ergonomics, lack of experience in tunnel operation, in the hierarchy of the decisions that are to be integrated and

the logical sequences of these decisions in the event of a serious incident.

Section 8.2of the manual sums up these different aspects.


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1.2.4.2.f Radio-communications - low voltage circuits

These facilities include:

emergency phone network, radio network for the operation teams and the emergency services. Radio channels for tunnel users,

through which it is possible to transmit information and instructions related to safety, numerous sensors destined for taking measurements and detection,

CCTV network. an AID system (Automatic Incident Detection) is usually associated with a CCTV system. The AID

system requires an increased number of cameras in order to make detection more reliable and morerelevant.

1.2.4.2.g Signalling

Signalling refers toSection 8.9.

Even more than for the other facilities, an overabundance of signalling is detrimental to its relevance andobjectives.

The legibility, the consistency, the homogeneity and the hierarchy of signalling (priority to evacuationsignalling and information for users) have to be a priority of the signalling design inside the tunnel and onits approaches.

Fixed signage panels, traffic lanes signals, variable messages signals, traffic lights and stopping lights,signalling to emergency exits, the specific signalling of these exits, signalling of safety niches, physicaldevices for closing the lanes (removable barriers),horizontal markings and horizontal rumble strips are allpart of the signalling devices. They assure a part of the communication with the users.

1.2.4.2.h Devices for fire fighting

The devices for fire detection are either localised (detection of fire in the underground substations or thetechnical rooms), or linear (thermal sensing cable) inside the traffic space.

There are various devices for fire fighting: automatic facilities in the technical rooms and underground substations, powder extinguishers for use by drivers, facilities for firemen: water pipe and hydrants - foam pipe in some countries. The volume of the

water tanks is variable. It depends on the local regulations and the particular conditions of thetunnel.

Some tunnels have an FFSS (see § 1.2.4.2.c above).

1.2.4.2.i Miscellaneous equipment

Other equipment may be installed according to the objectives and needs concerningsafety, comfort andprotection of the structure. Some examples are:

luminous beacons inserted in the side walls or walkway kerbs,

a hand rail or a "life-line" fixed on the side wall permitting the movement in safety of firemen in asmoke-filled atmosphere,

painting of the side walls or the installation of prefabricated panels on the side walls, devices for the protection of the structures against damage resulting from a fire. Such protective

arrangements have to be taken into account from the origin of the project. Thermal exchanges (withthe concrete lining or with the ground) are indeed modified during a fire, as well as aircharacteristics, which must be designed for when dimensioning the ventilation facilities,

management and treatment of water collected on the road pavement inside the tunnel beforedischarge outside in the natural environment,

arrangements for the measurement of environmental conditions at the tunnel portals, associated withparticular operational procedures if the limits defined by the regulations are exceeded.

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1.3. Renovation – upgrading of existing tunnels

The upgrading (in particular for safety improvement) and refurbishment of existing tunnels in operation

gives rise to specific problems of analysis and method. The degree of freedom is less than for new tunnels,because it is necessary to take into account the existing space and constraints. The technologies peculiar toeach type of equipment and their integration are however identical.

The renovation and upgrading of a tunnel under operation quite often result in an increase of theconstruction schedule and costs, in much lower safety conditions during the works, and with badlycontrolled impacts on the traffic volume and conditions. These disadvantages are often the result of anincomplete analysis of the existing situation, the real condition of the tunnel, its facilities and itsenvironment, as well as of a lack of strategy and procedures that would mitigate the effects on the traffic.

Section 2.8proposes a methodology for the safety diagnosis of existing tunnels and the development of anupgrading programme. In addition, Section 4.9 presents specific issues related to works carried out ontunnels in operation. Their dispositions help mitigate the problems mentioned above.

It however appears appropriate to draw the reader's attention to the key points of the following sections.

1.3.1. Diagnosis

Detailed and rigorous diagnosis of a tunnel is an essential stage in the process of its upgrading orrenovation. Unfortunately this stage is often neglected.

The physical diagnosis of a tunnel requires:

to establish in detail and to describe in a precise manner the functions and the geometry of thestructure,

to establish a detailed condition statement of the structure. To evaluate in particular fire resistance,uncertainties and potential risks, and to list the tests that would be needed in order to provide a solidbasis for the detailed design,

to list all existing equipment, their functions, their condition, their technology, their actual features(tests or measurements will be required) and the stock of spare parts that might be available,

to evaluate the remaining life span of the aforementioned equipment before their replacement, andto identify the availability or not of spare parts on the market (notably because of the technologicalobsolescence),

to identify maintenance and inspection reports, equipment malfunctions and the rate of breakdowns.

This physical diagnosis must be supplemented by a diagnosis concerning the organisation, maintenanceand operation procedures, as well as by a specific diagnosis concerning all documents relating to the

organisation of safety and rescue interventions. This stage of diagnosis may eventually lead to the settingup of actions for the training of the various intervention parties in order to improve the global conditionsof safety of the tunnel in its initial state prior to renovation.

The diagnosis must be followed by a risk analysis of the tunnel based on its actual state. This analysis hasa double objective:

to assess if the tunnel can continue to be operated in its present state prior to renovation, or if it isnecessary to take temporary transitional arrangements: restriction of access to some vehicles only -strengthening of the arrangements for surveillance and intervention - additional equipment - etc.,

to constitute a referential of the existing state from the point of view of safety in order to refine thedefinition of the renovation programme.

The diagnosis has to identify (without running the risk of late discoveries during the works period) if the

existing facilities, supposedly in working condition, can be modified, be added to or integrated in the

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future updated facilities (technological compatibility - performance in particular for data collection andtransmission, automatic functioning devices and SCADA).

1.3.2. Renovation or upgrading programme

The renovation or upgrading programme proceeds from two stages.1.3.2.1. First stage: programme development

The development of the programme results from:

the detailed diagnosis as described above,

the risk analysis developed considering the initial state of the tunnel,

the gaps noted concerning safety,

the analysis of what it is possible to achieve in the existing spaces and their potential enlargementsin order to enable the upgrading of the tunnel.

Depending on the physical environment of the tunnel and the spaces available, the optimum upgradingprogramme for the infrastructure or equipment may not be feasible under acceptable conditions, and that

it is necessary to define a more restricted programme. This restricted programme may require theimplementation of mitigating measures ensuring that the required level of safety is achieved in a globalsense, after completion of the works.

1.3.2.2. Second stage: validation of the programme

The validation of the programme requires:

development of a risk analysis based of the final state of the tunnel after upgrading in order to testthe new arrangements introduced by the programme. This analysis has to be established with thesame methodology that the one used for the prior analysis based on the initial state. It also enables asearch for optimisations,

detailed examination of the feasibility of the works to be carried out for the improvement or the

renovation under the requisite conditions of operation: for example, banning of tunnel closure or of temporary traffic restrictions. In case of incompatibility between the objectives of the programmeand the works required for its application, iteration is necessary. This iteration may concern :

- the programme itself, insofar as adaptation of the programme is compatible on the one handwith the safety objectives, and on the other hand with its implementation in the requiredconditions of operation,

- the required conditions of operation that it may necessary to modify in order to be physicallyable to carry out the works resulting from the upgrading programme.

The upgrading or improvement programme does not necessarily require physical works. It may onlyconsist in a modification of the functions of the tunnel, or of the operating arrangements, for example:

modification of the category of the vehicles authorised to access the tunnel: no access to trucks – no

access to vehicles carrying dangerous goods, setting up of specific procedures for traffic restriction: in a permanent way or only during peak

traffic,

tunnel operated initially in bi-directional traffic, transformed for the implementation of unidirectional traffic,

modification of the means for supervision or intervention.

1.3.3. Design implementation and construction

The stage of design implementation and construction involves translating the renovation or upgradingprogramme into technical and contractual specifications and implementing it.

This stage requires a very detailed analysis of:






the successive stages of construction, the content of each of these stages, the logical and prioritysequences of the works,

safety conditions inside the tunnel at each construction stage. This requires partial risk analyses andthe implementation if necessary of mitigation arrangements: traffic regulation – traffic restrictions -patrol – strengthening of the intervention means - etc.

traffic conditions inside the tunnel and on its approaches, with partial and temporary restrictionsaccording to the various stages of works (different arrangements for daytime and night-time, fornormal periods and vacation periods), of the potential diversions, of the global impact on the trafficand safety conditions in the areas concerned by the works,

the constraints and subjections, the partial and global contractual deadlines for the works, in order tobe able on the one hand to define the contractual specifications for the contactor, and on the otherhand to implement all necessary temporary arrangements, and to proceed to an informationcampaign for the users and residents.




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1.4. Stages of the "tunnel life"

Arbitrarily the "tunnel life" may be broken down in several main stages whose essential stakes are:

1.4.1. Design

This is the most important stage of the life of a new tunnel. It is decisive in terms of construction andoperation costs, safety, as well as management of the technical and financial risks.

This stage requires a transverse integration of all interfaces of the “complex system" that constitutes atunnel. This integration has to start from the earliest stage of the design (see paragraphs above).

Experience testifies to the fact that this is unfortunately rarely the case and that often the design of atunnel results from a succession of stages considered as independent. Albeit caricaturising, we can notethat:

the function is not always clearly defined, the alignment is designed without any integration of the tunnel, of its constraints, or of the whole setof optimisation possibilities,

the civil engineering “manages” with the set horizontal and vertical alignments, with all theconsequences that can result concerning the construction costs and risks,

the equipment, safety level and operation fit in somehow and not always harmoniously or optimallywith the arrangements chosen during the previous stages.

1.4.2. Construction

For what concerns Civil engineering, the most important aspect is the management of technical risks (inparticular geological) and of all the resulting consequences concerning construction costs and duration.

Considerations relating to risk management for the construction have to be taken into account from thedesign. These considerations must be detailed and shared with the owner of the tunnel. Decisionsconcerning the risks must be developed and clearly documented.

The decision to take some risks does not necessarily constitute a mistake and must not necessarily beforbidden, because as a result some imperatives may be met, for example concerning a tight schedule,which would be incompatible with the implementation of all the investigations that would be required toeliminate all uncertainties.

However the decision to take a risk must result from a very detailed reflection concerning:

consequences that may result, which must be clearly identified, analysed and consigned: delays -costs - human and environmental impacts – safety – schedule – etc.,

the real issues of this decision, its probability of success and its real interest.

Taking of a risk must not be the result of carelessness or incompetence on the behalf of the various parties.

For what concerns Operational facilities, the reader’s attention is drawn to:

all aspects likely to optimise the life span of the equipment, its reliability and ease of maintenance, the need of rigorous process and continuous control of the functionality, performances and quality

of the equipment throughout the manufacture of the components, their assembly, their installationon the site, then at the time of partial and global testing after integration,

the added bonus to quality concerning the choice of the equipment and the contractor, even thoughthe construction costs may be a somewhat higher. Possible savings due to reduced initial costs areoften quickly compensated for by higher maintenance costs, difficulties of intervention under traffic,

and the additional constraints that would be suffered by the users.




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1.4.3. Commissioning

This stage of "tunnel life" is often under-estimated and taken into account tardily. It requires taking timethat is not often granted, and leads to the commissioning of the tunnel under unsatisfactory conditions, oreven under conditions that are highly exposed in terms of safety.

This stage includes: the organisation of the operation and maintenance, development and adjusting of all procedures of operation, maintenance, intervention and safety

under the normal conditions of tunnel operation, as well as under MOC (Minimal OperationConditions),

recruitment and training of the staff, the “dry run" of all the facilities, that cannot take place before the equipment has been fully

completed, tested and delivered (possibly with provisions requiring only minor correctiveinterventions),

the practice, training and manoeuvres involving all the intervention teams and services beforecommissioning the tunnel.

1.4.4. Operation

The main mission is to ensure:

the management of all facilities, their maintenance, their restoration, the safety and the comfort of the users.

It is also necessary to be able to look at the situation objectively with a distance to the daily routines inorder to:

establish feedback from experience, adapt the procedures, the conditions of intervention, thetraining and the manoeuvres for safety,

optimise operation costs without damaging the level of service and safety, identify, analyse, plan and achieve heavy repairs, and renovation and upgrading works.




http://tunnels.piarc.org/en/strategic-issues/costs.htm 30 / 35

1.5. Costs of construction, operation, upgrading - financial aspects

1.5.1. Foreword

Tunnels are relatively expensive civil engineering structures with respect to their construction andoperation. Particular attention must be paid from the beginning of the project in order to spot any possibletechnical and financial optimisations.

It is recommended from the first stages of the design to implement a process including:

the detailed definition of the "function" of the tunnel, an iterative process of “value engineering analysis" achieved at all strategic stages of the project, to

which must be integrated into the various stages of the risk analysis, detailed analysis and monitoring of the potential risks in the design and construction stages. These

potential risks are related to:- technical uncertainties relating in particular to the complexity of the ground (geological and

geotechnical uncertainties),-

uncertainties of traffic volume forecasts, that constitute an important risk concerning earnings inthe case of construction and financing by “concession",- uncertainties and risks concerning the financial environment, in particular changes in interest

rates and conditions of financing and refinancing. This aspect constitutes an important risk inthe case of construction and financing by "concession" or by PPP (Private Public Partnership)with a financial contribution.

This process will enable the optimisation of the project (construction and operation costs) and animproved management of the technical and financial risks, as well as the schedule.

1.5.2. Construction costs

1.5.2.1. Cost ratios per kilometre The construction costs of tunnels are very variable and it is impossible to give representative ratios of costs per kilometre, because these ratios may vary in important proportions (average of 1 to 5) accordingin particular to:

the geological conditions, difficulties concerning the access roads and the tunnel portals, the geographical location of the tunnel: urban or non-urban, the length of the tunnel: in particular the "weight of the ventilation facilities and safety

arrangements is more significant for a long tunnel; on the other hand all the works concerning theaccess roads and portals have a more important impact for a short tunnel,

the traffic volume which is a determining factor for the dimensioning of the number of lanes, as

well as for the ventilation facilities, the nature of the traffic: in particular a tunnel used by vehicles carrying dangerous goods will

require expensive arrangements for ventilation, safety and possibly the resistance of the structure tofire; conversely, a tunnel dedicated to the passage of only light vehicles may enable very importantsavings because of the possible reduction of the width of the lanes, headroom and reducedrequirements for the ventilation facilities,

the tunnel environment that may lead to expensive protection arrangements for the mitigation of itsimpact,

arrangements taken for the management or the sharing of construction risks, the socioeconomic environment of the country in which the tunnel is to be constructed. The impact

can reach about 20% of the costs.At most it is possible to indicate that the average cost of a usual tunnel, built under average geotechnical

conditions is about ten times the cost of the equivalent infrastructure built in open air (outside of urbanareas).





1.5.2.2. Breakdown of the construction costs

The construction cost of a tunnel may be broken down into three types of cost:

the cost of the civil engineering structures, the cost of the operation facilities, including the supervision centre and the energy supply from

public networks, various costs including in particular: owner’s costs for the development of the project – project

management – design and site supervision – survey and ground investigations - environmentalstudies and mitigation measures – land acquisitions - various procedures - etc.

The two diagrams below show examples of the breakdown of construction costs, on the one hand fortunnels for which the conditions of the civil engineering works are not complex, and on the other hand fortunnels for which the conditions of the civil engineering works are less favourable.

Fig. 1.5.1: Breakdown of construction costs

Note: these two diagrams show how important the costs are of the civil works and illustrate theconsequences of an almost doubling the costs of civil works (right-hand diagram).

1.5.3. Operation costs

The operation costs of a tunnel may be broken down into three types of cost:

the operation costs as such, which essentially include staffing, energy, as well as the managementand expendable equipment. These are recurrent costs;

the recurrent yearly costs of maintenance; the costs of heavy repairs, as well as the replacement costs of the equipment according to its life

span and its state during the tunnel life. These costs are not recurrent and depend on the equipment,its quality and the conditions of maintenance, from the tenth or twelfth year after the start of theoperation period.

The two diagrams below represent examples of breakdown (with constant economic conditions) of theconstruction costs (civil works, operation facilities, various costs) and of the global operation costs(accumulated over a duration of thirty years after the start of the operation period).

Note: these diagrams show how important the operation and maintenance costs are and how it isnecessary to choose from the first stages of the tunnel design the arrangements that enable theoptimisation of the recurrent operation and maintenance costs.

n o p a r t ic u l a r c o m p l e x it y fo r c i vi l e n g i n e e r in g

70 %

15 %

1 5 %

civil

engineering

operation

facilities

various

breakdown of the construction costs

d i f fi c u l t c o n d i t io n s f o r c i vi l e n g i n e e r in g

8 4 %

7 %

9 %

civil

engineering

operation

facilities

various

breakdown of the construction costs





Fig. 1.5.2: Breakdown of the costs during a 30-year period

1.5.4. Costs of renovation and upgrading

This chapter concerns the renovation or upgrading works that are required for “upgrading” to newregulations. The works concern the arrangements for evacuation, the resistance of the structure to fire, theoperation and safety facilities, and all the requirements to satisfy the new safety regulations.

It is not possible to give statistical prices due to the diversity of existing tunnels, their condition, theirtraffic and the more or less important requirements of new safety regulations that may vary from onecountry to another.

The observations made in France for this nature of upgrading works for complying with the newregulations, which have been carried out since the year 2000, show a large variation of the correspondingbudgets with a range of costs between about ten million Euros and several hundred million Euros (therehave been several upgrading programmes with a budget of more than 200 million Euros).

1.5.5. Aspects relating to financing

Tunnels constitute costly infrastructure in terms of construction and operation, but this is offset byeconomic benefits including regional development, traffic fluidity, comfort, safety, reliable routes(mountain crossings) as well as protection of the environment.

Financing of these works is ensured either by:

the “traditional mode”: financing and maintenance by a public authority, the financial resourcescoming then from public taxation or fuel taxes,

a "concession" to a private or semi-public body, which is charged with the construction and theoperation of the tunnel during a contractual period of time. This body is in charge of the financing(often partly by loan), which is offset by a toll paid by the users, that reimburses the costs of theconstruction and the operation, as well as the risks and the financial expenses. This type of "concession" can be granted by the financial involvement of the grantor or by particular guarantees(example: guarantee of a minimal traffic volume with the payment of a financial compensation if this minimal traffic volume is not reached),

“mixed mode” of PPP (Public Private Partnership) or similar, that may concern:- only the construction or the construction and the operation,- construction under a “turnkey” scheme in the case of a “design and build” process,- partial or whole financing.

The present manual does not intend detailing these various modes of financing, or presenting theirmechanisms, their advantages or disadvantages. However it is interesting to present some main guidelinesfound from experience, which give a preliminary illustration.

d i f f i c u l t c o n d i t i o n s f o r c i v i l e n g i n e e r i n g

80 , 0%

5, 5%

6, 0%

8, 5%

construction

operation

maintenance

hea vy repa irs

n o p a r t i c u l a r c o m p l e x i t y f o r c i v i l

e n g i n e e r i n g

71%

8 %

9 %

12 %

construction

operation

maintenance

heavy repa irs





a) Financing by a public authority

This mode of financing is employed widely. It allows the development of an infrastructure project,whose financing could not be achieved by a “concession” (by lack of sufficient income from tollcollection), or when there is political will to avoid a toll.

It requires however that the public authority has the financial capacity to ensure this financing, orthat it has the capacity to borrow money and to support a debt. The financial resources essentiallycome from public taxation or fuel taxes and sometimes partially from toll collection.

b) Financing by “concession” – tunnel part of a global infrastructure

The financing of a “non-freestanding tunnel” by a “concession” (with or without financial involvement of the grantor) is the general case for a tunnel that is part of a new interurban highway with toll collection.

The costs (construction and operation) of the tunnel are shared out among the tunnel and the linearinfrastructure above ground. Experience shows that the over-cost of the average toll ratio per kilometre isaccepted by the users as long as the new infrastructure brings sufficient added value concerning timesavings, better or more reliable service, comfort and safety.

c) Financing by "concession" - isolated tunnel

Two main categories of isolated tunnels exist.

Tunnels corresponding to a major improvement of the traffic conditions. This is in particular thecase of urban tunnels aiming to alleviate traffic and to reduce travel times. Experience shows thatfinancing by “concession” is only really foreseeable when the following conditions are met:

- high traffic volumes,- country with high standard of living and revenues, enabling substantial toll rates, which are

essential to ensure the financial balance,- Significant time gains for the users so that they will accept in return a relatively high toll rate,- duration of the concession of about fifty years at least.

“Regional development” tunnels, intended to cross a major natural obstacle (chain of mountains -estuary). These obstacles constitute an important handicap for trade. The initial traffic volume is

usually relatively low. The new link with the tunnel will enable the growth of traffic, but such adevelopment is often very difficult to predict in advance, and it constitutes an essential parameter of financial risk for the funding of the concession. Experience shows that financing by "concession" isthen only realistic when the following conditions are met:

- The natural obstacle is significant and the tunnel is sufficiently attractive (gain of time, level of service, delivered service, reliability of the link) in order to attract all existing traffic in spite of the toll,

- Financial involvement of the grantor (possibly also the stakeholders), either with a financialcontribution or direct involvement in the construction and the financing of a part of the works(for example construction of the access roads),

- Guarantee of a minimal traffic volume by the grantor, with the payment of a contractualfinancial contribution if the minimal traffic volume is not reached,

-Contractual arrangements for sharing major risks can put the financial model at risk if theyover-run limits or conditions defined by the contract,

- Very long concession duration: often 70 years or more,- Financial guarantee brought by the grantor, in order to enable the concession body to benefit

from more favourable conditions of loans on the financial market, which may better ensure thefeasibility of the financial plan.

d) Financing by PPP or similar

The range of contents of a PPP mode is very wide, and it is difficult to establish guidelines becauseof the scope of possibilities.

This mode of financing commits public authorities to financial contribution in the long term.Detailed analysis is necessary to evaluate the real advantage of this mode of financing compared to

traditional financing. Indeed, this mode of financing very often contributes to increasing the global





cost of the project (with equal functionality and quality) because of the compensation of the riskassumed by the developer.

Public authorities have to carefully define the required functions of the tunnel, as well as objectivesconcerning quality, comfort, safety, level of service, life span, rate of availability, penalties etc. inorder to prevent any ambiguity that may result in important misunderstandings and financial

overruns in the development of the project.




1.6. Regulations - Recommendations

Countries that have many tunnels are endowed with regulations and have developed recommendationsand guidelines for the design, construction, operation, maintenance, safety and the intervention of therescue services.

Concerning safety conditions in road tunnels, countries belonging to the European Union are subjected toDirective 2004/54/CE that prescribes a minimum level of arrangements to be implemented in order toensure the safety of users in tunnels longer than 500 m that are part of the trans-European road network. Awider group of European countries are also bound by an international convention, The EuropeanAgreement concerning the International Carriage of Dangerous Goods by Road (ADR) and includesspecific arrangements for tunnels. Every member country has transposed these European regulations to itsown national legislation. Some member countries have implemented additional regulations that are moredemanding than the one that results from the transposition of the European regulation.

A list of the regulations and recommendations concerning the operation and the safety of road tunnels hasbeen established in cooperation between the PIARC and the ITA Committee on Operational Safety of Underground Facilities (ITA-COSUF) of the international tunnelling and underground space association(ITA - AITES). This document can be consulted on theITA-COSUF web site. This list is not exhaustivebut presents an international panel of twenty-seven countries and three international organisations.

Many countries do not have any regulations relating to tunnels and to tunnel safety, because they do nothave road tunnels within their territory. It is recommended that these countries choose a complete andcoherent package of the existing regulations of a country with lengthy experience in the field of tunnels,and not to multiply the origins of the documents by dipping into different sources. The recommendationsof PIARC, as summarised in the present manual, as well as those of European directive 2004/54/CE alsoconstitute international references that are being applied increasingly often.

http://tunnels.piarc.org/csite/link/dl?site=tunnels.en&objectId=25

http://live.unece.org/trans/danger/publi/adr/adr_e.html

http://cosuf.ita-aites.org/

http://www.ita-aites.org/





http://www.ita-aites.org/


http://live.unece.org/trans/danger/publi/adr/adr_e.html


Documents

1. Strategic Issues