Alignment Airport Site Design Process

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The Design Process of a Transportation Facility

Developing a transportation facility is a mixture of technical, legal, and

political elements. Some facilities such as Airports may take more than

10 years from the inception to the completion of the facility, but a few

others (eg. Bypass road) might take less than a year. Broadly the

process of designing a transportation facility can be divided into

planning, traffic design, location, physical design. Some of these phases

need to repeat many times during the process. These steps are

followed with the construction phase. Specific tasks involved in the

design process are listed below. Figure 3.1 (handout) shows many stepsare iterative.

1. Deciding the type of facility: what facility or facilities areneeded? For example, should we go for metro, bus rapid transit

system (BRTS), monorail?

2. Demand analysis: predict the traffic demand (no. of persons,number of vehicles, or amount of freight) for the facility. Steps 1

and 2 are interdependent.

3. Traffic performance analysis: After finalizing the type of facility,the anticipated traffic demand with respect various features of

the facility is analyzed. This step includes finding capacities and

evaluating the performance of the system. For examples, how

much aircraft traffic will be handled by one run way, two

runways, etc and under what level of service.

4. Size of the facility: Based on the analysis in the step 3 (Trafficperformance analysis) the size of the facility is finalized. For

example, deciding the number of runways, number of lanes, or

number of railway tracks.


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5. Location of the facility: Involves studying various alternativesand selecting the best alternative.

6. Configuration and/or orientation of the facility: deciding thedirection of runways, selecting the highway interchange type

7. Physical design standards: Various design standards areavailable. This is a policy matter for the organization designing

the system.

8. Geometric design: Developing horizontal alignment and verticalalignment

9. Design auxiliary systems: designing drainage, lighting, trafficcontrol etc.

10. Design surface or guideway: design of pavement or design oftrack

11. Estimate construction cost: detailed cost estimate is necessarybefore the bid process begin.

12. Analyze project impacts: study environmental impacts, socialimpacts of the facility

13. Evaluate design: designing a facility is an iterative process andneeds evaluation at various stages for different criteria such as

physical feasibility; economy; and social, environmental,

economic impacts.


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Road Classifications in India

Different criteria for classification

Based on the usage during different seasons

All-weather roads: able to be used throughout the year except atmajor river crossings where limited interruption during monsoon

is permissible

Fair-weather roads: traffic may be interrupted at stream crossingsduring monsoon

Based on the type of carriage way

Paved road: hard pavement course (at least water boundmacadam)

Unpaved road: earth and gravel roadsBased on the Location and Function

1)Primary systema.Expresswaysb.National highways (NH)

2)Secondary Systema.State highways (SH)b.Major district roads (MRD)

3)Tertiary system or rural roadsa.Other district roads (ODR)b.Village roads


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Classification of Urban Roads

i) Arterial roadsii) Sub-arterial roadsiii) Collector streets : Collects and distribute traffic from and to

local streets

iv) Local Streets :


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Highway Alignment

Fixing centre line of a highway proposed between two points

Requirements: Short:

o as straight as possible Easy:

o Easy to construct and maintaino Easy to travel

Safe:o Safe for construction and maintenanceo Safe geometric features

Economical:o Construction cost, maintenance cost, and vehicle operating

cost should be minimum

Factors affecting highway alignment

a)Obligatory points:o Obligatory points through which the road alignment must

pass. Eg. Intermediate towns, bridge site, etc

o Obligatory points through which the road should not pass.Eg. Religious places, costly structures, unstable soils, lake

b)Traffic demand:o The alignment should suit the traffic demand

c)Geometric design:o Requirements for gradient, curve radius, sight distances, etc

d)Economic consideration:


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o The final alignment should be economical with respect toconstruction, maintenance, and vehicle operating costs

e)Other consideration:o Drainage considerationo Hydrological considerationo Political factorso Monotony

Engineering surveys for highway location

a)Map study:Likely routes can be located by studying the topographical map of

the area. In India the topographical maps are available with the

Survey of India.

b)Reconnaissance:o Field investigation of a broad stretch of land along the

alignments located on the map

o Very simple instruments are usedo Based on the reconnaissance, the alignments marked on the

map can be altered or changed completely.

c)Preliminary surveyo Collected all the necessary physical information of the

various alternative alignments proposed after

reconnaissance

o Quantity of earth work for each alignment is estimatedo Different alignments are compared based on various

parameters

o The best alignment is finalizedd)Detailed survey:

o Final location and detailed survey of the best alignment


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Railway Alignment

Requirements

New alignment should serve the purpose for which the railwayline is being planned

The alignment should be economical It should be as short as possible The alignment should result in the minimum construction,

maintenance, and operating costs

It should provide maximum safety during and after construction The alignment should able to provide visually pleasant journey

Factors affecting Alignment

Choice of gauge: In India trains run on three different gauges:Broad gauge (1676 mm), Metre gauge (1000 mm), and Narrow

gauge (762 mm). Delhi Metro uses Standard gauge (1435 mm). Asper the recent policy of the Government of India, all new railway

lines should be Broad gauge. However, there was a lot of debate

in finalizing the gauge for Delhi Metro. The difference in opinion

existed during the planning of Mumbai metro also. The choice of

gauge has significant impact on the route selection.

Obligatory points: The points through which the railwayalignment must pass for some political, commercial, or strategic

reasons.

o Important cities and townso Major bridge sites and river crossingso Existing passes and saddles in hilly terrain


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o Sites for tunnelsThe points through which the alignment should not pass include

religious and historical monuments.

Topography of the region Geometric standards: requirements of geometric standards such

as gradient, curve radius for the safe and comfortable journey

Geological formation: The alignment should pass through a goodand stable soil formation

Effect of flood and climate: The alignment should pass throughareas which are not likely to get flooded.

Proximity to labour and material: This will reduce theconstruction cost

Location of Railway stations and yards: these should be locatedon level stretches

Cost: The alignment should result in minimum construction,maintenance, and operating costs

Traffic demand: The alignment should able to attract maximumdemand.

Economic consideration: The alignment should be economicallyfeasible.

Political consideration: The alignment should not pass throughforeign soil or controversial border areas.


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Airport Site Selection

The following factors affect the airport site selection

1)Type of development of the surrounding area:o Airport generates noiseo Should not be close to residential and school areas

2)Atmospherical and Meteorological conditions:o Presence of fog, haze, and smoke reduces visibility

3)Accessible to ground transportation:o At some existing airports often the time spent in ground

transportation is more than the air time

o Ground transportation to and from airport should beefficient

o Should able to handle airport peak hour demand4)Availability of land for expansiono Sufficient land should be available for the future expansion

of the airport

o Airport size at any time is usually depends on Type of aircrafts that will operate from the airport Passenger demand

Meteorological conditions Elevation of the airport site

5)Presence of other airports and availability of airspaceo Sufficient distance away from the existing airports


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o Aircrafts enough airspace for maneuvering during congestedperiod and during poor visibility

6)Surrounding Obstructionso High rise structures not allowed in the airport surrounding

7)Cost of Constructiono If other conditions are satisfied, a site with the minimum

construction cost is selected

8)Availability of Utilitieso Water, fuel, electricity, etc should be available easily

9)Closeness to the demand servedo Airport should be as close as possible to the point of

demand

10) Landuse planningo A site selected should be in accordance with the land-use

planning for a city or a region

11) Environmental impact assessmento Effect on air quality, noise level, ecological process, and

demographic development should be minimum

12) Economic and financial feasibilityo Airport should generate enough revenue to cover all costs

and preferably make some profit

Documents

Alignment Airport Site Design Process