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Assessing the Condition of the Irish Regional Road Network 2011/2012

Engineers Ireland, Nov. 2012 Page 1

Assessing the Condition of the Irish Regional RoadNetwork 2011/2012

AUTHORS:

Dr. Kieran Feighan, BE, MSCE, Ph.D, CEng, MIEI,Managing Director, PMS Pavement Management Services Ltd.Brian Mulry, BE, MEngSc, CEng, MIEI, MIAT,Director, PMS Pavement Management Services Ltd.

ABSTRACT

A major pavement condition study of the Regional road network was carried out for the Department ofTransport, Tourism and Sport (DTTAS) and the National Roads Authority (NRA) in 2011/2012. Themain objectives of the study were to establish the existing pavement condition, and the length andarea of regional roads requiring remedial works, both nationally and at county level.

The entire Regional road network, comprising 673 Regional roads and 13,055 kilometres of road, wassurveyed in one direction as part of the 2011/2012 study. The pavement condition study involved theuse of machine surveys to collect road condition data, skidding resistance data and digital imagery onthe Regional road network. The road condition data was collected using the Road Surface Profiler(RSP) machine and the skidding resistance data was collected using the Sideways-force CoefficientRoutine Investigation Machine (SCRIM). The outturn parameters were visual rating (VR), internationalroughness index (IRI), rut depth, mean profile depth (MPD) and SCRIM coefficient (SC). Thecondition parameters were reported for each 100 metre length of the entire regional road network.The visual rating was carried out from high definition video used to capture the road surface conditionand using a newly developed 1 to 10 rating system for Irish roads.

The study also compared the results of the 2011 survey with a similar study on c. 8,000 km of theNon-National road surveyed in 2004. The results of the study show that there has been a substantialimprovement in ride quality (IRI) on the Regional road network over the seven year period. Nationally,the percentage length of the Regional road network in the Road Reconstruction category has droppedvery significantly from 24% in 2004 to 15% in 2011. The results of the 2011 study provide a basis forallocation of funding on a needs basis, and will have significant implications for local authority roadsfunding in the future.

1. INTRODUCTION

The roads network in Ireland is by far the most used transport infrastructure for the movement ofgoods and people and is of critical economic and social importance due to the dispersed nature of thepopulation and industrial development. According to the National Development Plan (NDP) 2007 -2013, 98% of all goods are transported on the road network in Ireland (1). The Non-National roadscomprising Regional and Local roads account for 94% of the road network and carry around 54% ofall road traffic (2).

The Regional road network makes up 13,055 kilometres of road, comprising 673 routes, whichaccount for about 15% of the non-national network and carries about 30% of all road traffic. Theregional roads play a vital role in the development of key economic sectors such as industry, tourismand agriculture. In addition, the regional roads provide mobility within and between local economies



and are an important link to the national road network and to Ireland’s ports and airports whichprovide access to the wider European economy (3).

The Department of Transport, Tourism and Sport (DTTAS) and the National Roads Authority (NRA)commissioned PMS Pavement Management Services Ltd. (PMS) in 2011 to carry out a pavementcondition study on the Regional road network (4). The pavement condition study comprised the use ofmachine surveys to collect road condition data, skidding resistance data and digital imagery on theentire Regional roads network. The main objective of the Regional Road Pavement Condition Studywas to establish, by county and nationally, the lengths and areas of regional roads that require varioustypes of remedial works.

The 2011/2012 study consisted of the following data collection elements and project deliverables:

1. Road Condition Data (RCD) and Skidding resistance data on the entire regional road network;

2. Provision of very accurate 3D GPS traces of the network;

3. Provision of high quality digital video and visual rating of the network, and

4. Development of a methodology to determine remedial work quantities from the visual ratingand machine data collected.

Another objective was that comprehensive information on the current status of regional roads shouldbe obtained to quantify the current status of road conditions within counties and nationally, and toprovide a benchmark measurement against which the future actual road conditions can be compared.

It is anticipated that the results of the study will form an important part in the ongoing process ofsecuring and allocating resources to the non-national road network and in the implementation of themulti-annual restoration programmes. To this end, information on actual road conditions, as well ason lengths and areas of various types of remedial works, needed to be gathered to facilitatecomparisons over time.

Finally, it was a requirement that all survey data collected should be compatible with the LocalGovernment Computer Services Board (LGCSB) MapRoad package as this is already installed in alllocal authorities and provides the most appropriate and most efficient means of distribution of thecollected data at local authority level.

2. ROAD CONDITION DATA

Two previous major national studies of the non-national roads were carried out in 1996 and 2004. Inthe 1996 DOE Pavement Condition Study, the survey methodology was based around the manualPavement Condition Index (PCI) windshield visual condition survey, where the pavement conditionwas identified from a slowly moving vehicle for each 100 metres (5) (6). In the 2004 DEHLG PavementCondition Study, the survey was based around a modified version of the windshield method wherepavement condition was identified from high definition video, Video Pavement Condition Index (VPCI),and an additional ride quality parameter, the international roughness index (IRI) was reported for each100 metre interval (7) (8). The 1996 and 2004 surveys were based on a sampling of the non-nationalroads network with almost 8000 kilometres of roadway being surveyed in the 2004 survey.

The 2011/2012 Regional Road Pavement Condition Study was based principally around machine-based data. The road condition data was collected using the Road Surface Profiler (RSP) machineand the skidding resistance data was collected using the Sideways-force Coefficient RoutineInvestigation Machine (SCRIM). The outturn condition parameters comprised a number of key



pavement performance indicators. The key indicators were visual rating (VR), international roughnessindex (IRI), rut depth, mean profile depth (MPD) and SCRIM coefficient (SC). The visual rating wascarried out from high definition video used to capture the road surface condition and using a newlydeveloped 1 to 10 rating system for Irish roads. The condition parameters were reported for each 100metre length of the entire regional road network.

3. ROAD CONDITION DATA COLLECTION EQUIPMENT

The study was completed by PMS using two RSP and two SCRIM machines. The RCD, SCRIM andvideo data were both chainage- and geo-referenced. Each survey vehicle was equipped with a veryaccurate DMI (Distance Measuring Instrument). The DMI’s were calibrated and maintained throughoutthe contract so that all measured data was referenced to a longitudinal position on the road to anaccuracy of 0.1% or better from the start location of that survey. A high-specification GPS (globalpositioning system) device and INS (Inertial Navigation System) was also attached to the surveyvehicles and connected to the hardware interface.

3.1. ROAD SURFACE PROFILER (RSP)

The RSP machine is a Dynatest Model 5051 Mark III RSP test system. The RSP is a multi-purposedata collection system equipped with a computer, state-of-the-art lasers, accelerometers and inertialmotion sensors for recording pavement performance data using a number of onboard sub-systems.The RSP is capable of real-time continuous high-speed measurements of:

Sub-System 1: Longitudinal Profile (including International Roughness Index (IRI)) Sub-System 2: Transverse Profile (Rut Depth) Sub-System 3: Macrotexture (Mean Profile Depth) Sub-System 4: Geometrics (Crossfall, Gradient and Radius of Curvature) Sub-System 5: Forward View/Pavement Oriented Digital Video Sub-System 6: DMI linear chainage coordinate system Sub-System 7: GPS geo-referencing coordinate system

The RSP Mark III meets the requirements of specified national and international standards (9) (10) (11) (12)

(13). The RSP can collect data at speeds up to 115km/hr, but is typically operated at normal trafficspeeds of c. 70 km/hr ensuring that there is no delay or disruption for other road users.

Figure 1 shows the RSP machine used inthe study. The laser sensors,accelerometers and inertial motion sensorare mounted in a Transducer Unit or “RutBar” at the front of the vehicle. The basicrut bar is 1.83m in length. Using a numberof additional angled wing lasers on bothends of the basic rut bar, the total effectivemeasurement width is increased to 3.2m.

Figure 1: The RSP Multi-function SurveyVehicle



3.2. SIDEWAYS-FORCE COEFFICIENT ROUTINE INVESTIGATION MACHINE (SCRIM)

The skidding resistance of the regional road network was measured using SCRIM. The SCRIM hasbeen used in Ireland since 1985 to measure the skid resistance on National Primary and NationalSecondary networks. The output from the machine is used to identify stretches with unacceptably lowwet skidding resistance, and is a key parameter used by the NRA and the local authorities inprioritising road sections for treatment.

The skidding resistance survey was completed using two SCRIM machines. One SCRIM machinewas mounted on a Volvo truck chassis and has a very large capacity tank of 6,200 litres. The secondSCRIM is a smaller machine mounted on an Iveco truck chassis with a tank capacity of 3,500 litres.The SCRIM machines used in the study met the requirements of specified national and internationalstandard conditions (14) (15) (16) (17) (18).

Figure 2 shows the larger SCRIMmachine used in the survey. TheSCRIM machine operates by applyinga freely rotating wheel, at an angle of20o to the direction of travel, on to thewetted road surface under a knownload. The machine has a waterapplication system (tanks, pumps, etc)mounted on a rigid truck body which isdesigned to apply a constant controlledwater film thickness on to the roadsurface in front of the test wheel.

Figure 2: SCRIM Machine

The vertical load and the sideway force generated by the frictional resistance to skidding of the testwheel are continuously measured. The ratio of the sideway-force to the vertical load on the wheel isthe sideway-force coefficient (SFC), which is expressed as a decimal.

The SCRIM survey on the regional roads was carried out at the target test speed of 50km/hr, and theskid resistance was continuously measured in the left hand wheelpath with the average SFC for each10 metre length being recorded. The SCRIM coefficient (SC) value is derived from the recorded SFCdata.

3.3. DIGITAL VIDEO SYSTEM

The RSP and SCRIM vehicles were equipped with a high-resolution digital video (DV) camera systemmounted in the cab of the survey vehicle and used to record a forward view surface-orientated videoof the road pavement. The digital camera was capable of capturing images at user-selected intervalsas low as 3 metres.

The video frames and associated route information were compressed and written to a high-speedhard disk. All of the data capture was in real time.



Figure 3 shows the Video camera system used inthe study. The digital video was subsequentlypost-processed in the office to carry out a visualrating of the road surface condition.

In addition, the video provides a permanentrecord of the road surface at the time of testing,and can also be used for other pavementmanagement purposes such as visualassessment of pavement defects, singage, linemarkings etc.

Figure 3: Forward View Video Camera

3.4. GPS REFERENCING EQUIPMENT

The RCD, SCRIM and video data were geo-referenced using high specification GPS (globalpositioning system) and INS (inertial measurement system) technology. This ensured maximumcompatibility with the LGCSB MapRoad system (where the underlying data storage is chainage-based) as well as full compatibility with other GIS systems including MapInfo or ArcGIS (NRAcompatibility). The GPS equipment was integrated with an INS so that National grid co-ordinatescould be derived from the GPS data irrespective of the quality of the satellite coverage. The 3-dimensional spatial co-ordinates of the position of the equipment during the survey were measured atpoints separated by no more than 5.0 m of distance travelled.

4. QUALITY OF SCRIM AND RCD DATA

There was a particular challenge in the quality assurance of this project, as PMS were using two RSPmachines and two SCRIM machines to carry out data collection simultaneously. It was very importantthat all of the machines were regularly checked and cross-correlated on control test circuits to ensurethat all of the data collected nationwide was to the highest quality in relation to consistency andaccuracy.

For the duration of the project, all machines were monitored with daily checks and calibrations prior totesting, and weekly surveys on long-established test circuits in Galway with differing SC, IRI, rut depthand MPD values for road condition surveys. The same control circuits as had been used for the NRAannual survey of the National network since 2005 were used for the 2011/2012 survey of the Regionalroad network. The control sites were surveyed twice weekly during the survey programme, typically atthe beginning and end of each survey week. The control site data was checked to ensure that themachines were measuring all parameters accurately, and that the DMI and GPS were performingwithin specifications. In addition, the test circuit data from the two SCRIM and two RSP machineswere cross-correlated to ensure that the machines were measuring consistently. This approachmaximised the consistency of data collected country-wide throughout the project.

5. PAVEMENT CONDITION EVALUATION FROM VIDEO

A visual inspection of the pavement condition, identifying pavement distress types and severities is aninvaluable aid in the evaluation of a pavement's performance. However, there are situations where it



is uneconomical to perform a detailed manual distress survey on pavement sections. This isparticularly the case on lower class roads, where the available budget per kilometre is at a low level,and the costs of data collection per kilometre become excessively high as a percentage of theavailable budget. A system whereby greater lengths of road can be surveyed in a given time period isobviously attractive for these road classes.

In the 2011/12 Regional Road Study, the high definition digital video was used to carry out a VisualRating of the road surface condition. Once the digital video data is collected in the field, the visualrating survey can be carried out indoors, and is completely independent of weather conditions. Use ofvideo for condition evaluation has some clear advantages over a manual inspection:

The video can be played at different speeds, paused, reversed etc. when the inspector wants tobe sure that the distress identification is correct

The inspector can concentrate completely on distress identification Multiple inspectors can be used in the post-processing phase to expedite the duration of

processing Inspection and identification is carried out in safe and comfortable surroundings Auditing of the distress identification and 1 to 10 rating process is very straightforward and much

less costly than field auditing A permanent record of the road condition is saved and can be subsequently re-processed if

required for other uses, e.g. Presence/absence of road markings, road signs, number of junctions,edge drainage etc.

DTTAS, NRA or local authority personnel can view the video at any subsequent time for anyrequired purpose

The video files can be subsequently attached to the road segments in MapRoad and can beviewed from within MapRoad in conjunction with the road condition data derived from the videoand ride quality measurement devices.

6. CONDITION PARAMETERS

The outturn condition parameters from the 2011/2012 Regional Road Study were visual rating (VR),international roughness index (IRI), rut depth, mean profile depth (MPD) and SCRIM coefficient (SC).The condition parameters were reported for each 100 metre length, referred to as a 100 metre sampleunit, of the entire regional road network.

6.1. VISUAL CONDITION

The Visual Rating (VR) was carried out using a simplified 1 to 10 rating scale developed specificallyfor Irish Non-National road conditions. The rating system was developed by PMS in collaboration withthe DTTAS and Senior Engineers in South Tipperary County Council and Carlow County Council. Thevisual rating is based on the PASER (Pavement Surface Evaluation and Rating) methodologyoriginally developed by the Wisconsin Department of Transportation for local roads in the US (19).

The PASER system was significantly modified for Irish conditions and remedial work types to producethe DTTAS Flexible Roads Manual - Pavement Surface Evaluation and Rating on Irish Roads(20). The condition rating system provides a numerical rating on a scale of 1 (totally failed) to 10(excellent) based on a visual rating of the pavement surface. Table 1 shows the 1 to 10 rating system.



The rating manual provides details of distress descriptions, how to link them to the 1 to 10 visualrating scale, with colour photographs of distress type and examples of road pavements in each of the1 to 10 rating categories. There are four main categories of common flexible road surface defects onIrish roads outlined in the manual as follows:

Surface DefectsRavellingBleeding

Pavement DeformationRuttingSurface Distortion

CracksAlligator CrackingEdge Cracking/BreakupOther Cracking (longitudinal, transverse, reflection, slippage, etc.)

Surface OpeningsPatchingPotholesRoad Disintegration

With an understanding of these surface defects, one can evaluate and rate pavement surfacecondition. The 1 to 10 Visual Rating (VR) is directly linked to the four remedial works categories of:Road Reconstruction; Surface Restoration; Restoration of Skid Resistance, and RoutineMaintenance. Table 2 shows the mapping of the 1 to 10 rating to the different treatment measures.

The visual rating (VR) of the regional roads was carried out using the 1 to 10 rating system from theforward view digital video recorded in the field. Typically c. 200 kilometres of road per day could berated and recorded using specially developed computer software. For consistency with the othercondition parameters reported, a Visual Rating value was assigned to each 100 metre length of theentire regional road network.

6.2. INTERNATIONAL ROUGHNESS INDEX (IRI)

The road user’s view of satisfactory or unsatisfactory road condition is primarily influenced byroughness or ride quality. Longitudinal profile is the main factor controlling road roughness and hencethe user perception of road condition. The International Roughness Index (IRI) is a scale forroughness based on the response of a standardised motor vehicle to the road surface and iscalculated from longitudinal profile measurements. The IRI is expressed in units of millimetres permetre (mm/m), with low values indicating smooth roads, and high values indicating rough roads withpoor ride quality.

In the 2011/12 Regional Road Survey, the RSP laser profilometer system was used to measure theraw longitudinal profile and to calculate the IRI value in both the left and right wheelpaths for each 10metre interval surveyed. The average of the two wheelpath IRI readings, aggregated over 100 metrelengths, was calculated and reported over the full network, as this is considered a better measure ofroad surface roughness than the IRI for either individual wheel track.



OverallRating

Primary RatingIndicators*

Secondary RatingIndicators*

10No visible defects.

Road surface in perfect condition,like new.

9Less than 10 % of surface with Surface Defects1

Road surface in very good condition.

810% to 30% of surface with Surface Defects1

Little or No Other defects.

7Greater than 30% of surface with Surface Defects1

Little or No Other defects.

Old surface with aged appearance.

6Less than 20% of Other Cracking2 may be present.Patching generally in good condition.May be out of shape requiring some reduction in driverspeed.

Surface defects1 may be present.No structural distresses3

5Greater than 20% Other Cracking2 present.Patching generally in fair condition.Out of shape requiring reduction in driver speed.Very localised structural distress3 (< 5 sq.m of surface) maybe present.

Surface defects1 may be present.

4Structural distress3 present.Rutting or Alligator Cracking for 5% to 25% of surface.Short lengths of Edge Breakup/Cracking.Small number of Potholes.

Other defects may be present.

3Significant areas of Structural distress3.Rutting or Alligator Cracking for 25% to 50% of surface.Significant continuous lengths with Edge Breakup/Cracking.Frequent Potholes.

Other defects may be present.

2Large areas of Structural distress3.Rutting or Alligator Cracking for over 50% of surface.Severe Rutting (over 75 mm deep).Extensive Patching in very poor condition.Many Potholes.

Very difficult to drive on.

1Severe Structural distress3 with extensive loss of pavementsurface.Road Disintegration of surface.Many large and deep Potholes.Patching in failed condition.

Severe DeteriorationVirtually undriveable.

*Individual pavements will not have all the types of distress listed for any particular rating.They may have only one or two types.

Note 1: Surface Defects = ravelling or bleeding.Note 2: Other Cracking = longitudinal, transverse, reflection or slippage cracking.Note 3: Structural Distress = rutting, alligator cracking, edge breakup/cracking or potholes.

Table 1: The 1 to 10 Rating System



Table 2: Mapping Rating to Treatment Measures

OverallRating

Treatment Measures

Surf

ace

Stru

ctur

e

10 RoutineMaintenance

Exce

llent

9 Very

Goo

d

8 Resealing &Restoration of Skid Resistance

Fair

Goo

d

7 Poor

6 SurfaceRestoration

–Carry out localised repairs

and treat with surface treatment or thin overlay.Fa

ir

Fair

5 Poor

4 StructuralOverlay

-Required to strengthen road.

Localised patching and repairs required prior to overlay.

Poor

Ove

rall

3

2 Road Reconstruction-

Needs full depth reconstruction with extensive base repair.

Very

Poor

Ove

rall

1 Faile

dO

vera

ll



6.3. RUT DEPTH

Rutting in the wheelpath is a structural distress induced by heavy vehicle traffic. Rutting is manifestedas a permanent longitudinal deformation of the pavement creating channels in the wheelpaths. It iscaused by the consolidation or lateral movement of material under repeated traffic loading,inadequate compaction of the pavement layers during construction or inadequate thickness ofpavement layers.

Transverse profile measurements were recorded by the RSP machines for the regional road survey ata maximum longitudinal spacing of 1 metre in both the left and right wheelpaths. The rut depth inmillimeters (mm) was calculated in both wheelpaths. Rutting in the left wheelpath is generally moresevere than in the right wheelpath, and is typically reported internationally. Average left rut values inmillimetres (mm) were obtained for each 100 metre length from the measured transverse profile forthe entire regional road network.

6.4. SURFACE TEXTURE

The macrotexture or surface texture of the pavement surface refers to the coarser texture defined bythe shape of the individual coarse aggregate particles used in the surface course mix, and by thespaces between the individual aggregate chips. Macrotexture is the major influencing factor onfrictional resistance at higher speeds (>50km/hr) and is particularly important in relation to wetconditions. The macrotexture provides the drainage channels for rainwater to escape to allow thevehicle tyre maintain greater contact with the pavement surface, in particular at high speeds.

The macrotexture profile of the regional road network was measured continuously in the leftwheelpath by the RSP using a non-contact laser system. The macrotexture profile was measured toenable the Mean Profile Depth (MPD) in millimetres to be calculated at 1 metre intervals inaccordance with ISO 13473-1:2004 (13). The average MPD values were reported for each 100 metrelength of regional road.

6.5. SKIDDING RESISTANCE

The skidding resistance of a road pavement is a measure of the frictional resistance generatedbetween the road surface and a tyre under wet conditions. The microtexture of the road surfaceaggregate is the dominant factor in determining wet skidding resistance at lower speeds (<60km/h).Microtexture is primarily a property of the individual pieces of aggregate making up the road surface.The microtexture of the aggregate controls the contact between the tyre rubber and the pavementsurface. From a skidding resistance viewpoint, the microtexture characteristics are measured toassess the degree of polishing and the ability of the aggregate to retain relatively rough microtextureunder the abrasive action of tyre forces. Ultimately, it is the provision of adequate microtexture andmacrotexture that is required for adequate surface frictional resistance over the full spectrum ofvehicle speeds.

The skidding resistance of the regional road network was measured in the left hand wheel path usingSCRIM with the average SFC for each 10 metre interval being recorded. The SFC values areadjusted to represent standardised conditions by applying speed and seasonal correction factors(where applicable) to the data recorded. The SCRIM coefficient (SC) value was derived from thecorrected SFC data using the standard relationships in NRA HD28/11 (18). The SC values werereported based on average values for each 100 metre length over the entire regional network.



6.6. POST-PROCESSING OF DATA AND LOADING OF DATABASE

For the purposes of reporting, the 10 metre data collected in the field was averaged over each 100metre sample unit, which were separately referenced by local authority and road number. The startand end chainage, and the start and end georeferences in Irish National Grid (ING) co-ordinates werealso stored to allow multiple sorting and querying in SQL and GIS databases. All of the post-processed condition data (VR, IRI, Rut, MPD and SC) were loaded into a Microsoft Access database.

There was a total of over 130,000 sample units with VR, IRI, SC, MPD and Rut depth data in the finaldatabase. Customised queries of the data tables were then defined within Microsoft Access to formthe basis for the analysis and reporting of data. In addition, the data on an individual local authoritycould be exported in Access or Excel format and the structure of the final database was fullycompatible with the requirements of the LGCSB MapRoad software package.

7. ROAD SCHEDULE AND PROJECT DELIVERY

A full road schedule, listing all of the road sections in each local authority using a standardised roadnumbering system, was supplied by each local authority. For each road section, information wastypically provided on the road number, road name, engineering area, descriptions of the start and endof the section, and the length and average width of the road. Table 3 shows the total length ofregional road surveyed in each local authority.

At the initiation of the project, PMS devoted considerable resources to compiling a unified GISdatabase showing all of the Regional roads with associated characteristics. Without a unifieddatabase, it was not possible to proceed with developing an effective routing plan for data collection.Upon completion of the unified GIS database, a zoning and routing plan was developed nationally toallow the road condition and skidding resistance data to be collected as efficiently as possible withoutrepeat visits to individual local authorities. Figure 4 shows the routing/zoning plan developed.

The regional road network was divided in to 8 zones. The division was generally based on boundariesformed by national routes. Estimates of lengths and number of routes in each zone are shown inTable 4.

The data collection of the road condition data (RCD) was completed over a 20 week period from Julyto October, 2011. The data collection of the skidding resistance data (SCRIM) outside Dublin Citywas completed over a 23 week period from July to November, 2011. The skidding resistance data onthe regional roads in Dublin City was collected from the 5th to 9th February, 2012.

8. REMEDIAL WORKS CATEGORIES

The primary output from of the 2011/12 Regional Road Pavement Condition Study was the length,average width and area of regional road in each county, and nationally, requiring various types ofremedial works. The four remedial works categories were:

o Road Reconstruction;o Surface Restoration;o Restoration of Skid Resistance, ando Routine Maintenance.

Road Reconstruction was defined to include reconstruction of existing road pavements, overlayingof existing road pavements with bound or unbound materials surface dressed, and raising of roadlevels to prevent flooding with provision of drainage. Surface Restoration was defined to includeimprovement of transverse and longitudinal drainage, pothole patching, restoration of road width and



strengthening of road edges as well as localised surface dressing of the repaired areas. Restorationof Skid Resistance covers the application of a surface treatment to restore adequate skid resistance.Routine Maintenance was defined to include road section lengths not requiring any of the other threeremedial work types. Road sections in this category would be in very good existing condition.

County Length (km)CARLOW 186

CAVAN 395

CLARE 632

CORK 1367

CORK CITY 38

DUBLIN CITY 163

DUN LAOIRE/RATHDOWN 101

DONEGAL 785

FINGAL 253

GALWAY CITY 37

GALWAY 845

KERRY 523

KILDARE 493

KILKENNY 421

LAOIS 349

LEITRIM 334

LIMERICK CITY 33

LIMERICK 501

LONGFORD 152

LOUTH 246

MAYO 624

MEATH 576

MONAGHAN 299

NORTH TIPP 403

OFFALY 393

ROSCOMMON 376

SLIGO 233

SOUTH DUBLIN 113

SOUTH TIPP 493

WATERFORD 386

WATERFORD CITY 40

WESTMEATH 307

WEXFORD 473

WICKLOW 444

13010

Table 3: Regional Road Length Surveyed by Local Authority



Figure 4: National Routing and Zoning Plan

Zone Description Number Length (m)1 Donegal, North Leitrim 47 830

2 West of N04, North of N06 (Connacht) 91 2142

3 North of N06, East of N04 (North Leinster) 111 2389

4 South of N24 (Cork, Kerry, South Limerick) 146 2935

5 Dublin, inside M50 50 305

6 West of N65/N52/M7 (Clare, Sth Galway, LimerickCity)

47 1100

7 West of M7/M8 (West Midlands) 59 1402

8 East of M7/M8 (East Midlands, South Leinster) 109 2362

Table 4: Survey Zones



8.1. ALLOCATION OF SAMPLE UNITS INTO MAINTENANCE CATEGORIES

In the 1996 and 2004 surveys of the non-national roads, the PCI and the contribution of individualdistress were used to assign road segments to the appropriate remedial works category (5) (7). In 2004,the PCI was supplemented by ride quality data (IRI) in assigning sections with poor or very poor ridequality to the road reconstruction category (i.e. sections with IRI > 8).

In the 2011/12 study of the regional roads, the machine based road condition data (RCD) of IRI, rutdepth and MPD, the skidding resistance SC data (SCRIM) and the visual rating (VR) using the 1 to 10rating system from the digital video were used to allocate the 100 metre sample units for eachRegional road into the 4 remedial works categories. On the safety side, both SCRIM (SC) andmacrotexture (MPD) were measured, giving better measures of the requirement for Restoration ofSkid Resistance than a visual survey can provide. On the shape side, longitudinal profile (IRI) andtransverse profile (rut depth) were measured directly by the RSP machine, these parameters give ameasure of distress types such as rutting, depressions and deformation that are the most difficult toconsistently identify visually from a video survey.

In addition, the Visual Rating system was developed specifically with the aim of mapping the 1 to 10Visual Rating to the desired maintenance categories as shown in Table 2. Thus, VR of 1 to 4 maps tothe Road Reconstruction category, VR of 5 and 6 maps to the Surface Restoration category, VR of 7and 8 maps to the Restoration of Skidding Resistance category, and VR of 9 and 10 maps to theRoutine Maintenance category. On this basis, a number of combinations of parameters wereconsidered when assigning the remedial works categories.

8.1.1. Road Reconstruction

The approach taken was to initially determine appropriate parameters for the Road Reconstructioncategory. There are two appropriate machine parameters related to structural performance, thewheelpath rut depth and the IRI. In addition, the Visual Rating value categories from 1 to 4 weredesigned to map to the Road Reconstruction category.

The 3 condition parameters and threshold levels used to assign 100m segments to the RoadReconstruction category were:

IRI > 8 OR Left Wheelpath Rut Depth > 25 mm OR Visual Rating of 4 or less

8.1.2. Surface Restoration

The primary criterion for inclusion in the Surface Restoration category was as follows:

IRI <= 8 AND Rut Depth <=25 mm AND Visual Rating of 5 or 6

The first two terms are to ensure that segments already selected for the Road Reconstructioncategory are not selected again. The Visual rating categories of 5 and 6 were designed to map to theSurface Restoration category.

In addition, 100 metre stretches with better Visual Rating, but relatively poor ride quality, wereincluded as follows:

IRI between 6 and 8 AND Rut Depth <=25 mm AND Visual Rating of 7 to 10



8.1.3. Restoration of Skid Resistance

The primary criterion for inclusion in the Restoration of Skid Resistance category was as follows:

IRI <=6 AND Rut Depth <=25 mm AND Visual Rating of 7 or 8

As before, the first two terms are to ensure that segments with Visual Ratings of 7 or 8 alreadyselected for Road Reconstruction or Surface Restoration are not selected again. The Visual Ratingcategories 7 and 8 were designed to map to the Skid Resistance category.

In addition, 100 metre stretches with better Visual Rating (9 or 10), but relatively poor skid resistanceas indicated by MPD or SC were included as follows:

IRI <=6 AND Rut Depth <=25 mm AND Visual Rating of 9 or 10 AND MPD <= 0.6 mm

IRI <=6 AND Rut Depth <=25 mm AND Visual Rating of 9 or 10 AND SC <= 0.30

8.1.4. Routine Maintenance

All other 100 metre segments not already allocated to one of the other three maintenance categoriesare included in this category. By a process of elimination, 100 metre stretches in this category havevery good visual rating (9 or 10), IRI values of less than 6, rut depth values of less than 25 mm, SCvalues greater than 0.30 and MPD values greater than 0.6 mm.

9. GENERAL STATISTICS NATIONAL RESULTS

The overall average values for each peformance parameter across the Regional road network areshown in Table 5. Figures 5 to 8 show the cumulative frequency plots for each of the conditionparameters of IRI, Rut, MPD, SC and VR, respectively.

Parameter Average

Average IRI (mm/m) 4.2

Left Rut (mm) 10.3

MPD (mm) 1.4

SCRIM Coefficient 0.50

Visual Rating 7.2

Table 5: Average Performance Parameters, 2011

Figure 5 shows the average IRI cumulative frequency plot for the Regional road network. It can beseen, for example, from Figure 5 that c. 20% of the regional road network has an IRI value of 2.3mm/m or less, c. 50% has an IRI value of 3.7 mm/m or less, and c. 90% of the network has an IRIvalue of 7.0 mm/m or less. The IRI values are quite evenly distributed across the network over therange shown, with the frequency curve being close to a straight line.



Figure 6 shows the left rut cumulative frequency plot for the Regional road network. Unlike the IRIdistribution curve, the left rut frequency curve is clearly curved, with almost 40% of the valuesmeasured less than 6 mm, and c. 10% of the values greater than 21 mm.

Figure 5: Average IRI Cumulative Frequency Plot

Figure 6: Left Rut Cumulative Frequency Plot

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Regional 2011 - Left Rut Cum. Frequency

Left Rut (mm)



Figure 7 shows a different distribution for the macrotexture parameter, MPD. There are c. 10% of themacrotexture measurements with a value of 0.7 mm or less. There is close to a uniform (straight line)distribution between 0.9 and 1.9 mm, with tails at the top and bottom of the distribution.

Figure 8 shows the cumulative frequency plot based on SCRIM Coefficient (SC). The SC distributionclearly has a long tail at the lower end, with relatively few values of 0.35 or less, and c. 10% of the 100metre average values having a value of 0.40 or less. Most of the values measured range between0.40 and 0.60, with another flattening out of the curve about 0.60.

Figure 7: Mean Profile Depth (mm) Cumulative Frequency Plot

Figure 8: SCRIM SC Cumulative Frequency Plot

0102030405060708090

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Regional 2011 - MPD Cum. Frequency

MPD (mm)

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Regional 2011 - SCRIM SC Cum. Frequency

SCRIM Coeff



Figure 9 shows a different distribution to the other parameters. First, this is a discrete distribution, withonly integer values between 1 and 10 used – all the machine parameters shown were continuous. It isclear that there are a very low percentage of 100 metre road sections on the Regional road networkwith Visual Rating values of 1, 2 or 3. The steepness of the curve between 7 and 9 shows that over40% of the entire network had a Visual Rating of either 8 or 9, indicating very good existing conditionsbased on a visual assessment of the regional road network.

Figure 9: Visual Rating Cumulative Frequency Plot

10. GENERAL STATISTIC FROM RESULTS BY COUNTY

Table 6 shows the average values of the machine and Visual Rating parameters in each localauthority.

It can be seen from Table 6 that there are significant variations in average road condition asmeasured by the various parameters across the local authorities. There are a number of factors thatmay influence the average value including underlying subgrade condition, pavement layerthicknesses, quality of material present and maintenance practices. In addition, some counties willshow better average results due to the reclassification of former National routes to regional routes asthe Motorway network expanded in the past few years.

Figures 10 to 14 show the National distribution across the counties for IRI, Rut, MPD, SC and VR,respectively.

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Regional 2011 - VR Cum. FrequencyVisual Rating



COUNTY IRI RUT SC MPD VisualCARLOW 3.3 8.8 0.45 1.3 7

CAVAN 3.8 10.0 0.53 1.4 7

CLARE 4.8 10.9 0.52 1.7 7

CORK 4.8 11.4 0.57 1.4 7

CORK CITY 4.3 4.2 0.51 1.4 8

DUBLIN CITY 4.8 3.9 0.55 1.1 7

DUN LAOGHAIRE 3.7 4.9 0.51 1.3 8

DONEGAL 4.7 9.9 0.56 1.4 8

FINGAL 3.8 7.0 0.50 1.2 7

GALWAY CITY 3.7 4.8 0.48 1.2 7

GALWAY 4.5 12.2 0.53 1.5 7

KERRY 4.3 11.9 0.58 1.5 7

KILDARE 3.3 6.2 0.49 1.3 8

KILKENNY 3.7 9.4 0.52 1.4 7

LAOIS 3.9 9.4 0.48 1.4 7

LEITRIM 3.4 10.0 0.60 1.4 8

LIMERICK CITY 3.4 3.8 0.44 1.2 8

LIMERICK 4.0 11.6 0.49 1.6 7

LONGFORD 3.2 8.7 0.53 1.4 8

LOUTH 2.9 6.5 0.50 1.3 8

MAYO 5.2 13.0 0.55 1.6 6

MEATH 3.7 8.2 0.50 1.4 8

MONAGHAN 3.3 8.2 0.55 1.2 7

NORTH TIPP 4.6 12.9 0.52 1.5 7

OFFALY 4.6 13.3 0.50 1.4 7

ROSCOMMON 3.6 10.3 0.53 1.5 7

SLIGO 4.0 11.5 0.56 1.5 7

SOUTH DUBLIN 3.4 4.6 0.49 1.4 8

SOUTH TIPP 4.4 11.5 0.51 1.5 7

WATERFORD 4.4 10.3 0.55 1.3 7

WATERFORD CITY 3.7 3.6 0.46 1.4 8

WESTMEATH 3.3 8.6 0.50 1.3 8

WEXFORD 4.4 12.3 0.45 1.3 6

WICKLOW 4.5 10.4 0.47 1.6 7

Table 6: Condition Parameters – Average Values 2011



Figure 10 shows the distribution of averagevalues of IRI. It can be seen that vast majorityof counties have an average IRI value ofbetween 3 and 5, with better (lower) valuestypically in the Eastern half of the country.

Figure 10: Average IRI Values byCounty - 2011

Figure 11 shows the distribution of averagevalues of left wheelpath rut depth across all localauthorities. Rut depth is an indicator of structuraldistress, with higher values indicating poorerstructural conditions. It can be seen that mostlocal authorities show average values of between8 and 12 mm, with better results typically in theurban authorities.

Figure 11: Average Rut Depth Values byCounty - 2011



Figure 12 shows the national distribution ofaverage MPD results, an indicator of the skidresistance available from the pavementmacrotexture. Higher values of MPD indicategreater drainage channels available at thepavement surface. The average values arelikely to be significantly influenced by thepercentage length of surface dressing usedwithin each local authority on the regionalnetwork, as surface dressing tends to yieldsignificantly higher MPD readings comparedwith most hot mix bituminous materials.

Figure 12: Average MPD by County -2011

Figure 13 shows the national distribution ofaverage SC values, an indicator of the skidresistance available from the pavementmicrotexture. Higher values of SC indicate greaterfrictional resistance available at the pavementsurface. The average values are likely to besignificantly influenced by the quality of surfacingmaterial available in the area, and by the age andaverage resurfacing cycle length in the localauthority.

Figure 13: Average SC Values by County -2011



Figure 14 shows the distribution of averagevalues of Visual Rating on the regional roadnetwork across the country. Higher values ofVisual Rating indicate better condition. It canbe seen from the figure that most localauthorities have an average Visual Ratingvalue of between 7 and 8, indicative of Goodoverall condition on average.

Figure 14: Average Visual Rating byCounty - 2011

11. COMPARISON BETWEEN THE 2011 AND 2004 SURVEYS

The VPCI survey methodology used in 2004, while broadly similar in approach to the Visual Ratingapproach used in 2011, has some significant differences in the final calculation of PavementCondition Index. In particular, the VPCI requires a detailed identification and quantification of eachpavement distress present in each 100 metres, while the Visual Rating approach is less detailed andmore focussed on the use of pavement distress to identify an appropriate maintenance remedialworks category. The VPCI is not directly comparable to the VR system, although both approaches aremeasuring similar conditions.

However, the ride quality parameter, IRI, can be used for direct comparison of the 2004 and 2011results. The IRI is machine-measured, and with proper calibration and quality control/assurance, theresults can be directly compared over time. The only caveat in this comparison is that the 2004 studywas based on stratified sampling of c. 15% of the regional road network, whereas the 2011 study isbased on a survey of the entire network, effectively a 100% sample. Given the statistical design of the2004 study, the results obtained can be directly compared with the 2011 study.

Table 7 shows the average IRI value for each local authority surveyed in 2004 and 2011. The urbanlocal authorities (City Councils) were not included in the 2004 survey and are accordingly omitted fromTable 7.

The average IRI has dropped in all local authorities between 2004 and 2011. The reduction rangesfrom 0.5 IRI points to 3.0 IRI points, with an overall average network IRI drop of 1.2 IRI points from2004 to 2011. The scale of the reduction is very significant in all local authorities, and represents a



clear improvement in ride quality on the regional road network across the country over the seven yearperiod. It should also be noted that many of the biggest drops in average IRI values are in localauthorities that had very high (poor) average IRI values in 2004. The average IRI values in 2004 atlocal authority level ranged from 3.4 to 7.1 mm/m IRI. The average values in 2011 at local authoritylevel ranged from 2.9 to 5.2 mm/m IRI, a significantly lower spread of values.

Figure 15 shows the cumulative frequency curves for both the 2004 and 2011 national surveys basedon average IRI. It can be seen from the figure that there has been a substantial improvement over theseven year period. Taking some examples, in 2004, c. 33% of the regional road network had an IRIvalue of 4 or less. In 2011, c. 57% of the regional road network had an IRI value of 4 or less. Similarly,in 2004, c. 14% of the regional road network had an IRI value greater than 8. In 2011, c. 6% of theregional road network had an IRI value of greater than 8. The improvements are clear across allranges of the IRI.

County 2004 2011 DifferenceCARLOW 3.9 3.3 0.6

CAVAN 4.6 3.8 0.8

CLARE 6.4 4.8 1.6

CORK 6.2 4.8 1.4

DLR 4.2 3.7 0.5

DONEGAL 7.1 4.7 2.4

FINGAL 4.5 3.8 0.7

GALWAY 5 4.5 0.5

KERRY 5.2 4.3 0.9

KILDARE 4.2 3.3 0.9

KILKENNY 4.2 3.7 0.5

LAOIS 5.2 3.9 1.3

LEITRIM 4.3 3.4 0.9

LIMERICK 5.4 4.0 1.4

LONGFORD 4.9 3.2 1.7

LOUTH 4 2.9 1.1

MAYO 5.9 5.2 0.7

MEATH 5.4 3.7 1.7

MONAGHAN 3.4 3.3 0.1

NORTH TIPP 6.4 4.6 1.8

OFFALY 5.7 4.6 1.1

ROSCOMMON 6.6 3.6 3.0

SLIGO 6.3 4.0 2.3

SOUTH DUBLIN 4 3.4 0.6

SOUTH TIPP 5.2 4.4 0.8

WATERFORD 5.8 4.4 1.4

WESTMEATH 4 3.3 0.7

WEXFORD 5.8 4.4 1.4

WICKLOW 5.7 4.5 1.2

Table 7: Average IRI for the 2004 and 2011 Surveys



Figure 16 shows a graphical representation of the distribution of average IRI values by local authorityin 2004 and 2011. The significant improvement locally and nationally is evident from the figure, with asignificant “greening” of the 2011 map as the average IRI values drop over the seven year period.

Figure 15: Average IRI – 2004 and 2011 Comparisons

Figure 16: 2004 and 2011 IRI comparisons by County

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IRI 2011 IRI 2004



12. NATIONAL REMEDIAL WORKS REQUIREMENT

There were over 130,000 sample units, each 100 metres in length, on the regional road network. Thebasis for the allocation of the regional road network in to the 4 remedial works categories based onthe RCD (IRI, rut depth & MPD), SCRIM (SC) and visual rating (VR) criteria has already beendescribed in this paper. Table 8 and Figure 17 show, for the 2011 study, the percentage length ofRegional Roads nationally in each of the 4 maintenance categories.

Table 9 shows the percentage length of regional road in each of the 4 remedial works categories in2004. Although not directly comparable due to the changes in methodology, it can be seen that thesurface restoration and routine maintenance categories have quite similar percentages in 2004 and2011, while the Road Reconstruction category percentage is significantly reduced from 24% in 2004to 15% in 2011, and the Restoration of Skid Resistance category shows a commensurate increase.

Remedial Work Type PercentagesRoad Class Routine Maint. Skid Resist. Surf. Rest. Reconstruction

Regional 21.8% 39.4% 23.7% 15.1%

Table 8: Maintenance Categories - % in 2011 Study

Remedial Work Type PercentagesRoad Class Routine Maint. Skid Resist. Surf. Rest. Reconstruction

Regional 24.7% 29.6% 21.7% 23.9%

Table 9: Maintenance Categories - % in 2004 Study

Figure 17: 2011 Remedial Works Categories

RoadReconstruction,1898km, 15%

SurfaceRestoration,

3037km, 23%

SkidResistance,

5226km, 40%

RoutineMaintenance,2849km, 22%

Regional Road Network - 2011

Road Reconstruction

Surface Restoration

Skid Resistance

Routine Maintenance



Only Road Reconstruction remedial works will improve the IRI over significant lengths under theDTTAS remedial works category definitions. It is recommended that better IRI standards should beaimed for and applied over time to have a specific, measurable performance parameter reflecting roaduser expectations. It is proposed that over time, the maximum threshold levels should move to aposition where Road Reconstruction is indicated if the IRI value is greater than 6. As indicated earlierin this paper, the current position is that Road Reconstruction is indicated if the IRI value is greaterthan 8, consistent with the approach adopted in 2004. Ultimately, application of these maximumthreshold levels would lead to significant improvements in the overall ride quality levels on theregional road network, and would also form a basis for further improvements in the future.

13. REMEDIAL WORKS REQUIREMENTS BY COUNTY

Table 10 shows the percentage of regional road length in each of the 4 remedial works categories forall of the local authorities based on the 2011 survey. At local authority level, there is considerablevariability in the distribution across the remedial works categories with the urban local authoritiesgenerally have a relatively low percentage of road length in the Road Reconstruction category.

There is a very notable difference across the rural local authorities. A number of rural local authoritieshave less than 10% of the regional road length in the Road Reconstruction category, with a smallnumber having less than 5% of the length in the Road Reconstruction category. Most rural authoritieshave between 10 and 20% of the regional road length in the Road Reconstruction category, with asmall number having greater than 20% in this category.

Table 11 shows a comparison of the percentage length in Road Reconstruction for each rural localauthority surveyed in 2004 and 2011. It can be seen from Table 11 that generally there has been areduction in the percentage length in the Road Reconstruction category in almost all local authorities.The size of the reduction is very variable, and is also related to the percentage in the RoadReconstruction category in 2004. Clearly, local authorities with a relatively low percentage in the RoadReconstruction in 2004 have much less scope to produce large reductions compared with localauthorities that had a very high percentage in the category. In 2004, the percentage values rangedfrom 8% to 48%, with an average value of 24%. There is a significantly narrower range in 2011, from3% to 28%, with an average value of 15%.

Figure 18 shows the distribution of Road Reconstruction percentage across the country in 2004 and2011. The reducing amount of Road Reconstruction required, seen visually by the reduction in redand increase in green, is clearly evident over the seven year period.



County ROADRECON.

SURFREST.

SKIDRESIST.

ROUTINEMAINT.

CARLOW 8.6 21.2 45.5 24.7CAVAN 7.8 21.3 53.4 17.5CLARE 13.3 29.2 43.1 14.4CORK 18.5 23.8 41.4 16.4

CORK CITY 5.8 17.1 51.1 26.1DUBLIN CITY 10.2 34.9 36.2 18.7

DLR 2.7 16.6 32.8 47.9DONEGAL 13.0 22.5 42.1 22.4

FINGAL 9.0 26.1 37.4 27.4GALWAY CITY 3.2 30.5 36.4 29.9

GALWAY 19.4 27.6 37.7 15.4KERRY 12.7 23.9 47.2 16.2

KILDARE 9.1 19.0 40.5 31.5KILKENNY 8.9 14.9 55.1 21.1

LAOIS 13.7 27.5 41.2 17.6LEITRIM 6.7 12.2 42.5 38.6

LIMERICK CITY 1.2 21.8 54.5 22.5LIMERICK 9.0 24.5 50.7 15.8

LONGFORD 3.4 13.7 64.2 18.6LOUTH 2.6 8.5 52.4 36.5MAYO 26.1 37.0 27.5 9.4

MEATH 10.9 20.3 34.1 34.7MONAGHAN 4.2 16.2 60.3 19.3NORTH TIPP 23.0 29.4 29.0 18.7

OFFALY 25.3 26.5 26.1 22.1ROSCOMMON 14.3 17.8 34.9 33.0

SLIGO 19.8 20.4 36.3 23.5SOUTH DUBLIN 5.9 8.6 33.7 51.8

SOUTH TIPP 13.8 27.6 35.6 23.0WATERFORD 19.2 24.3 38.9 17.6

WATERFORD CITY 3.2 19.1 30.5 47.1WESTMEATH 8.4 19.7 35.5 36.3

WEXFORD 27.8 25.6 33.9 12.7WICKLOW 20.5 19.1 30.1 30.4

Table 10: Percent Length of Regional Roads in each Remedial Work Category



County 2004 2011 DropCARLOW 14.5 8.6 5.9CAVAN 9.5 7.8 1.7CLARE 26.2 13.3 12.9CORK 32.0 18.5 13.5

DUN LAOGHAIRE 12.0 2.7 9.3DONEGAL 39.1 13.0 26.1

FINGAL 17.2 9.0 8.2GALWAY 22.3 19.4 2.9KERRY 22.6 12.7 9.9

KILDARE 9.8 9.1 0.7KILKENNY 9.1 8.9 0.2

LAOIS 16.9 13.7 3.2LEITRIM 8.1 6.7 1.4

LIMERICK 9.4 9.0 0.4LONGFORD 13.7 3.4 10.3

LOUTH 21.9 2.6 19.3MAYO 34.6 26.1 8.5

MEATH 34.8 10.9 23.9MONAGHAN 7.7 4.2 3.5NORTH TIPP 18.6 23.0 -4.4

OFFALY 27.4 25.3 2.1ROSCOMMON 28.8 14.3 14.5

SLIGO 41.4 19.8 21.6SOUTH DUBLIN 10.6 5.9 4.7

SOUTH TIPP 25.8 13.8 12.0WATERFORD 24.0 19.2 4.8WESTMEATH 10.9 8.4 2.5

WEXFORD 47.5 27.8 19.7WICKLOW 23.1 20.5 2.6

Table 11: Percent Length of Regional Roads in Road Reconstruction: 2004 and 2011

Figure 18: Road Reconstruction % - 2004 and 2011



14. MAPROAD PAVEMENT MANAGEMENT SYSTEM

A key part of the 2004 Non-National Road Needs Study was to recommend a single PavementManagement System (PMS) to be implemented in all local authorities in Ireland. After acomprehensive study of available off the shelf (OTS) and bespoke systems, it was recommended thatthe optimal solution was to develop the MapRoad GIS package to provide increased functionality.

MapRoad is a suite of software products, developed by the Local Government Management Authority(LGMA) and used by Local Authorities to manage a range of road-related data. The core modulesinclude:

Road Network: This is the core Module managing data associated with the road itself; itsgeographical location, its name, width, length, date taken in charge.

Road Management: This module manages data associated with maintaining the road such as surveyand inspection data, works carried out data and work programme creation data.

Road Accident: manages data associated with accidents such as their location and all data fromCT68/Garda Accident Report Form. The module allows automatic import of NRA data, produces lowcost proposal forms and facilitates accident analysis.

Road Bridge: manages data associated with bridges such as inspection data, inventory data andworks carried out, including import of NRA Bridge inventory Data.

Road Hazard: manages data associated with claims made to Local Authorities. Allowing inspectionsand works carried out to be recorded and reports and acknowledgment letters to be created.

Specifically the PMS system addresses the following requirements:

The need to demonstrate effective investment and the resulting benefits of such investmenton the road network as set out in the 2005 Department of Finance document ‘Guidelines forthe Appraisal and Management of Capital Expenditure Proposals in the Public Sector’.

The need to demonstrate that the investment in the road infrastructure is delivering the opti-mum value for money.

Demonstrating the need for investment to maintain the value in the road asset. Increased reporting requirements of the NRA and Department of Transport. Manage Local Authority expenditure on roads and retain a history of that expenditure.

Implementation of Phase 1 of the project is almost completed and includes the ability to record thehistory of Works Interventions and creation of a Roads Programme. Additionally a browser (web)version has been developed which incorporates open source mapping.

Phase 2 development is underway which includes:

Import & display Mechanical Survey Data including all of the results and video from the 2011Regional Roads survey

Mobile Applications for collection of Visual Condition Data in the field based on the 1-10 sur-vey methodology used in the 2011 Regional Roads survey

Creation of single National dataset of Road Network Finance Module: Creation of Roads Programme, Setup of same in Financial System, Report-

ing / Grant Application & Returns Completing the development of the road-works licensing module which supports the process-

es involved in the issuing of Road Opening Licences by both the NRA and Local Authorities toTelecomm and other Utility Companies, and its subsequent implementation.



The successful development of a PMS specifically for Irish local authorities, and in particular the webbrowser version that allows access to the data, mapping and reporting functions from all localauthority computers connected to the system, will enhance and improve the cost-effectivemanagement of the pavement network and annual Roads programmes.

15. SUMMARY AND CONCLUSIONS

The Department of Transport, Tourism, Arts and Sport (DTTAS) and the National Roads Authority(NRA) commissioned PMS Pavement Management Services Ltd. to carry out a pavement conditionstudy on the entire Regional road network in 2011. The pavement condition study involved the use ofmachine surveys to collect road condition data, skidding resistance data and digital imagery on theRegional road network. A total of 13,055 kilometres comprising 673 regional road routes wassurveyed in one direction as part of the 2011 study.

The outturn condition parameters comprised a number of key pavement performance indicators. Thekey indicators were visual rating (VR), international roughness index (IRI), rut depth, mean profiledepth (MPD) and SCRIM coefficient (SC). The condition parameters were reported for each 100metre length of the entire regional road network. The remedial works categories are RoutineMaintenance, Surface Restoration, Road Reconstruction and Restoration of Skid Resistance.

The assignment of each surveyed sample unit to one of the remedial works categories was primarilybased on the machine data parameters of IRI, rut depth, MPD and SC. In addition, the VR data wasalso used to modify the results derived from the machine parameters.

A study of the pavement condition of the Non-National road network was carried out previously in2004. This study involved a data collection effort of c. 8,000 km of road, covering not only regionalroads, but also local primary, local secondary and local tertiary roads. When the 2004 and 2011survey results are compared in terms of ride quality (IRI), it is clear that there has been a substantialimprovement in ride quality on the Regional road network over the seven year period.

It can also be seen that the average IRI has dropped in all local authorities between 2004 and 2011.The reduction ranges from 0.5 IRI points to 3 IRI points, with an overall average drop of 1.2 IRI points.The scale of the reduction is very significant in all local authorities.

Nationally, the percentage length of the Regional road network in the Road Reconstruction categoryhas dropped very significantly from 24% in 2004 to 15% in 2011.

At local authority level, there is considerable variability in the distribution across the remedial workscategories. The urban local authorities generally have a relatively low percentage of road length in theRoad Reconstruction category. Most rural authorities have between 10 and 20% of the regional roadlength in the Road Reconstruction category, with a small number having greater than 20% in thiscategory.

The successful development of the MapRoad PMS specifically for Irish local authorities, and inparticular the web browser version that allows access to the data, mapping and reporting functionsfrom all local authority computers connected to the system, will enhance and improve the cost-effective management of the pavement network and annual Roads programmes. All of the data, videoand maintenance category assignment carried out in the 2011 pavement condition study is availableto the local authorities through the MapRoad PMS.



16. ACKNOWLEDGEMENTS

The authors would like acknowledge and thank Dominic Mullaney and John McCarthy from theDepartment of Transport, Tourism and Sport, and John Fitzsimons from the National Roads Authority,for their help and technical assistance in the successful completion of the 2011/2012 Regional RoadPavement Condition Study.



REFERENCES

(1) National Development Plan 2007-2013, www.ndp.ie(2) Department of Transport, Tourism and Sport website, www.dttas.ie(3) DTTAS/NRA Project Specification “Contract for the Collection and Processing of Road Con-

dition and Skidding Resistance Data – Regional Roads”, March 2011(4) Regional Road Network Pavement Condition Study Report by PMS Pavement Management

Services Ltd., Department of Transport, Tourism and Sport (DTTAS)/National Roads Authori-ty (NRA), May 2012.

(5) Condition of Road Pavement Study by Ove Arup & Partners Ireland, PMS Pavement Man-agement Services Ltd. and Jennings O’Donovan & Partners, Department of the Environment,June 1997

(6) Pavement Management of Secondary Roads in Ireland, Dr. Kieran J. Feighan, 4th Interna-tional Conference on Managing Pavements, Durban, South Africa, 1998.

(7) Non-National Roads Pavement Condition Study Report by PMS Pavement ManagementServices Ltd. and RPS Group, Department of the Environment, Heritage and Local Govern-ment, December 2004.

(8) Non-National Roads - Pavement Condition and Pavement Management Studies, Dr. KieranFeighan, PMS Pavement Management Services and Alan Thomson, RPS Consulting Engi-neers, Institution of Engineers of Ireland, 2004.

(9) ASTM E 950-98 (2004), “Standard Test Method for Measuring the Longitudinal Profile ofTravelled Surfaces with An Accelerometer Established Inertial Profiling Reference”

(10) AASHTO PP 37-04 “Standard Practice for Determination of International Roughness Index(IRI) to Quantify Roughness of Pavements”

(11) World Bank Technical Paper #46 “Guidelines for Conducting and Calibrating Road Rough-ness Measurements”.

(12) Clause 921 of the NRA Specification for Road Works 900 Series (March 2011) “Surface Ma-crotexture of Bituminous Surface Courses”

(13) IS EN ISO 13473: Part 1: 2004 “Characterization of Pavement Texture by Use of SurfaceProfiles; Determination of Mean Profile Depth”

(14) BS7941-1: 2006 Methods for measuring the skid resistance of pavement surfaces - Part 1:Sideway-force coefficient routine investigation machine, British Standards Institution, London,England, 2006.

(15) Standard Recommendation SR CEN/TS 15901-6: 2009 Road and airfield surface character-istics – Part 6: Procedure for determining the skid resistance of a pavement surface bymeasurement of the sideway force coefficient (SFCS): SCRIM, National Standards Associa-tion of Ireland (NSAI), 2009.

(16) Description of Duties and Services to be Provided in Respect of Term Contract for the Col-lection of Road Condition and Skid Resistance Data – Project Specification, National RoadsAuthority (NRA), Ireland, April 2010.

(17) SCRIM Operating and Maintenance Manual, W.D.M. Limited, North View, Staple Hill, Bristol,England, February 2011

(18) Design Manual for Roads and Bridges, Volume 7: Pavement Design and Maintenance, Sec-tion 3, Part 1, NRA HD28/11– Management of Skid Resistance, National Roads Authority(NRA), November 2011.

(19) PASER Asphalt Roads Manual, Wisconsin Transport Information Center, University of Wis-consin Madison (2002).

(20) Flexible Roads Manual - Pavement Surface Evaluation and Rating on Irish Roads, Depart-ment of Transport, Tourism and Sport, May 2012.

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