Transportation Sample Chapter

8/11/2019 Transportation Sample Chapter

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TRANSPORTATION

ENGINEERING

Universities Press

Railways, Airports, Docks & Harbours

R Srinivasa Kumar


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Universities Press (India) Private Limited

Registered Office

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Hyderabad 500 029 (A.P.), India

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Universities Press (India) Private Limited 2014

First published 2014

Cover and book design

Universities Press (India) Private Limited 2014

ISBN 978 81 7371 924 0

All rights reserved. No part of the material may be reproduced or utilised in any form, or by any means,

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without written permission from the publisher.

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Published by

Universities Press (India) Private Limited

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facturers names appear/are used in this book only because they are considered essential to the object of subject

discussion and do not necessarily constitute an endorsement of the product by the author or the publisher.


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Contents

Preface ix Acknowledgements x

1 Introduction to Railway Engineering 1

1.1 Introduction 1

1.2 Classification of Routes 1

2 Components of a Permanent Way 4

2.1 Introduction 4

2.2 Rails 6

2.2.1 Function of Rails 6

2.2.2 Types of Rails 6

2.2.3 Brand Mark on Rails 8

2.3 Coning of Wheels 8

2.4 Creep of Rails 8

2.4.1 Effects of Creep 9

2.4.2 Theories Related to Creep 9

2.4.3 Measurement of Creep 11

2.4.4 Correction of Creep 11

2.4.5 Measures to Reduce Creep 11

2.5 Rail Joints 12

2.6 Wear of Rails on Curves 142.7 Cutting of Rails on Curves 14

2.8 Bending of Rails on Curves 14

2.9 Welding of Rails 15

2.10 Sleepers 16

2.10.1 Functions of Sleepers 16

2.10.2 Types of Sleepers 17

2.10.3 Sleeper Density 25

2.10.4 Aging of Sleepers 25

2.11 Rail Fastenings 26

2.12 Ballast 302.12.1 Types of Ballast 30

2.12.2 Geometric Parameters of Ballast 32

2.13 Formation 33


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iv Transportation Engineering

3 Geometric Design of a Railway Track 353.1 Introduction 35

3.2 Gradients 35

3.3 Compensation of Grade on Horizontal Curves 37

3.4 Horizontal Curves 37

3.4.1 Extra Clearance on Curves for High Speed Routes 40

3.4.2 Cant and Related Terminology 40

3.4.3 Determination of Cant or Superelevation 41

3.4.4 Transition Curve 44

3.4.5 Safe Speed on Horizontal Railway Curves 45

3.4.6 Length of a Transition Curve 463.4.7 Elements of a Transition Curve 48

3.4.8 Length of Transition Connecting Two Circular Curves of a Compound Curve 53

3.4.9 Length of Transition Connecting Two Circular Curves of a Reverse Curve 53

3.5 Vertical Curves 54

3.5.1 Types of Vertical Curves 54

4 Points and Crossings of Railway Tracks 57

4.1 Points and Crossing (Turnouts) 57

4.2 Terminology 58

4.3 Essential Requirements of a Good Crossing 61

4.4 Types of Crossings 61

4.5 Design of Turnout Components 66

5 Signalling and Interlocking of Railway Tracks 73

5.1 Introduction to Signalling 73

5.2 Objectives of Signalling 74

5.3 Classification of Signals 75

5.4 Classification of Stations 79

5.5 Quadrant Aspect of a Semaphore Signal 80

5.5.1 Two Aspect Signalling (TAS) 80

5.5.2 Multiple Aspect Signalling (MAS) 815.6 Signalling Systems 84

5.6.1 Mechanical Signalling System 84

5.6.2 Electrical Signalling System 87

5.7 System for Controlling Train Movement 87

5.8 Interlocking 91

5.8.1 Fundamental Principles of Interlocking 92

5.8.2 Types of Interlocking 92

5.9 Modern Signalling Installations 95

6 Introduction to Airport Planning and Design 1006.1 Introduction 100

6.2 The International Civil Aviation Organization (ICAO) 100

6.3 The Federal Aviation Administration (FAA) 101


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Contents v

6.4 Civil Aviation Safety Administration (CASA) 1026.5 Airports Authority of India (AAI) 102

6.6 Airport Master Plan 103

6.7 Airport Site Selection 105

6.7.1 Concept of Zoning Laws 109

6.8 Terminology 110

6.9 Aircraft Characteristics Affecting Design of Airport 117

6.9.1 Size of Airplane/Aircraft 117

6.9.2 Length of Aircraft 118

6.9.3 Wing Span 118

6.9.4 Wheel Base 1186.9.5 Gear Tread or Wheel Track or Landing Wheel Track or Landing Wheel Gear 118

6.9.6 Landing Gear Tread 118

6.9.7 Minimum Turning Radius 119

6.9.8 Weight of Aircraft or Maximum Structural Take-offWeight (MSTOW) 120

6.9.9 Combined Effect of Aircraft Movement 120

6.9.10 Landing Gear Tread versus Gross Weight 122

6.9.11 Ground Speed or Cruising Speed 122

6.9.12 Air Speed 122

6.9.13 Jet Blast 122

6.9.14 Surface Friction of Runway 122

6.9.15 Summary 124

7 Classification of Airports 127

7.1 Airports Categorisation 127

7.2 Categorisation of Airports by FAA 127

7.3 Airport Classification Based on Operational Characteristics 128

7.3.1 Classification of Airports by FAA 128

7.3.2 Classification of Aerodromes by ICAO 129

7.4 Concluding Remarks 130

8 Orientation of Runways 1318.1 Introduction 131

8.1.1 Atmospheric Conditions Affecting Planning and Orientation of Runways 131

8.2 Configurations of Runways 133

8.2.1 Designation of Runways 135

8.3 Wind Rose Diagrams 135

9 Design of Runway Length 145

9.1 Introduction 145

9.2 Estimation of Design Runway Length by FAA (AC 150/5325-4B, 2005) 145

9.3 Estimation of Design Runway Length by ICAO (Part 1, Doc 9157, AN/901, 2006) 154

10 Geometric Components of the Runway and Taxiway System 163

10.1 Basic Components of a Runway 163


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vi Transportation Engineering

10.2 Declared Distances Associated with a Runway (ICAO 2006; CASA 2012) 16310.3 Geometric Parameters of Runway and Taxiway 165

10.3.1 Runway 165

10.3.2 Taxiway 169

10.4 Instrument Landing System (ILS) 171

11 Airport Visual Aids 174


11.2 Runway Markings 174

11.3 Taxiway Markings 177

11.4 Airport Signs 179

11.5 Approach Lighting System (ALS) 186

11.6 Other Lighting Systems 193

12 Airport Terminal Area and Air Traffic Control System 196

12.1 Terminal Area 196

12.2 Components of a Terminal Building 197

12.3 Air Traffic Control (ATC) 197

13 Design of Runway Pavements 202


13.2 Structural Functions of Pavements 20213.3 Types of Pavements 203

13.3.1 Flexible Pavements 204

13.3.2 Rigid Pavements 204

13.3.3 Composite Pavements 206

13.4 Design Factors 208

13.4.1 Distribution of Aircraft Load on to the Pavement 208

13.4.2 Equivalent Single Wheel Load (ESWL) 208

13.4.3 Sub-grade Strength 210

13.4.4 Pavement Material Characteristics 210

13.4.5 Other Factors 21113.5 Overview on Airport Pavement Design Methods 212

13.6 Design Methods for Flexible Pavements 213

13.6.1 Unified Facilities Criteria (UFC) System or US Army Corps Methods

(UFC, 2001) 213

13.6.2 FAA Design Method (FAA AC 150/5320-6E on

Airfield Pavement Design and Evaluation) 217

13.7 Design Methods for Rigid Pavements 219

13.7.1 Unified Facilities Criteria (UFC) System Based on Westergaards

Stress Model (UFC 2001) 220

13.7.2 Portland Cement Association (PCA) Method 22313.7.3 Federal Aviation Administration (FAA) Method 225

14 ACNPCN System of Rating Aerodrome Pavements 228


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Contents vii

14.1 Introduction (ICAO 1989) 22814.2 Overview on Mathematical Models 230

14.3 Determination of ACN of an Aircraft 230

14.4 Uses of ACNPCN Aerodrome Rating System 233

14.5 Overloading Operations 233

15 Airport Pavement Drainage Systems 235


15.1.1 Influence of Moisture Fluctuations during Different Seasons 235

15.1.2 Frost Action 237

15.2 Drainage Considerations 238

15.3 Design Details of Surface Drainage System 23815.3.1 Estimation of Design Run-off 239

15.3.2 Hydraulic Design 242

15.3.3 Types of Curb Channels and Gutter Channels 245

15.3.4 Design of Curb Channel or Gutter Channel 246

15.4 Design of Sub-surface Drainage System 251

15.4.1 Sources of Sub-surface Water 252

15.4.2 Estimation of Quantity of Sub-surface Water to be Drained-off 252

15.4.3 Estimation of Quantity of Sub-surface Water due to Infiltration (Qi) 252

15.4.4 Determination of Coefficient of Permeability 254

15.4.5 General Design Criteria on Drainage Layer 25615.4.6 Edge Drain or Longitudinal Collector Drain or Draw Down Drain 258

15.4.7 Perforation Criteria of a Longitudinal Drain Pipe 259

16 Failures and Evaluation of Airport Pavements 263

16.1 Introdution 263

16.2 Airfield Pavement Failures 263

16.2.1 Categorisation of Distresses in Asphalt Concrete Pavement 263

16.2.2 Categorisation of Distresses in Cement Concrete Pavement 263

16.2.3 Identification, Causes and Measurement of Distresses 264

16.3 Technical Evaluation and Strengthening of Airfield Pavements 265

16.4 Structural Evaluation of Runway Pavements 26616.4.1 Structural Evaluation of Runway/Taxiway Pavement by

Testing with Heavy Weight Deflectometer (HWD) 268

16.5 Runway Pavement Condition Surveys 271

16.5.1 Concept of Pavement Condition Index (PCI) 271

16.6 Measurement of IRI Based on Quarter Car Model 273

16.7 Introduction to Ground Penetrating Radar (GPR) 275

16.8 Frictional Evaluation of Runway Pavement Surface 276

16.8.1 Introduction to Pavement Surface Friction 276

16.8.2 Friction Indices 277

16.8.3 Types of friction 27816.8.4 Skid Resistance/Friction Measurement Methods 280

16.9 Runway Surface Friction Models 280

16.9.1 Rado IFI Model 281


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viii Transportation Engineering

16.9.2 Canadian Runway Friction Index (CRFI) 28216.9.3 International Runway Friction Index (IRFI) 283

17 Maintenance of Airport Pavements 286


17.2 Maintenance and Rehabilitation of Airfield Pavements 286

17.2.1 Interpretation of a Condition Rating 286

17.2.2 Structural Overlay with Reference to HWD Test Results 287

17.2.3 Surface Texturing Practices to Improve Skid Resistance 287

17.3 Maintenance and Rehabilitation Alternatives for Flexible Pavements 289

17.4 Maintenance and Rehabilitation Alternatives for Rigid Pavements 293

18 Planning and Layout of Docks and Harbours 296


18.2 Harbours 296

18.2.1 Harbour planning principles 296

18.2.2 Terminology 297

18.2.3 Layout of a harbour 297

18.2.4 Classification of harbours 298

18.3 Ports 299

18.3.1 Requirements of a Good Port 300

18.3.2 Classification of Ports 300

18.3.3 Port Terminals 301

18.4 Docks 301

18.4.1 Classification of Docks 301

18.5 Transit Sheds and Warehouses 302

19 Construction and Maintenance of Docks and Harbours 305


19.2 Construction of Quay Walls 305

19.3 Construction of Breakwaters 306

19.4 Tides and the Tidal Data Analysis 311

19.4.1 Types of Tides 312

19.4.2 Tidal Theories 312

19.4.3 Tidal Data Analysis 313

19.4.4 Applications of Tidal Data Analysis 314

19.5 Dredging 314

19.6 Maintenance of Ports and Harbours 315

19.7 Navigational Aids 316

19.7.1 Short Range Navigational Aids 316

19.7.2 Long Range Navigational Aids 321

Index 332

Appendix 337


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2

Components of a Permanent Way

2.1 Introduction

The structure of a railway track comprising rails fitted on sleepers and resting on ballast and subgrade

is termed a permanent way. It is made up of the following components (Fig. 2.1).

Figure 2.1 Components of a permanent way; the dimensions pertain to single lane BG track

(a) Rails

(b) Sleepers

(c) Fixtures and fastenings

(d) Ballast

(e) Sub-grade

All the above components of the track are extremely important for the safe functioning of the rail-

ways, and care should be taken to install them correctly, using the correct components for each type of


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10 Transportation Engineering

the travel, similar to what the wave motion theory states. The direction and amount of creep dependson the net results of backward and forward forces.

Percussion theory: According to this theory, creep occurs due to the impact of wheel loads at the

rail end at the joints (Fig. 2.7(c)). The repetitive wheel loads on the rail end presses the trailing rail

downwards and the impact of the load is felt on the end of the forward rail. As a result, battering

(bending down) of the rails at joint faces takes place. Such repetitive impact of rolling wheels in the

direction of its movement pushes the forward rail ahead and causes creep. The percussion effect can

be controlled/eliminated by using strong/firm fish bolts, replacing worn out fishplates/spring washers,

tight packing of ballast, narrowing of the wide expansion joints, reducing design speed with reduced

axle loads, particularly on steep downward gradients.

Figure 2.7 Theories on rail creep (schematic)


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Figure 3.5 Variation in wheel loads distribution on rails over curves

3.4.1 Extra Clearance on Curves for High Speed Routes

The Indian Railway Board has issued instructionsto be followed while increasing the speed over curves

of BG tracks (160 km/hr or 200 km/hr). Extra clearances between structures (if there are any) and

the adjacent tracks laid on curves for high speed routes (160 km/hr and 200 km/hr) are separately

prescribed as Annexure I and II of IRSD (2004).

3.4.2 Cant and Related Terminology

The following terminology is used to understand the basic concepts considered for geometric designof railway tracks (IRPWM 2004).

Cant or superelevation: It is the amount by which the outer rail is raised or depressed with reference

to the inner rail of the curved track. A positive cant is defined when the outer rail is raised above the

inner rail; conversely, a negative cant is defined when the inner rail of the curved track is raised above

the outer rail.

The maximum value of cant to be provided on a curved track depends on the drainage levels of

surrounding permanent structures and possible upgradation/increase of speed in the future. The maxi-

mum cant value that should be considered for BG route groups A, B and C is 165 mm and for BG route

groups D and E is 140 mm; for MG: 90100 mm and; for NG (762 mm): 6575mm (IRPWM 2004).

Equilibrium speed: It is the speed of the vehicle by which the centrifugal force developed by the

vehicle over the curved track is exactly balanced by the amount of cant provided. As a result, the pres-

sure distribution on both the rails will be equal (Fig. 3.5(b)). The amount of cant provided to obtain

this maximum speed for the designated curve is termed as equilibrium cant and is calculated by using

Eq. (3.9).

Equilibrium cant =

Gv2

gRc

(3.9)

Cant deficiency: When the speeds of vehicles travelling on the curved track are higher than the

equilibrium speed, the cant provided is not sufficient to balance the pressure distribution on the rails

(Fig. 3.5(a)). The difference between the cant required and the cant provided is called cant deficiency.The following relationship may be used to calculate the cant deficiency.

Cant deficiency=Theoretical required cant Actual cant provided. (3.10)


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Geometric Design of a Railway Track 45

Figure 3.8 A typical combined curve

where R1 and R2 are the radii of curvature at points 1 and 2 respectively. L1 and L2 are the lengths of

the transition curve corresponding to times t1 and t2. However, the above relationships do not satisfy

the given condition at the beginning point (or tangent point) of the transition curve.

Transition curves with spirals are preferred in railway alignments due to the following reasons.

Superelevation on the curved path can be increased at a uniform ratesame as the rate of de-

crease of radius of the transition curve.

Transition curves help to avoid the sudden impact of centrifugal force by providing smooth

change consistent with the vehicles path.

Centrifugal force is reciprocal to the change in alignment curvature. When the speed of the

vehicle is assumed to be constant, non-uniform change in the magnitude of the side pressure

takes place due to abrupt changes in curvature. The differential side pressure (or thrust) has a

detrimental effect on the surface of the rails as well as the vehicle performance. In such alignment

of track with abrupt changes, transition curves should be inserted suitably.

Transition curves facilitate gradual change in turning angle of steering wheels.

They provide safe and comfortable travel on the curve even at high speeds.

Transition curves can be inserted in the alignment of railways between:

(i) Two straight parts of an alignment.

(ii) Circular curves aligned in the same and opposite directions having the same or different radii.

(iii) The alignment of a straight part and a circular curve.

3.4.5 Safe Speed on Horizontal Railway Curves

The safe maximum permissible speed on curves with different categories is determined by using the

following formulas as recommended by the India Railway Board (IRPWM 2004):

Fully transitioned curves

For BG : V =0.27R(Ca + Cd) (3.14)


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3.5 Vertical CurvesVertical curves should be provided at the junction of two grades when the algebraic difference between

the grades 4 mm per metre or 0.4%. The minimum radius of vertical curve provided for a BG rack

is 4000 m for group A, 3000 m for group B, and for other groups, including all routes of MG track, it

is 2500 m (IRPWM 2004).

3.5.1 Types of Vertical Curves

Based on the nature and intensity of the steepness of adjacent grade lines, different types of vertical

curves are formed (Fig. 3.11). They are (i) summit (or crest) curves and (ii) sag (or valley) curves. The

intersection point of adjacent grade lines is termed as the vertical point of intersection (I). When the

elevation (or reduced level, RL) of point I is higher than or equal to any point on the vertical curve, it

is called a summit curve. When elevation of point I is lower than or equal to any point on the vertical

curve, the curve is called a sag curve.

The point of curvature (which is at the curve beginning) and the point of tangency (which is at the

curve end point) are termed asT1 andT2respectively. The positive and negative signs of the gradient

(g%) indicate upward and downward slopes of the ground respectively. G is the angle of deviation of

adjacent grade lines which is equal to the algebraic difference of tangent grades |g2 g1 |and its value

is expressed in decimal form. The above notations are used in Fig. 3.11.

Figure 3.11 Possible cases of forming vertical railway curves based on adjacent grade lines

Details of calculations of a model curve is presented in the Appendix.


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4

Points and Crossings ofRailway Tracks

4.1 Points and Crossing (Turnouts)

Points and crossings are used to help trains transit smoothly from one track to another. The direction of

crossing of these two tracks may be parallel or diverging or converging. As the wheels of the trains aremade with inside flanges, they need to be driven properly at these track junctions. Points, also termed

as switches, are used to divert the vehicle from one track to the other; the gaps between the rails allow

smooth crossing of the flanged wheels from one track to the other. A complete set of track components

including points and crossings with lead rails is called a turnout (Figures 4.1 and 4.2).

Figure 4.1 Basic components of a right-hand turnout (or a switch)


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Figure 4.14 Scissors crossing (Courtesy: South Central Railway)

left-hand spring crossing. The movable wing rail is anchored at the heel of the crossing. The fishplate

fixed at the heel of the movable wing rail is bent to permit free movement of the wing rail.

Mixed gauge turnoutMixed gauge turnouts have a common rail between the tracks and may form such turnouts withdifferent

combinations of rail sections, crossing angles and gauge tracks.

Double turnoutsDouble turnouts (or tandems) are designed sparsely on tracks which are located in congested yards.

As its essential feature, one turnout falls within the lead curve of another turnout. The adequacy of thedistance between the actual toe of the switch of one turnout behind the other depends on the ease of

divergence for the throw of the trailing switch rails. Based on the type of acute angle crossing formed

by the intersection of the gauge lines of the outer rails, these turnouts are formed with contraryflexure

and similar flexure.

4.5 Design of Turnout Components

The turnout may be laid with any one of the following geometry of switches:

(i) Straight switch (Fig. 4.15) (These are most widely in use on Indian Railways),(ii) Partially curved switch (Fig. 4.16) and

(iii) Fully curved switch (Fig. 4.17(a) and (b)).

The fully curved switch may further be laid with any one of the following type of geometry:

Non-intersecting curved switch (Fig. 4.17(a)),

Intersecting curved switch and (Fig. 4.17(b)) and

Tangential curved switch (Fig. 4.17(c)).

Determination of length of lead (L) and radius (R) of turnout are the most important componentsconsidered while designing turnouts. The values ofL and R of the turnout with any one of the above

combinations (Figures 4.154.17) can be calculated by using the formulae recommended by the In-

dian Railway Standard Track Manual. The values of straight length along the rail measured from the


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train is further continuing its journey. Such rule with Intermediate Block Post is also applicable in thiscategory. For example, Class C stations are formed where bock sections are divided into two parts.

Class D stations: These are non-block stations. Class D stations are stopping places which are situated

between two consecutive block stations; they do not form the boundary of any block section. These

stations are used only as halt stations without signals.

5.5 Quadrant Aspect of a Semaphore Signal

The movement of a semaphore arm from position 1 through position 3 is called the upper quadrant

system (UQS) and its movement from position 3 to position 4 is called the lower quadrant system

(LQS) (Fig. 5.7). Two aspect signalling (TAS) is adopted in the lower quadrant (LQ) and multipleaspect signalling (MAS) is adopted in the upper quadrant (UQ). The signals categorised in each case

are briefly explained below.

Figure 5.7 Positioning of semaphore arm in vertical plane

5.5.1 Two Aspect Signalling (TAS)

Warner signalThis signal is used to provide advance information to drivers to overcome the problem of (a) low speed

operation of trains which stop at the stop signal ahead, and as the result, (b) reduction in number of

trains operated per day in a block section. The warner signal only warns, it does not stop the train there.

The combination of red light with thefi

sh-tailed semaphore arm mounted with an additional green lightON, distinguishes the warner signal (Fig. 5.8) from the stop signal (Fig. 5.6(a)). The colour lights of

the warner signal display the intended information to drivers during night time when the semaphore

arm is invisible. When both the green lights are ON (Fig. 5.8(b)), it indicates that the there is no need


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Figure 6.7 Primary forces acting on an airplane in flight

thrust. Bernoullis principle states that a fluid that flows faster over a surface will develop less pressure

on it than a fluid that flows more slowly. Based on this basic principle, the wings of airplanes are

designed as airfoils and maintain less air pressure on its top surface than underneath. This difference

in pressure across the wings-plane generates the lift force.

There are several types of geometric specifications pertaining to airports which depend on the physical

and technical characteristics of different type of aircrafts and their operational conditions. Aircraft

characteristics play a vital role in the geometric design of various components of airports. The follow-

ing are a few details that show the relationship between aircraft characteristics and component parts of

an airport.

Weight of aircraft: It depends on several parameters, conditions such as fuel level, pay load and crew

and operating conditions such as maximum allowable weight of aircraft intended for take-off, landing

and at rest.

Pay load: It is the actual load carried by an aircraft which produce revenue. This includes

weight of passengers, mails, goods/cargo and baggage. Such maximum loads may be consid-

ered as individual or combined and designated as the maximum structural payload (MSPL).

The carrying capacity of commercial airlines may vary between 35 and 800 seats in case of lo-

cal/regional airlines and major airlines, respectively. The MSPL will be less in case of passenger

carrying aircraft than cargo aircrafts since the space occupied by a passenger is more than the

space occupied by cargo/goods. This weight is considered as crucial; and is normally used to

design aircrafts based on the aircrafts purpose of usage. Technological developments in air-

crafts physical design and their operational capabilities have made it necessary to make changes

in the conventional procedure of planning and specifications of pavements, airport airfield and

the terminal areas.

Operating empty weight (OEW): It is the lightest weight of aircraft. It consists of the weight of

its basic body and crew but does not include fuel and pay load.

Maximum gross take-offweight (MGTOW): It is the maximum weight authorised for take-off. It

includes the weight of the (i) basic OEW, (ii) fuel required for trip and reserve and (iii) payload;

the weight of fuel consumed during taxiing and for any ground manoeuvres is excluded.


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Figure 6.11 Component parts of airplane

6.9.2 Length of Aircraft

As the length of the aircraft increases, the distance between the main landing gear and the pilots

eye also increases. This will result in requirement of a larger turn fillet and turn radius and spacing

between adjacent taxiways. As an example, the length of aircrafts may vary between 23 feet 9 inches

for a PA28-Archer (of Piper), a piston and turbo-prop engine aircraft and 239 feet 3 inches in case of

an A-380 (of Airbus) jet aircraft.

6.9.3 Wing Span

This length is designed capable to lift and drag flight loads. In most airplanes, fuel tanks are situated

in the wings. The length including wing span and fuselage dictates the minimum required (i) width

of runway, taxiway and size of parking aprons, (ii) spacing between such adjacent pavements (i.e.,

runwaytaxiway and taxiwaytaxiway), and (iii) turning radius of large aircraft. As an example, the wing

span may vary between 33 feet 6 inches for Eclipse 500 (of Eclipse), a very light jet aircraft and 239

feet 3 inches in case of A-380 (of Airbus) jet aircraft. A study reveals that the width between the outer

to outer spread of the main landing gear may vary between 15 and 27% of the wing span (IIWG 2007).

6.9.4 Wheel Base

As an example, the length of aircrafts may vary between 41 feet 5 inches for A-320-200 (of Airbus), a

narrow body jet aircraft and 99 feet 8 inches in case of A-380 (of Airbus) jet aircraft.

6.9.5 Gear Tread or Wheel Track or Landing Wheel Track or Landing WheelGear

As the fuselage height decreases, the width of the landing gear decreases. The width of the landing gear

is also interdependent on fuselage cross-section (IIWG, 2007). As an example, the length of aircrafts

may vary between 16 feet 8 inches for MD-87 or MD-90-30 (of McDonnell-Douglas), a narrow body

jet aircraft and 46 feet 11 inches in case of A-380 (of Airbus) jet aircraft.

6.9.6 Landing Gear Tread

The landing gear system supports the entire weight of an airplane during ground operations and land-

ing. The wheel system is attached to the primary frame of the airplane and the type of gear system


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by the nose gear offset outward of the centre line of the taxiway curve (Fig. 6.14). The former case ismost generally adopted by pilots and it requires a small fillet but in the latter case, the size offillet/area

requirement will be more because the path traced by the nose gear will be away from the centre line of

the taxiway curve.

6.9.10 Landing Gear Tread versus Gross Weight

The width of the landing gear tread will increase with increase of gross weight. Subsequently, wind

span increases. This increase in width of landing gear tread will dictate the minimum required width

of runway and taxiway, and their fillet radii (IIWG 2007).

6.9.11 Ground Speed or Cruising SpeedIt is the relative velocity of the aircraft with reference to the ground, when the aircraft is operated in air

at its maximum speed (Fig. 6.15).

Figure 6.15 Calculation of ground speed with reference to air speed of aircraft and wind speed

6.9.12 Air SpeedIt is the relative speed of aircraft with respect to the speed of wind.

6.9.13 Jet Blast

High speed jets aeroplanes are prone to eject hot (up to 1300C) exhaust gases at velocity up to 200

km/h. Deflectors are used to dissipate them (Figs 6.16 and 6.17).

6.9.14 Surface Friction of Runway

The runway surface should have minimum frictional resistance to stop a landed aircraft at a minimum

distance. This parameter is considered as a crucial safety measure during wet and snow climates.Runway surface is provided with tinning to obtain a standard range of frictional resistance. The tinned

surface can also eliminate the possibility of occurrence of hydroplaning (loss of steering or brake

control when a layer of water prevents direct contact between the wheels and the runway) during


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Figure 8.6 Example problem: Wind rose diagram-II with additional runway


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10

Geometric Components of theRunway and Taxiway System

10.1 Basic Components of a Runway

The runway system comprises structural pavement of runway and the associated components such as

runway shoulders, blast pad, runway strips, runway thresholds, runway end safety areas, clearway and

stopway. These components are briefly defined and their applicable standards discussed below.

Runway thresholds: These are the markings painted across the width of the runway that denote the

beginning and end of the designated spaces for take-offand landing under specified conditions.

Clearway: It is an obstruction free paved rectangular surface abutting the end of a runway within

which an aeroplane takes offto an initial climb of 35 ft (10.7 m) above the surface at its end (CASA

2012). The length of clearway cannot exceed half the length of the take-offrun available on the runway

(ICAI 2006; CASA 2012).

Stopway: A stopway may be optionally provided at the end of a runway on which an aeroplane may

be stopped in case of an aborted take-off. The width of a stopway must be as wide as the associated

runway width. The minimum length of the stopway must be provided as its other end finishes at least

60 m before the end of the runway strip. The stopway may be provided with an asphalt surface and

surface frictions similar to the associated runway surface friction. The bearing strength of the stopway

pavement should be able to support at least one single pass of the critical aircraft without causing

structural damage to the aircraft. Slope and slope change along the stopway should be the same as that

of its abutting runway but in no case should it exceed 0.8% for thefirst and last quarter of the length of

the runway (CASA 2012).

10.2 Declared Distances Associated with a Runway

(ICAO 2006; CASA 2012)

Declared distances represent operational distances to a pilot for landing, take-off

or safely abortingtake-off. These distances indicate the runway adequacy for different operations of aircrafts. They are a

combination of the runway, clearway if provided and any stopway (Fig. 10.1). Declared distances can

be calculated for each runway direction in the following manner.


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Geometric Components of the Runway and Taxiway System 171

Table 10.8 Minimum standard sight distance on taxiway (CASA 2012; Courtesy of Civil Aviation SafetyAuthority, www.comlaw.gov.au)

Code letter Minimum line of sight

A 150 m from 1.5 m above taxiway

B 200 m from 2 m above taxiway

C, D, E or F 300 m from 3 m above taxiway

10.4 Instrument Landing System (ILS)

An instrument runway is equipped with radio beam facility through which reference, landing can be

made by an instrument landing system (ILS).

The ILS is a standard sequential procedure based method used for navigation of aircrafts on to an

instrumental approach landing runway (Fig. 10.6). It was accepted by the ICAO in 1947. It provides

the horizontal and vertical guidance necessary for accurate landing during limited and reduced visibility

condition by adopting instrument flight rules (IFR). This accurate landing approach is a standardised

procedure. It permits descend of flight on to a runway by using navigation equipments which are

located on the ground in coaxial with the trajectory. It relays instant information about the angle of

descent to the point of touch down. However, the ILS equipment does not provide instant information

to the pilot about the distance to the point of touch down.

Figure 10.6 Basic components of an instrument landing system, ILS (Schematic)


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11

Airport Visual Aids11.1 Introduction

The visual aids used in association with the runway system may be broadly categorised into runaway

markings, taxiway markings, airport signs and the approach lighting system (www.faa.gov.in; Trani

2003).

11.2 Runway Markings

The markings for runways and the landing area of the general heliport are generally white. Red colour

marking is provided on heliports located in hospital premises. There are six basic types of (FAA AC

150/5340-1H; FAA AC 150/5340-18F; www.pilotfriend.com and airlinebrats.com) runway markings.

Runway centre line: The centre line of a runway can be identified by uniformly spaced stripes which

are marked along the centre of the runway (Fig. 11.1). These markings provide guidance to pilots

during landing and take-offoperations.

Runway designation markings: Designation of the runway is marked across its width. This mark-

ing indicates the centre lines magnetic azimuth and includes a symbol applicable in case of parallel

runways, if they exist (Fig. 11.1).

Figure 11.1 Runway markings (A schematic diagram)


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Figure 11.20 Different types of rotating beacons used in airports (Courtesy of Hali-BriteInc. www.halibrite.com)

Aerodrome beacon: A rotating beacon is installed at an airport or aerodrome on an elevated tower to

indicate its location to the pilots from the air, at night. The beacon produces flashes of colour lights at

24 to 45 rpm. Beacon visibility extends up to 64 km (at 400,000 to 190,000 candlepower). Beacons

come in any combination of clear, green, red and amber colour filters to meet required specifications

(Fig. 11.20).

11.5 Approach Lighting System (ALS)

Approach lights provide navigational guidance to the runway in the vertical and lateral plane with

relation to height perception, roll guidance and horizontal reference. The ALS plays a critical role

during the transition from instrumentflight to visual flight for landing. They are very important during

inclement weather and low visibility operations in the airport. In such cases, the approach lights

facilitates continuing the approach to 100 ft above the runway, at which point, the geometry of the

runway can be seen clearly (Fig. 11.21).

Several types of approach lighting systems are available in airports in the US and a few commonly

used systems are listed below (FAA, 2010; www.flightlight.com; www.rainierflightservice.com/blog/can-

i-descend;www.carmanah.com; www.honeywell.com):

High intensity runway lighting system (HIRL):Examples include ALSF I and II, and short ap-

proach lighting system (SALS)/SALSF, high intensity with inner 1500 ft of ALSF I. Medium intensity approach lighting system (MALSR):MALSR with runway alignment indicator

lights is used during instrument landing approach for aligning aircrafts with the centre line of

the runway. The MALSR use up to 63 steady burning lights to create a reference plane and up

to 8 lights to create a sequential strobing flash pattern light that rolls towards the runway thresh-

old. Three intensity settings are used under changing weather conditions. Examples include

MALD/MASLF, MALSF.

The above ALS and their associated lighting system with the runway are briefly described below.

ALSF I and ALSF II: These are single and three intensity lighting systems (Range: 2,400 ft (426.72

m)). Approach lighting system with sequencedfl

ash lights (ALSF) I and II is used for Category I andII runways, respectively. These systems are useful during instrument landing approach (ILA) to align

the aircrafts with the runway centre line and to establish its vertical orientation. Up to 21 white lights

create a sequential strobing flash pattern that rolls towards the threshold end of the runway in use.


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Design of Runway Pavements 209

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Figure 13.7 Equivalent single wheel load (ESWL) by equal stress concept (Based on Boyd and Foster 1950)

The ESWL for a single wheelsingle angle axle assembly (Fig. 13.7) on a flexible pavement can be

calculated from the following formula:

log10ESWL=log10 P +

0.301 log10

z

d/2

log10

2s

d/2

, (13.1)

where,

P = Wheel load Axle load/4,

s = Centre-to-centre spacing between the two wheels= (d+ 2a),

d= Clear distance between the two wheels= (s 2a),

a = Radius of tyre contact area,

z= Desired depth.

The coordinates to plot the relationship between load versus depth of flexible pavement can be

calculated as (d/2,

P) and (2

s, 2P

).In case of ESWL on flexible pavements due to dual tandem assembly, the coordinates can be cal-

culated as (d/2,P) and (2R, 4P), where R is the diagonal distance between the two wheels (Fig. 13.8).


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14

ACN

PCN System of RatingAerodrome Pavements

14.1 Introduction (ICAO 1989)

In 1981, the ICAO promulgated the ACNPCN method as the single universal system of rating aero-

drome pavements. This method determines the weight limitation of aircrafts operating on the pave-

ments by comparing the PCN (pavement classification number) with an ACN (aircraft classification

number). The ACNPCN system provides a universal standard of rating airplane/pavement compati-bility, replacing several such rating systems, including the load classification number (LCN).1

The ICAO Annex 14 of Volume 1 specifies that the bearing strength of an aerodrome pavement

which is intended to be used for aircrafts having mass (i.e., maximum takeoffweight, MTOW) greater

than 5700 kg should be rated based on the aircraft classification numberpavement classification num-

ber (ACNPCN) method (ICAO 1989). The ACNPCN method as specified by the ICAO (1989) is

explained in this chapter.

ACN: It is a number representing the relative damaging effect of an aircraft on a pavement for a spec-

ified standard sub-grade strength.

PCN: It is a number representing the bearing strength of a pavement for unrestricted operations by

aircraft, with ACN value the PCN. In other words, if the ACN PCN, the pavement can support theaircraft without weight restrictions.

The ACNPCN method of expressing standard format of numbering is presented in Fig. 14.1.

1* Load classification number (LCN): It is a system of classification of aerodrome pavements based on their supporting

capacity. It indicates the pavements ability to support loads due to ground operation of aircrafts without causing any cracking

or distresses. Plate load tests are conducted on the pavement and the ESWL of any aircraft is derived. The obtained number is

expressed as a single numberthe LCN. The ESWL concept has been briefly explained in Section 13.3.2. The factors affecting

LCN are listed as gear geometry, tyre pressure, composition and individual layer thicknesses of the pavement. If the LCN of the

runway pavement >LCN of an aircraft, the aircraft can be safely operated on that pavement, else its operation is restricted on

that runway pavement.

The LCN system was developed by ICAO in 1965. It does not discriminate between flexible and rigid pavements. The LCN

system of rating strength of runway pavements has become obsolete now, as theflexible and rigid pavements behave differently

under loading.


30/34


Figure 15.6 Typical inlet grates

Suitability of different types of inlets Grate inlets effectively intercept water flowing in the gutter channel but there is a chance of

clogging due to debris.

Curb inlets are relatively free from clogging due to debris. They are preferred where (i) grates

placed in traffic lanes would cause reduction in the effective width of the lane and (ii) grates

would pose problems related to safety of pedestrians and cyclists.

Slotted drain pipe inlets are suitable along curved lengths adjacent to curbed or uncurbed sec-

tions. They offer little interference to traffic operation compared to grates. The clogging problem

remains the same as with grates.

Combination inlets and depressed combination inlets are more superior to the individual inlets.

Such inlets have greater interception capacity and avoid ponding of water on traffic lanes due to

clogged grates. Depressed inlets are suitable on sloped length of sag curves.

Bell mouth shaped inlets are more suitable where there is no longitudinal gradient available. In

such cases, curb channels on either side are kept inclined and the run-offwater is allowed to

enter into an RCC pipe of diameter 300 mm placed across the footpath at an interval of 10 to15 m or any other suitable interval dictated by nearby airport roads alignment. The intercepted

water is ultimately discharged into a roadside channel drain.

Inlet grates should be installed 2 to 3 cm above the lowest places on valley curves so that infil-

tration of silt can be averted.

15.3.4 Design of Curb Channel or Gutter Channel

The maximum depth offlow (d), spread of water on the pavement (Ts) and location of inlet grates along

the gutter channel, with sufficient infiltration capacity are usual criteria for deciding design adequacy of

gutter channels having any cross-section (Fig. 15.7). Provision for maximum allowable values ofdandTsare termed aspavement encroachment criteria. To determine the above parameters, rate offlow (i.e.,

discharge) in the gutter channel is essential and depends on the intensity of rainfall during the design

life, longitudinal gradient and surface characteristics of the catchment area. The design inflow into


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17

Maintenance of Airport Pavements17.1 Introduction

Airport pavement maintenance works are managed systematically for (a) assessing current condition

of pavements, (b) determining maintenance and rehabilitation needs and (c) prioritisation of the main-

tenance works of candidate pavements with reference to funding levels. For all these purposes, it is

essential to evaluate the airport pavements in terms of their distress or by any appropriate parameters

related to performance (WSDOT).

Airport pavement maintenance activities are briefly discussed in the following sections.

17.2 Maintenance and Rehabilitation of Airfield Pavements

17.2.1 Interpretation of a Condition Rating

The condition rating provides a rational basis for ranking the maintenance of member pavement sec-

tions considered according to their current condition index values with reference to its performance

curve (Fig. 17.1). In this process, the PCI (pavement condition index) can be used in the PMS (pave-

ment maintenance system) to provide a benchmark for comparing the relative condition of a group of

pavements in a road network. The PCI is primarily used to support pavement management initiatives

of federal, state and local government agencies. This will facilitate avoiding ambiguous conditionsparticularly during paucity of funding. Programming and long-term budgeting can be possible, with

reference to the list of such rankings. In addition, the index value assigned by the condition rating

provides an appropriate method of repair with suitable construction technology.

The condition index related with the condition rating provides a preliminary basic indication of the

type of repair work needed, suitable time and extent of maintenance (Fig. 17.1). Subsequently, long-

term and short-term maintenance activities with their schedule can be worked out under the frame work

of budgetary allocation and available resources. Ultimately, the condition rating concept can be used

to evolve innovative approaches to tackle complex combinations of maintenance needs for pavements

under distress conditions influenced by inconsistent parameters related to traffic, weather, drainage,

material characteristics and construction quality. The trend of performance curve which depends onthe rate of deterioration due to these factors will decide the timely management of several activities

specifically for cost effective maintenance. As a whole, the above concept of pavement maintenance

with reference to measured performance over a period of time is termed as PMS.


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18

Planning and Layout of Docksand Harbours

18.1 Introduction

In this chapter, we will discuss a few details and the required terminology which are essential for

understanding marine transportation and the maritime structures/components (AAPA).

18.2 HarboursA harbour or haven is a place on a coast where vessels (such as ships, large boats and large barges) may

find shelter, particularly against stormy weather, wind and high tides. The artificial structures which

offer such protection in harbours include piers, jetties or sea walls, and breakwaters.

18.2.1 Harbour planning principles

The following planning principles provide guidelines for related individuals and organisations to fa-

cilitate the sustainable planning, development, management and enhancement of harbour and harbour

front areas.

(a) The site selected should be safe from strong wings, strong waves; the shore must be strongenough to accommodate all required equipment installations at low principal and maintenance

costs.

(b) The main harbour components such as ports, docks, container stores, truck terminals and the

equipment associated with harbour activities should be situated accordingly so that their activi-

ties are not hindered due to their misplacement.

(c) The master plan of a harbour should accommodate all possible future needs of the forecasted

demand, specifically with reference to individual needs.

(d) The harbour must be protected and preserved for the use of economic and social purposes that

enhance the living standards of the people at the local and regional level.

(e) It should group tourism attractions in clusters while balancing the needs of other uses.

(f) Hinderland areas nearby should be integrated with the public waterfront through improved visual

landscape, cycle tracks and truck lanes.


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19

Construction and Maintenance of

Docks and Harbours

19.1 Introduction

In this chapter, we discuss construction of different component structures of docks and harbours. Their

maintenance activities are also explained.

The harbour structures explained below, each have their particular merits for a given set of condi-

tions and each require to be considered carefully within the evaluation process (Maine 1997).

19.2 Construction of Quay Walls

Quay walls are earth retaining structures which are used as berths for docking floating vessels and

transfer of goods. They also function as pathways between the transit shed/warehouse and structures

built offshore.

Quay walls are of various types. They are used for anchoring during halting (i.e., mooring purpose)

and berthing of any type of water vehicle such as ships, vessels, boats or barges. Quays are equipped

with different types of anchoring installations such as bollards (which are fixed on its floor and used

for anchoring ships), fenders (which are fixed on its vertical face and again used for anchoring ships),

cranes (which are used for lifting weights) and other equipment moving along the ship.The following types of quay walls can be built in a harbour/port based on the type of compo-

nents/materials used and the site condition.

Gravity or solid block quay walls: These are early conventional types of quays and their self weight is

designed as the water pressure retaining structure. The basic principle behind the design of the gravity

wall is to provide the structure such a heavy weight that its resultant weight and the other static and

dynamic forces acting on it disallow slide out or rotate or slip. These walls are suitable in areas where

the load bearing soil bed is strong enough to withstand the vertical loads. The durability of the walls

depends on the type of solid blocks used to build the quay wall. Conventionally, stone blocks were

used. In recent constructions, heavy weight concrete blocks have also been used.

Sheet piled quay walls: The sheet pile wall is a vertical beam which is loaded by water pressure and

soil pressure on either side. Sheet piled quays are suitable at coast lines with weak soil. The fixation

capacity of the piles in loose soil determines the stability of the quay during its operation and against


34/34

www.universitiespress.comCover design:OSDATA, Hyderabad

9 788173 719240

ISBN 978 81 7371 924 0

ENGINEERING & TECHNOLOGY

In a first coursein transportation engineering at the undergraduate level,the various aspects of road

transportation, particularly highway engineering, are generally covered in detail.This book extends

the discussion to other critical components of the transportation system, namely railways, airways

and waterways, by emphasizing the basic infrastructural components, principles of planning,

functional design, operation and management of the infrastructure in each case. It dwells on thelatest approaches/methodologies in the design and evaluation of railways, airports and docks &

harbours, andincludes a large numberof illustrations, images andworked-out examplesto enhance

the understanding of thedesignelementsand components of the system ina practicalway.

Salient features of the book

Railways:

Airports:

Docks&Harbours:

Details of Indian Railway routes; features of permanent way components; geometric design of

railway tracks; functional aspects of points and crossings with solved examples on design of turnout

components; signals used in Indian Railways, their aspect form; working principle of axle counter and

track circuit; particulars of automatic signalling system; types of interlocking systems and their merits

anddemerits

Airport master plan and runway orientation; aircraft characteristics, design and orientation of

runways using Wind Rose diagrams; FAA design standard for minimum wind coverage; classification of

airports and estimation of design runway length (FAA and ICAO standards); standards for geometric

components of runwayand taxiway systemas perFAA,ICAI andCASA;descriptionof instrument landing

system (ILS), approach lighting system, VASI, precision approach path indicator lighting system and

visual aids; air traffic control (ATC) with the terminal component facilities; design of runway pavements

based on UFC, FAA, PCA, US Army and Air Force systems; ACN-PCN system of rating aerodrome

pavements;airportpavementdrainagesystem,failures-evaluationandthemaintenanceaspects.

Planning,layout,constructionandmaintenanceofdocksandharbours.

is a faculty member in theDepartment ofCivil Engineering,UniversityCollege of

Engineering, Osmania University, Hyderabad. He has a BE degree in civil engineering and ME and

PhD degrees in transportation engineering. He was awarded the Indian Roads Congress

Commendation Certificate for the best research paper published in the IRCJournal (20012002). He

has worked as a member of theStateTechnicalAuthority (STA) for the Pradhan MantriGram Sadak

Yojana (PMGSY), Rural Roads Project. He is the author of (2011),

(2013) and (2014)

publishedbyUniversitiesPress.

RSrinivasaKumar

Textbook of Highway Engineering

Pavement Design Pavement Evaluation and Maintenance Management System

Transportation Sample Chapter

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