ce 323-highway engineering

YEAR III, SEMESTER II

LECTURE NOTES

Researched and Compiled by

Okello Francis Eugene

February 2010

FACULTY OF ENGINEERING Department of Civil and Building Engineering

Kyambogo University | P. O. Box 1, Kyambogo Uganda CE323 Highway Engineering 1, Lecture Notes. FOE- 2010. E-mail: [email protected]. Mobile No.: (256) 701 806514 i

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Course Structure Third Year; Semester II

Core Course: Yes

Lecture Hours [L]: 45 Contact Hours [CH]: 60

Practical Hours [P]: 30 Credit Units [CU]: 4

Class Hours Day Evening

Monday: 1400 1600 hrs 1700 1900 hrs

Course Assessment

Course Work: 40% [Assignments 15%, Tests 25%]

Final Examination: 60%

Normal Progress

Grade Point [GP] 2.0 [50%]

Course Outline Introduction: History and Development of

roads;

Planning and Layout of Roads; Route Surveys; Selection of Routes; Site Investigation; Soil Survey; Types of Roads: Low Cost Roads, Granite

Sets, Flexible & Rigid roads;

Soils Technology for Roads; Soil Stabilisation; Construction Techniques; Drainage; Street Lighting; Highways; Rural roads;

Urban Roads; Single and Double Carriageways; Junctions; Intersections; Roundabouts; Road Furniture; A Case Study of Uganda; Maintenance of Roads.

Field Exercise:

Planning of one Layout of Length of a New

Road Using Available Contoured Maps

Kyambogo University | P. O. Box 1, Kyambogo Uganda CE323 Highway Engineering 1, Lecture Notes. FOE- 2010. E-mail: [email protected]. Mobile No.: (256) 701 806514

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Table of Contents Table of Contents ................................................................................................................................. iiList of Tables ...................................................................................................................................... viList of Figures .................................................................................................................................... viiSymbols and Abbreviations .............................................................................................................. viii1.0 History and Development of Roads ......................................................................................... 11.0 Introduction .............................................................................................................................. 11.1 Definitions of some common terms ......................................................................................... 11.2 Early Age Road Development ................................................................................................. 11.3 Middle Age Road Development .............................................................................................. 21.4 19th Century Roads ................................................................................................................... 41.5 Roads in the World Today ....................................................................................................... 41.5.1 References ................................................................................................................................ 62.0 Planning and Layout of Roads ................................................................................................. 72.1 Introduction .............................................................................................................................. 72.2 Goals and Objectives ............................................................................................................... 72.3 The Project Cycle ..................................................................................................................... 82.3.1 Components of the Project Cycle............................................................................................. 82.3.2 Problem Identification.............................................................................................................. 82.3.3 Pre-feasibility ........................................................................................................................... 92.3.4 Feasibility ................................................................................................................................. 92.3.5 Design ...................................................................................................................................... 92.3.6 Commitment and negotiation ................................................................................................... 92.3.7 Implementation ...................................................................................................................... 102.3.8 Operation ................................................................................................................................ 102.3.9 Monitoring and Evaluation .................................................................................................... 102.4 Overview of Road Appraisal in Developing Countries ......................................................... 102.4.1 Define Objectives ................................................................................................................... 112.4.2 Determining alternative ways of meeting Objectives ............................................................ 112.4.3 Preliminary considerations ..................................................................................................... 122.4.4 Assess Traffic Demand .......................................................................................................... 122.4.5 Design and Cost different Options ......................................................................................... 122.4.6 Determine Benefits of each Alternative ................................................................................. 132.4.7 Economic Analysis and comparison of alternatives .............................................................. 132.4.8 Recommendations .................................................................................................................. 132.5 A Typical Road Project Appraisal Process in Uganda .......................................................... 132.6 Economic Evaluation of Highway Projects ........................................................................... 162.6.1 Role of Economic Evaluation ................................................................................................ 162.6.2 Some Basic Principles ............................................................................................................ 162.6.3 Time Value for Money ........................................................................................................... 172.6.4 Costs and Benefits .................................................................................................................. 172.6.5 Evaluation Techniques ........................................................................................................... 20


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2.6.6 Comparison of the Various Methods of Economic Evaluation ............................................. 222.6.7 Selection of the Discount Rate ............................................................................................... 222.7 Selection of Routes ................................................................................................................ 252.7.1 Introduction ............................................................................................................................ 252.7.2 Overview of the Location Process ......................................................................................... 262.7.3 Location Surveys in Non-Built-Up Areas .............................................................................. 262.7.4 Road Location in Built up Areas............................................................................................ 282.7.5 References .............................................................................................................................. 293.0 The Road User and the Vehicle ............................................................................................. 303.1 Introduction ............................................................................................................................ 303.2 Human Factors Governing Road User Behaviour ................................................................. 303.2.1 Human Body as a complex System........................................................................................ 303.2.2 Vision ..................................................................................................................................... 303.2.3 Hearing ................................................................................................................................... 303.2.4 Perception, Intellection, Emotion and Volition ..................................................................... 313.3 Pedestrian Characteristics ...................................................................................................... 313.3.1 Speed ...................................................................................................................................... 313.3.2 Space Occupied by Pedestrians .............................................................................................. 313.4 Vehicle Characteristics .......................................................................................................... 313.5 References .............................................................................................................................. 324.0 Geometric Design of Highways ............................................................................................. 334.1 Introduction ............................................................................................................................ 334.2 Highway Design Standards in Uganda .................................................................................. 344.3 Division of Roads into Functional Class................................................................................ 344.4 Design Controls and Criteria ................................................................................................. 344.4.1 General ................................................................................................................................... 344.4.2 Topography ............................................................................................................................ 354.4.3 Traffic..................................................................................................................................... 354.4.4 Design Vehicle Dimensions ................................................................................................... 37a) Design Vehicles ..................................................................................................................... 37b) Dimensions of Design Vehicles ............................................................................................. 37c) Selection of the Design Vehicle ............................................................................................. 384.4.5 Design Speed.......................................................................................................................... 384.4.6 Control of Access ................................................................................................................... 384.5 Sight Distance ........................................................................................................................ 394.5.1 General ................................................................................................................................... 394.5.2 Stopping Sight distance, SSD ................................................................................................ 404.5.3 Full Overtaking Sight Distance, FOSD.................................................................................. 424.5.4 Sight Distance for Multi-Lane Roads .................................................................................... 434.5.5 Set-back Distance at Obstructions of Horizontal Curves ....................................................... 434.6 Horizontal Alignment ............................................................................................................ 464.6.1 Basic Formula for Movement of Vehicles on Curves ............................................................ 464.6.2 Value of the Coefficient of Lateral Friction, ...................................................................... 48


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4.6.3 Maximum super-elevation Value, emax .................................................................................. 484.6.4 Super-elevation Rates ............................................................................................................ 484.6.5 Radii of curves for which no super-elevation is required ...................................................... 494.6.6 Method of Attainment of Super-elevation ............................................................................. 494.6.7 Transition Curves ................................................................................................................... 524.6.8 Curve Widening ..................................................................................................................... 544.6.9 General Controls for Horizontal Alignment .......................................................................... 574.7 Vertical Alignment ................................................................................................................. 584.7.1 Major Requirements of Vertical Curves ................................................................................ 584.7.2 Gradients ................................................................................................................................ 584.7.3 Climbing Lanes ...................................................................................................................... 594.7.4 Cross falls ............................................................................................................................... 594.7.5 Vertical Curves ...................................................................................................................... 604.7.6 Vertical Crest Curve Design and Sight Distance Requirements ............................................ 634.7.7 Vertical Sag Curve Design and Sight Distance Requirements .............................................. 644.7.8 General Controls for Vertical Curve Alignment .................................................................... 664.8 Cross-Sectional Elements ...................................................................................................... 704.8.1 General ................................................................................................................................... 704.8.2 Road Reserve ......................................................................................................................... 714.8.3 Carriageway Width ................................................................................................................ 714.8.4 Central Reservation (Median) Strip ....................................................................................... 714.8.5 Shoulders ................................................................................................................................ 724.8.6 Laybys and bus bays .............................................................................................................. 724.8.7 Kerbs ...................................................................................................................................... 724.8.8 Camber ................................................................................................................................... 734.8.9 Side slope ............................................................................................................................... 734.9 Intersection Design and Capacity .......................................................................................... 734.9.1 General ................................................................................................................................... 734.9.2 At-grade and Grade Separated Junctions ............................................................................... 744.9.3 Basic Forms of At-grade Intersections................................................................................... 744.9.4 Overview of the Design Process ............................................................................................ 754.9.5 At-grade Intersection Types (from a design perspective) ...................................................... 754.9.6 Capacity of a T-Junction ........................................................................................................ 834.9.7 Design Reference Flow (DRF) .............................................................................................. 854.9.8 Delay ...................................................................................................................................... 854.9.9 Rotary Intersections (Roundabouts)....................................................................................... 874.10 References .............................................................................................................................. 935.0 Design of Flexible Pavements................................................................................................ 945.1 Introduction ............................................................................................................................ 945.2 Types of Pavements ............................................................................................................... 945.2.1 Flexible Pavements ................................................................................................................ 945.2.2 Rigid Pavements .................................................................................................................... 955.3 Elements of a Flexible Pavement and their significance ....................................................... 95


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5.3.1 Surfacing ................................................................................................................................ 955.3.2 Roadbase ................................................................................................................................ 955.3.3 Subbase .................................................................................................................................. 965.3.4 Capping Layer (Selected or Improved Subgrade) .................................................................. 965.3.5 Subgrade................................................................................................................................. 965.4 The Pavement Design Process ............................................................................................... 965.4.1 Traffic Assessment ................................................................................................................. 975.4.2 Subgrade Assessment ............................................................................................................. 975.4.3 Material Selection .................................................................................................................. 975.5 Approaches to Design ............................................................................................................ 975.6 Highway Design Standards .................................................................................................... 985.6.1 Uganda Road Design Manual ................................................................................................ 995.6.2 Kenya Road Design Manual .................................................................................................. 995.6.3 TRL Road Note 31 ................................................................................................................. 995.7 The AASHTO Approach to Pavement Design ...................................................................... 995.7.1 The AASHTO Design Equation ............................................................................................ 995.7.2 Regional Adjustment............................................................................................................ 1005.7.3 Design Tables ....................................................................................................................... 1005.7.4 Steps involved in the AASHTO method of Design ............................................................. 1025.8 References ............................................................................................................................ 107


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vi List of Tables

List of Tables

Table 1.1: International Comparison of Road Statistics ...................................................................... 5Table 1.2: Car Ownership Rates (Cars per 1000 persons) ................................................................... 6Table 2.1: Computation of NPV, B/C Ratio and IRR ........................................................................ 23Table 4.1: Terrain Classification ........................................................................................................ 35Table 4.2: Conversion Factor of Vehicle into Passenger Car ............................................................ 36Table 4.3: Dimensions of Design Vehicles ........................................................................................ 37Table 4.4: Level of Access Control ................................................................................................... 39Table 4.5: Stopping Sight Distance on Level Ground for Wet Pavement Condition ........................ 41Table 4.6: Coefficient of Lateral Friction as Recommended by AASHTO ....................................... 48Table 4.7: Maximum Grades as recommended by MoWH&C ......................................................... 58Table 4.8: Minimum Radii for Crest Curves as Recommended by MoWH&C ................................ 63Table 4.9: Minimum Radii for Sag Curves as recommended by MoWH&C .................................... 63Table 4.10: Types of At-grade Intersections as recommended by MoWH&C .................................. 76Table 4.11: The Limits of the Parameters used in Roundabout Capacity Equation .......................... 89Table 5.1: Subgrade Classes ............................................................................................................ 100Table 5.2: Traffic Groups................................................................................................................. 101Table 5.3: Average Vehicle Equivalence Factors, Ci ...................................................................... 101Table 5.4: Traffic Classes ................................................................................................................ 101Table 5.5: Determination of DSN for different Subgrade and Traffic Classes ................................ 101Table 5.6: Layer Coefficients........................................................................................................... 102Table 5.7: Compacted Thickness Ranges ........................................................................................ 102


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vii List of Figures

List of Figures

Figure 1.1: Cross Section of Early Roads ............................................................................................ 4Figure 2.1: Typical Road Project Appraisal in Uganda ..................................................................... 14Figure 4.1: Stopping and Passing Sight Distances on a crest curve .................................................. 43Figure 4.2: Sight Distance Requirements on a horizontal curve with S L ...................................... 44Figure 4.3: Sight Distance Requirements on a horizontal curve with S > L ...................................... 45Figure 4.4: Forces acting on a vehicle on a horizontal curve ............................................................ 46Figure 4.5: Stages involved in attainment of super-elevation ............................................................ 50Figure 4.6: Attaining Super-elevation by revolving about the centre line ......................................... 51Figure 4.7: Main Elements of a Circular Curve Provided with Transitions ...................................... 52Figure 4.8: Widening on Curves ........................................................................................................ 54Figure 4.9: Climbing Lane outside the ordinary lane ........................................................................ 59Figure 4.10: Highway Cross falls ...................................................................................................... 59Figure 4.11: Typical Vertical Curves ................................................................................................. 60Figure 4.12: A Simple Symmetrical Parabolic curve ........................................................................ 60Figure 4.13: Sight distance over crest curves when a) S L and b) when S > L .............................. 62Figure 4.14: Single Carriageway Cross-section Elements ................................................................. 70Figure 4.15: Dual Carriageway Cross-section Elements ................................................................... 71Figure 4.16: Basic Intersection Forms ............................................................................................... 75Figure 4.17: Typical Access Layout showing Visibility Requirements ............................................ 76Figure 4.18: Typical T-Intersections .................................................................................................. 77Figure 4.19: Typical Designs for Control Intersections ..................................................................... 78Figure 4.20: Selection of Intersection Category based on Safety ...................................................... 80Figure 4.21: Selection of Intersection Category based on Capacity .................................................. 81Figure 4.22: Selection of Priority Intersection type based on Safety................................................. 82Figure 4.23: Selection of Control Intersection Type.......................................................................... 83Figure 4.24: Selection of Control Intersection Type.......................................................................... 84Figure 5.1: Definition of Pavement layers ......................................................................................... 95Figure 5.2: Summary of the Pavement Design Process ..................................................................... 98


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viii Symbols and Abbreviations

Symbols and Abbreviations

AADT Annual Average Daily Traffic

AASHTO American Association of State Highways and Transportation Officials

ADT Number of average daily traffic

ALD Average Least Dimension

CBR California Bearing Ratio

E.S.A Equivalent Standard Axle

GB3 Granular Base-material type 3

GIS Graphical Information Systems

HW Allowable Headwater depth

KUTIP Kampala Urban Transportation plan

LL Liquid Limit

LS Linear Shrinkage

M.S.A Millions of equivalent standard axle

MC Moisture Content

MDD Maximum Dry Density

OMC Optimum Moisture Content

ORN Overseas Road Note

PI Plasticity Index

PL Plastic Limit

TRRL Transport Road Research Laboratory


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1 History and Development of Roads

1.0 History and Development of Roads

1.0 Introduction Everybody travels, whether it is to work, play, shop, do business, or simply visit people. All foodstuffs and raw materials must be carried from their place of origin to their place consumption [OFlaherty, 2002]. Historically, people have travelled and goods have been moved by:

a) Road i.e. using cars, wagons, cycles and motor vehicles; b) Water i.e. using ships and boats; c) Rail i.e. initially using animals and then the steam oil or electric powered

locomotives to pull passenger carriages and goods wagons; d) Air i.e. using airships and aeroplanes (20th Century)

1.1 Definitions of some common terms Some terms like highways, roads and streets have precise meanings, though they are often used loosely in practice. A highway is an arterial road facility designed for high speed and high volume traffic in non-urban areas. For example, the national road network of a country is called the National Highway Network. A road is a lower order facility, designed for relatively lower speed and lower volume traffic in the non-urban areas. For example, they can be district roads or village roads. A street is an urban road facility. An Expressway or Express Highway is a superior type of highway facility with full or partial control of access. It is generally consists of divided carriageway that caters for very high speeds.

1.2 Early Age Road Development The origin of roads dates back to the period before the advent of recorded history. While the birth of the road is lost in the mist of antiquity, there is no doubt but that the trails deliberately chosen by early man and his pack animals to facilitate his movements were the forerunners of todays road. As civilization developed and peoples desire for communication increased, the early trails became pathways and the pathways evolved into recognized travelways. Many of these early travel ways-termed ridge ways- were located high on hillsides where the underbrush was less dense and walking was easier; they were also above soft ground in wet valleys and avoided unsafe wooded areas. As civilization advanced, the growth of agriculture took place and human settlements began to be formed. The invention of the wheel in 5000BC and the domestication of animals saw the advent of chariots and carts. These carts enabled heavy loads to be carried more easily


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2 Middle Age Road Development

and gave rise to wider travelways with firmer surfacings capable of carrying concentrated loads, but with less steep connecting routes down to/up from valleys and fordable streams. Thus trackways evolved along the contours of lower slopes e.g. they were sufficiently above the bottoms of valleys to ensure good drainage but low enough to obviate unnecessary climbing. The trackways eventually become well established trade routes along which settlements developed and these gave rise to hamlets and villages - Some of which, eventually, became towns and cities. Early manufactured roads were stone-paved streets of Ur in the Middle East (4000BC), the corduroy log paths near Glastonbury, England (3300BC), and brick pavings in India (3000BC): The oldest existing wooden pathway in Europe, the 2km long Sweet Track, was built across (and parts subsequently preserved in) marshy ground near Glastonbury. The oldest existing stone road in Europe was built in Crete in 2000BC.

1.3 Middle Age Road Development Notwithstanding the many examples of early man-made roads that are found in various parts of the world, it is the Romans who must be given credit for being the first professional road-makers. At its peak the Roman road system, which was based on 29 major roads radiating from Rome to the outermost fringed of the empire, totalled 52,964 Roman miles (approx. 78,000km) in length. Started in 312BC, the roads were built with conscripted or forced labour; their purpose was to hold together the 113 provinces of the empire by aiding imperial administration, extension of the territorial limits of the empire and quelling rebellions after a region was conquered. The roads were commonly constructed at least 4.25m wide to enable two chariots to pass with ease and legions (large group of soldiers) to march abreast. It was common practice to reduce gradients by cutting tunnels, and one such tunnel on the Via Appia was 0.75km long. Most of the Roman roads well built on embankments 1m to 2m high so as to give the troops a commanding view of the country side and make them less vulnerable to surprise attacks; this had the engineering by-product of helping to keep the carriage way dry. The roads mainly comprised of straight sections as they provided the most direct routes to the administrative areas; however deviations from the straight line were tolerated in hilly regions or if suitable established track ways were available. The withdrawal of the legions from Britain in AD 407; foreshadowed the breakdown of the only road system in Europe until the advent of the 17th century. While the Roman roads in Britain continued to be the main highways of internal communications for a very long time; they inevitably began to decay and disintegrate under the actions of weather, traffic and human resourcefulness. Eventually, their condition became so appalling that when sections became impassable, they were simply abandoned and new tracks created about them. The onset of the 18th century also saw foreign trade become more important to Great Britains steadily developing manufacturing industries and soon long trains of carts and


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3 Middle Age Road Development

wagons were common sights as they laboriously dragged coal from mines to iron works, glassworks and potteries and manufactured goods to harbours and ports, along very inadequate ways. Confronted by the above pressures and the terrible state of the roads, parliament passed in 1706, the first of many statutes that eventually created over 1,100 Turnpike Trusts. These trusts which administered some 36,800km of road were each empowered to construct and maintain a specified road length and levy tolls upon certain types of traffic. The development of the toll road system, especially in the century following 1750, was important for many reasons, not least of which were:

a) It promoted the development of road making techniques in Britain and allowed the emergence of skilled road makers e.g. Thomas Telford, John Loudon Mc Adam and Pierre Tresaguet.

b) It established that road users should pay some road costs. c) It determined the framework of the 20th century pre-motorway trunk road network

The steam-powered railway service in 1825 marked the beginning of the end for the Turnpike Trusts as the transfer of long distance passengers from road to rail was almost instantaneous and towns were accessed by railway. Pierre Tresaguet, the inspector general of roads in France was the first to recognize the importance of drainage of roads and its methodical maintenance. He appreciated the role of moisture in soils and pavements and how moisture affects the performance of road beds. Camber began to be introduced in roads during his time. Thus, he can be rightly called the father of modern highway engineering. The name of John Metcalf is associated in Britain with the art of building good and stable roads in the latter part of the 18th century. He used boulders to achieve strong foundations for roads and spread gravel as a surface layer. He pioneered the construction of good roads on soft ground, using a sub base of bundles of heather (Low spreading bush with small pink-purple flowers). Thomas Telford (1757-1834) is yet another illustrious name in highway engineering, immortalized by naming the hand-packed boulder foundation of roads as Telford base. The construction technique held the sway for nearly 150years since Telford introduced it in the early part of the 19th century. A run of names of eminent highway engineers is incomplete without John McAdams (1756-1836). He was a Scottish road builder who has influenced road construction so profoundly that the term Macadam is frequently used in pavement specifications even to this day. His two important principles of good road construction were;

a) It is the native soil that supports the traffic load ultimately and when the soil is maintained in a dry state, it can carry heavy loads without settlement.

b) Stones which are broken to small angular pieces and compacted can interlock each other and form a hard surface.

Thus Mc Adams specifications were at variance with Telfords in that smaller pieces of stones with angular faces were favoured than larger hand packed boulders. He is reported to have given a practical hint to engineers in selecting the size of stones; the size is good if the


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stone can be put into the mouth. How valid his advice is even to this day! Other than the innovative specifications he introduced, Mc Adam is also remembered for his foresight in urging the creation of a central highway authority to advise and monitor all matters relating to roads in Britain. His recommendation is valid even now in Uganda [Kadiyali, 2006].

1.4 19th Century Roads A significant development which revolutionized road construction during the 19th century was the steam road roller introduced by Eveling and Barford. The development of Portland cement in the first decades of the 19th century by Aspin and Johnson facilitated modern bridge construction and use of concrete as a pavement material. Tars and asphalts began to be used in road construction in the 1830s, though it was the pneumatic tyre vehicle which gave a real push to extensive use of bituminous specifications. The automobile had its slow development in the 19th century, but the First World War, 1914-18, gave momentum to its growth. Thus the road was given a new lease of life [OFlaherty, 2002].

(a) Roman Roads (b) British Roads

(c) French Roads

Figure 1.1: Cross Section of Early Roads Source: Mathew & Rao (2007)

1.5 Roads in the World Today Roads are the principal arteries of traffic in the present-day world. The right indicator of a countrys prosperity is its road length and vehicle ownership. Table 1.1 gives an international comparison of road length in some selected countries. The following inferences can be drawn:

a) America has the largest network of roads (6.3million km) b) India, with its 3.3million km of network comes second. c) The density of roads (km/sq-km) is very high in countries like Germany and Japan

which are small in area.


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5 Roads in the World Today

d) In countries which are large in area, the density is low. India has a density of 1km/sq km, USA 0.67km/sq km and China 0.12km/sq km.

e) The percentage of roads paved is very high in countries like UK (100 per cent), Germany (99 per cent) and USA (91 per cent). Nearly the entire length is paved.

f) In India, the percentage of paved roads is 50. In USA, the percentage is 91.

Table 1.1: International Comparison of Road Statistics s/n Counrty Road length (km) Road density (km/sq-km) Per cent paved1 USA 6,300,000 0.67 912 INDIA 2,009,600 0.63 503 BRAZIL 1,939,000 0.23 94 CHINA 1,157,000 0.12 905 JAPAN 1,136,347 3.77 736 GERMANY 650,700 5.97 997 INDONESIA 372,414 0.19 478 U.K. 366,999 1.5 1009 MALAYSIA 93,975 0.29 7510 THAILAND 62,000 0.12 9711 NIGERIA 32,810 0.04 83

Source: Kadiyali, 2006 NB: All values are for 1998 Indias road length now is 3.3million km and the road is 1km/sq km.

In modern times, Europe saw the beginnings of the Expressway system of World War II. Italy, under Mussolini, started the Autostrade. The famous German Autobahns were planned in the late 1920s and Hitler accelerated their completion. The Autobahns became a key part of the war-time infrastructure for the movement of tanks and other military vehicles UK started its Motorway construction rather late, in the 1950s. These form the arterial road grid of the country linking London to major cities like Manchester, Liverpool, Hull, Bristol, Edinburgh and Newcastle. Perhaps the largest arterial system, the US interstate, was started after World War II as a national defence system. The construction of the 41, 000 miles system was approved in 1956. It was funded by the Federal Government to an extent of 90 per cent, the balance being states matching share. It linked all the major cities of the nation. It is toll-free. USA also pioneered the modern super highway - a limited access, high-speed facility. The Bronx River Parkway constructed in 1925 was the forerunner to many such to come later. The inter-state system of USA The worlds best road system is perhaps in the USA. The interstate system was taken up after the Second World War as a defence system. It is now fully functional. The USA now has a length of 88,400km of express ways, of which 5,000km (6 per cent) was tolled. The remaining length is toll-free. Autobahns of Germany Germany began constructing its express ways, which were known as Autobahns in the late 1920s. Before the start of the Second World War, Germany had about 4,000 km of express ways. The country has now 11,238km of express ways most of which are non-toll.


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6 References

Express ways in France. France started the construction of its express ways in the 1950s. The work was carried out through semi-government public companies. Private companies were involved in the work in the 1970s. The network was developed as a toll system. By 1996, the country had a network of 8,768km of express ways, 72 per cent of which are tolled. Vehicle Ownership Since road transport gives mobility to persons, the vehicle ownership rate has been increasing at a fast rate round the world. Table 1.2 gives a comparison of the car-ownership rate (cars per 1000 persons) in some selected countries. The rate is very high in USA. (One car per two persons), and is currently low in India (one car per 250 persons). This rapid growth calls for modernization of the road system.

Table 1.2: Car Ownership Rates (Cars per 1000 persons) China 3India 4Pakistan 6 Indonesia 10Egypt 19Thailand 22Brazil 76Malaysia 113South Korea 114Japan 342U.K. 248Australia 459Germany 459USA 504 Source: Kadiyali, 2006

1.5.1 References 1. Kadiyali, L.R., 2006. Principles and Practices of Highway Engineering (including

Expressways and Airport Engineering), 4th Edition. Khanna Publishers, New Delhi. 2. Mathew, T.V. and Rao K.V.K., 2007. Introduction to Transportation Transport

Engineering. 3. OFlaherty C.A., 2002. Highways: The Location, Design, Construction and

Maintenance of Pavements. 4th Edition, Oxford, Butterworth Heinemann.


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7 Planning and Layout of Roads

2.0 Planning and Layout of Roads

2.1 Introduction Transport is an important infrastructure for development. It occupies a pivotal position in the growth of developing countries. Planning for economic development is now an accepted tool widely followed in most of the countries. So far there is very little evidence of a scientific approach in planning at the national level in the transport sector. However, the outlays and targets are normally adopted after a careful study of the existing facilities, their deficiencies and immediate needs. Very often it has been experienced that investment decisions are taken after a bottleneck situation develops. The transport plan should be integrated in the countries overall economic plan since transport in its own sake has no meaning. It assumes importance only in as far as its serves the ultimate goal of development i.e. transport plans must translate overall development objectives and potentials into transport requirements [Kadiyali, 2006].

2.2 Goals and Objectives The goals and objectives of the transport plan should be clearly identified and expressed. This alone will facilitate the formulation of a realistic plan. The following points give general guidance in this regard:

a) The transport plan should not conflict with the broad goals and objectives of the national plan for development. It should help in translating the goals and objectives of the national development plan.

b) The transport plan should aim at coordinated development of all modes of transport without prompting unhealthy competition.

c) The transport plan should aim at conserving scarce resources such as oil fuels, coal and electricity.

d) The transport plan should generate employment potential and should favour labour-intensive technologies to the extent feasible and desirable.

e) The transport plan should aim at a balanced development of the country, keeping in view the special needs of inaccessible areas and backward classes of society.

f) The transport plan should aim at a balanced development of rural and urban settlements. While urbanisation is an inevitable result of and a pre-requisite for economic development, growth of cities beyond manageable limits leads to undesirable effects. Transport should be used as a tool for dispersal of activities to result in overall health of the economy.

g) Transport plans should recognise the need to exploit the natural resources of the country and provide for quick exports to earn valuable foreign exchange to developing countries

h) Transport plans should facilitate the growth of new industries, agricultural production and processing of raw materials. Functional linkages between industry and hinterland should be established.

i) Environmental impact of transport plans should be established.


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8 The Project Cycle

2.3 The Project Cycle

2.3.1 Components of the Project Cycle Projects are planned and carried out following a sequence of activities, often known as the project cycle. There are many ways of defining the steps in this sequence but the following terminology will be used here:

1) Problem identification 2) Pre-feasibility 3) Feasibility 4) Design 5) Procurement and negotiation 6) Implementation 7) Operation 8) Monitoring and evaluation.

The first three steps (1-3) make up the planning phases of the project cycle, though evaluation (step 8) may also be considered integral to the planning process by providing feedback on the wisdom and processes of past decisions. Figure 2.1 provides an outline of the stages of the project cycle. The planning phases of the cycle involve a gradual process of screening and refining alternative options (for resolving an earlier identified problem). In this process there are clear decision points (at the end of each stage) when potential projects are either rejected or taken forward for further and more detailed analysis. Dubious projects should be rejected at an early planning stage (and before feasibility) as they gain a momentum of their own, and hence become increasingly difficult to stop at the later stages in the cycle when minor changes of detail are often all that are possible. Within each of the planning phases (project identification, pre-feasibility and feasibility), the same basic process of analysis is adopted. Differences occur largely in the level of detail applied. Sometimes phases are merged, with pre-feasibility becoming an extension of the project identification, or a first step in the feasibility stage [TRL, 2005].

2.3.2 Problem Identification The first stage of the cycle is to find potential projects. General planning identifies key transport constraints and sketches solutions at a global or macro level, and should prioritize these as to the need and urgency for resolution. The planning process takes into account government policies and programmes (in all relevant sectors) which impact on transport development. The need for general road development is therefore examined in a very wide socio-economic and policy-orientated context. The framework for general planning could be cross-sectoral in nature or it could also be focused specifically on transport issues. In all cases, however, the scope is macro in nature, taking in a complete region or city. Examples of such spatial (or structure) plans and transportation studies include:

a) A national or regional development study (e.g. regional spatial plans) b) An urban development study (or master plan) c) A national or regional transport study (sometimes known as a multi-modal or inter-

modal transport study) d) An urban land-use/transportation study e) An integrated rural accessibility plan f) A road safety strategic plan


9

9

9 Pre-feasibility

2.3.3 Pre-feasibility At the start of the pre-feasibility stage there is a clearly defined transport problem (identified in general planning), but no strong evidence that this problem could be solved by road improvement, or any other transport solution (e.g. improvements to transport services) in an environmentally or economically acceptable manner. By the end of the pre-feasibility stage, there will be clear evidence whether or not a road improvement project is worthwhile. If it is, the pre-feasibility will normally identify what type of project would be suitable, checks that the project is not premature and provides the information needed to commission a feasibility study. Typically, this phase might identify corridors that require a new road. An affirmative pre-feasibility study will also trigger the inclusion of a line-item in the long-term road preparation budget (of the ministry or its highway agency). It gives advance warning that monies will need to be budgeted for the future implementation of this particular project. The pre-feasibility study may indicate that the proposed road improvement project would not be effective in solving the problem, or should be reconsidered later, perhaps when there is more traffic). In that case the process should be terminated or shelved without incurring the high cost of a feasibility study.

2.3.4 Feasibility The feasibility study finds the most suitable road improvement project for solving or helping to solve an identified transport problem. At the start of the study there is a clearly defined problem with an expectation that the problem can be solved by some form of road improvement, in a manner that is environmentally, socially and economically acceptable. This expectation is backed up by the evidence needed to justify the considerable cost of carrying out a feasibility study (identified in a pre-feasibility study). The level of detail of this study will depend on the complexity of the project and how much is already known about the proposal. By the end of the study there should be a clear recommendation for a specific road improvement project. The study will provide evidence that this particular project should be carried out and that this project provides the most suitable solution to the problem, taking into account its operational benefits and its environmental and economic implications. It will also provide a detailed description and a preliminary engineering design (PED) and associated drawings of the proposed project to enable costs to be determined at a level of detail to enable funding decisions to be made. The feasibility study will also provide an input to the road preparation budget process, giving greater detail (than earlier phases) of costs that will be incurred and project timings.

2.3.5 Design The final engineering design (FED) is often very costly (up to 15 per cent of project costs) and usually follows provisional commitment to the project. Numerous decisions which will affect economic performance are taken throughout design; and economic appraisal often results in redesign. In this stage, working drawings and bills of quantities are normally prepared.

2.3.6 Commitment and negotiation Commitment of funds often takes place in a series of stages. This is followed by invitations to tender and negotiations with contractors, potential financiers and suppliers. At this stage, there are still considerable uncertainties.


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10 Implementation

2.3.7 Implementation Several aspects of the earlier stages in the project cycle will affect the success of the implementation. The better and more realistic the plan, the more likely it is that the plan can actually be carried out and the full benefits be realised. A flexible implementation plan should also be sought. It is almost inevitable that some circumstances will change during the implementation. Technical changes may be required as more detailed soils information becomes available or as the relative prices of construction materials change. Project managers may need to change and re-plan parts of the project to take account of such variations. The more innovative and original the project is the greater is the likelihood that changes will have to be made during implementation.

2.3.8 Operation This refers to the actual use of the road by traffic; it is during this phase that benefits are realised and maintenance is undertaken.

2.3.9 Monitoring and Evaluation The final phase of the project cycle is evaluation. This consists of looking back systematically at the successful and unsuccessful elements of the project experience to learn how planning can be improved in the future. For evaluation to be successful, it is important that data about the project is collected and recorded in a systematic way throughout all stages of the project cycle. Without this, it is usually impossible to determine details of events and information that were available during periods leading up to the taking of important decisions. Evaluation may be carried out by many different people. The sponsoring organisation or external agency may undertake evaluation. In large and innovative projects, a separate unit may be needed to monitor each stage of the project by collecting data for identifying problems that need to be brought to the attention of the project's management. In some cases, outside staff will be used to provide an independent audit and specialist university staff may well be suited to undertake such a task. The evaluation should result in specific recommendations about improving aspects of the project design which can be used to improve ongoing and future planning.

2.4 Overview of Road Appraisal in Developing Countries Feasibility studies of road schemes in developing countries are undertaken along the following steps:

1) Define objectives 2) Determine alternative ways of meeting objectives 3) Make preliminary considerations 4) Asses traffic demand 5) Design and cost different options 6) Determine benefits of each alternative 7) Economic analysis and comparison of alternatives 8) Recommendations

The steps are not necessarily sequential and involve iteration. The above steps will now be discussed:


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11 Define Objectives

2.4.1 Define Objectives A road project is wherever possible set against the background of a national or regional transport plan or at least a road plan. Definition of project objectives provides the basic framework for carrying out feasibility studies. The objective of providing a new road could be any of the following:

a) To support some other developmental activity; b) To provide fundamental links in the national or a district road network; c) To meet a strategic need; d) To increase the structural capacity or traffickability of an existing road to cope with

higher traffic flows; e) To provide an alternative to an existing transport link or service; f) To address a major safety hazard, environmental or social problem; g) To rectify damage or failure that has caused sudden deterioration of the existing

road.

Depending on the objectives of the investment, the project is appraised against different sets of criteria. Development Banks like World Bank and the Asian Development Bank are increasingly getting involved in strategic planning of road networks in developing countries. This calls for alignment of a countrys Transport Plan with a Development Banks country strategy.

2.4.2 Determining alternative ways of meeting Objectives This may involve making a modal choice say between rail, road, air and water transport to solve a transport problem or deciding between different technical solutions to highway problems. These technical solutions include:

a) Upgrading and new construction Upgrading projects aim at providing addition capacity for a road towards the end of its design life or because of a change in route function. Examples are paving of gravel roads and providing overlays on paved roads;

b) Reconstruction and rehabilitation - Major repair on an existing road;

c) Stage construction Planned improvements are made to the pavement standards of

a road at fixed stages through the project life. Although stage construction may be appropriate in achieving an optimal economic balance, practice has shown that budgetary constraints have often prevented later upgrading phases of stage construction projects leading to lower rates of return.

d) Maintenance projects These consist of either building up the institutional

capability of the maintenance organisation to improve its efficiency or overcoming a short term problem through project specific interventions like surface dressing, supply of maintenance equipment and technical assistance. The later type of project could be a component of the former.

Community involvement in the early stages of development of projects in developing countries is now recognised as fundamental for project success because of the local wealth of knowledge possessed by the community concerning the solution to a problem in the context of an areas physical and socio economic constraints.


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12 Preliminary considerations

2.4.3 Preliminary considerations The underlying issues are taken into account during the feasibility study:

a) Analysis period and design life Most road projects are analysed on a 15 year time horizon. The analysis period may be partly dictated by the nature of the investigation. For example, long periods are useful when comparing mutually exclusive projects, whereas short periods may be appropriate for small projects (such as regravelling of rural access roads), where the life of the investment is expected to be limited to a few years.

b) Uncertainty and risk Projects in developing countries are always set against a

background of economic, social and political uncertainty to some degree. The steps taken to reduce uncertainty include risk analysis using probabilistic techniques for well defined projects and scenario analysis in explanatory projects.

c) Choice of technology According to the Transport and Road Research Laboratory

(TRRL, 1998), engineers have to decide between mechanised and labour based techniques in preparing designs and specifications of works.

d) Institutional issues The major institutional issues to be considered include:

The institutional framework in which the roads are set including the aspects of organising, staffing, training, procedures, planning, maintenance, funding and controls.

Strengthening the institutions responsible for implementing the project; and The funding and maintenance capability of road maintenance organisations. Legislative requirements of the study (if applicable)

e) Socio-economic considerations The major issues that are assessed in terms of the

impact of the project on the target community are social changes, construction consequences, road accidents, severance, minorities like gender issues and availability of local expertise and resources.

f) Environmental Conditions The impact of the road project on the surrounding environment is taken into consideration. The impact is more significant for new projects penetrating an undisturbed country tan for upgrading projects because the latter usually follow an existing alignment.

2.4.4 Assess Traffic Demand For the purpose of geometric design and evaluation of economic benefits, the volume and composition of current and future traffic needs to be known. For structural design purposes of paved roads, the axle loading of only heavy goods vehicles is relevant thus for this purpose traffic appraisal considers volumes of Heavy Goods Vehicles (HGVs). The Road Maintenance Initiative (RMI) (World Bank, 1998) observes that far too few countries in Africa have permanent road data banks, locally managed and regularly updated, based on objective technical data.

2.4.5 Design and Cost different Options Cost estimates should encompass analytical techniques and rigorous procedures of risk management to produce realistic estimates. The major activities undertaken in this step include: Route location, pavement design, geometric design and design of drainage


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13 Determine Benefits of each Alternative

structures. In this stage an optimal balance between cost of provision and user cost is important.

2.4.6 Determine Benefits of each Alternative Estimates are made of both the costs associated with the project and the benefits expected to occur. The benefits normally considered are:

a) Direct savings in the cost of operating vehicles b) Economies in road maintenance c) Time savings by travellers and freight d) Reduction in road accidents e) Wider effects on the economic development of the region

2.4.7 Economic Analysis and comparison of alternatives The best option representing the option with the minimum level of maintenance is carefully chosen and used as a basis against which other options are compared. A cost benefit analysis procedure is then used to assess the net contribution the road investment makes to the country as a whole. The cost benefit analysis uses either Net Present Value (NPV) or Internal Rate of Return (IRR) rules. A positive NPV means a project is justified at the given discount rate. Results of financial, social and environmental appraisals are also considered in deciding the best project. The IRR acts as a guide to the profitability of the investment but gives no indication of the costs or benefits of the project. A difficult approach is normally required for rural access projects so that the cost of the appraisal is justified in terms of project costs. All investment decisions have political, social and environmental consequences besides economic effects. According to TRRL (1998), in planning main road investment, economic/engineering implications are usually paramount in the decisions to upgrade existing road surfaces. Foster (2000) observes that the financial aspects of the project appraisal receive more systematic treatment than non-financial aspects.

2.4.8 Recommendations The feasibility study report marks the end of the appraisal process and recommends whether the project should go ahead and the standards to which it should be built. The depth and detail to which the report covers certain aspects depends on who the report is being made for. An analysis carried out for a development bank covers financial aspects very thoroughly. Projects prepared for aid agencies normally dwell heavily on the socio-economic factors.

2.5 A Typical Road Project Appraisal Process in Uganda This section will be based upon the process that was followed for the feasibility study of the Kampala-Fort Portal Road.


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14 A Typical Road Project Appraisal Process in Uganda

Figure 2.1: Typical Road Project Appraisal in Uganda Source: MoWH&C, 1998 The process shown in the figure above will now be described: Step 1: Objectives The study objectives were derived from two major sources namely:

a) The 10 year road sector development programme (RSDP); b) The strategy related to the Trans-African Highway.

1. Objective 2. Problem Identification

3. Determine Alternatives

4. Project Strategy

5. Engineering, Economic and Environmental analyses

6. Draft Recommendation for preferred solution

7. Review by Ministry of Works, Housing and Communications

8. Finalisation of Recommendation

9. Submission for Funding

10. Detailed Design, Tender and Construction

11. Post Implementation Review


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15 A Typical Road Project Appraisal Process in Uganda

Step 2: Problem identification Past feasibility studies from 1972 to 1995 were used as a basis for establishing the existing problems on the Kampala to Fortportal road. Step 3: Determine alternatives The pre-appraisal study by GIBB consultants on behalf of Danida brought together information from steps 1 and 2 above and challenged the assumptions made in previous studies. Arising out of this study were five options for further evaluation. Step 4: Project strategy Arising out of the results the pre-appraisal study in step 3 above, a draft project strategy was prepared consisting of a two stage construction strategy. Step 5: Engineering, Economic and Environmental analysis Danida as the financier commissioned COWI-DRD to carry out further engineering, economic and environmental analysis on the project strategy and compare different upgrading options under the strategy with the existing route under optimal and prevailing maintenance respectively over 16 study sections. Traffic studies were part of the economic evaluation.

Step 6: Draft recommendations on preferred solution Resulting from the analyses in step 5, recommendations were made on the feasibility of options along an environmentally preferred route alignment in terms of Economic Internal Rate of Return (EIRR). Step 7: Review by Ministry of Works, Housing and Communications In Uganda, step 1 to 6 usually lead to the production of a draft detailed engineering report three (3) months from the start of the study. The report is reviewed by the Ministry of Works, Housing and Communications on behalf of Government as the client leading to comments that are taken into account in preparing the final detailed engineering report (Ministry of Works, Housing and Communications, Gauff Ingenieure, 1993). Step 8: Finalising recommendations Adjustments are made to the draft report in accordance with the recommendations of the client. The consultant then concludes the final report 30days from the receipt of information from the (MoWH&C and Gauff Ingenieure, 1993). Step 9: Submission for funding On conclusion of recommendations, the Ministry of Works, Housing and Communications would submit the feasibility study report to the financier as was the case in the 1993 study by Scott Wilson Kirkpatrick. The consultants would then submit the reports to the financier as their employer. Step 10: Detailed design, Tender and Construction If the financier approved the study, funds would be released for detailed design, tender and construction of the road.


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16 Economic Evaluation of Highway Projects

Step 11: Post implementation review External financiers like the World Bank usually evaluate a project when it is handed over to the client to assess success and compliance with objectives. Such reviews provide valuable lessons as inputs into subsequent projects to improve on project success. Interestingly, the study period for the Kampala-Fort portal road took 26years (1972-1998). Yet the process would ordinarily take three years.

2.6 Economic Evaluation of Highway Projects

2.6.1 Role of Economic Evaluation A developing country like Uganda has serious shortages of resources needed for economic development. The outlay for various sectors of economic activity is decided by planning at the national level, keeping in view the national goals and policies. Within the allocation earmarked for the highway sector, a number of schemes can be taken up, each enjoying its own urgency and attractiveness. It thus becomes necessary to screen and evaluate the various alternatives so that a wise decision can be reached on the most appropriate choice. This is achieved by modern techniques of economic evaluation of projects [Kadiyali, 2006].

Economic evaluation is a rational approach at quantifying the future benefits and costs of proposed highway improvements with a view to determine the extent to which the projects will contribute to the goal of raising the living standard of the people and their general welfare. It provides for a systematic and unbiased procedure for selection of schemes for implementation under the Ten Year Road Sector Development Plans. It ensures that the most worthwhile projects are given the highest priority.

Economic evaluation of highway projects can also be carried out to weigh other alternative transport projects, such as railway projects, pipe-lines or inland water transport projects, in order to select the most beneficial scheme. The following are some of the specific objectives in carrying out an economic evaluation:

1. To decide whether the scheme under consideration is worth investment at all; 2. To rank schemes competing for scarce resources in order of priority; 3. To compare various alternative schemes and select the one most economical; 4. To assist in phasing the programme (stage construction) depending upon the

availability of resources.

2.6.2 Some Basic Principles Economic evaluation involves a number of basic principles discussed below:

a) Economic evaluation makes it possible to choose the best of the various alternatives. The question before the analyst is to suggest the most attractive of them. Often the choice is between do-nothing, and other improvement schemes.

b) In economic evaluation, all past actions are irrelevant. What is of prime importance is the future flow of costs and benefits.

c) In highway projects, the appraisal is carried out from the view-point of the nation as a whole, and is not restricted to any sub-set like the highway agency, truckers, private motorists and bus operators.

d) Economic analysis should not be misunderstood with financial analysis.


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17 Time Value for Money

e) Economic evaluation should take place within a set of established criteria such as minimum attractive rate of return, interest rate etc.

f) Opportunity cost of capital and resources should be considered wherever they are important.

g) The period of analysis need not be too long in view of the uncertainties associated with the future traffic and benefits. In any case, the discounted cash flows of a distant future period are insignificant. For highway projects, it is enough if the analysis covers a period 15-25 years after opening to traffic.

2.6.3 Time Value for Money The fundamental premise on which all methods of economic evaluation rests is that money earns income over a period of time. For example, US$ 100 today will be worth US$ 672.75 at the end of 20 years if invested at 10 per cent compound rate of interest. So also, a sum of US$ 672.75 which might become due to an individual after 20years from today is worth only US$ 100 at the present, assuming the same rate of interest. These facts point to the need for devaluing the future benefits and costs to the present time to determine their present worth. The process of calculating the present worth of a future payment is known as discounting and the interest rate used is called the discount rate. The following formulae are very useful in dealing with the problems in economic evaluation:

a) The amount A to which US$ 1 will increase in n years with a compound interest rate of r will be given by; 1 . 2.1

b) The present value P of US$ 1, n years therefore when discounted at a rate r will be

given by;

1

1 1 . 2.2

2.6.4 Costs and Benefits In economic evaluation, the main objective is to compare the costs and benefits of various alternative schemes and select the one, most advantageous. The first step is, therefore to determine the costs and benefits. There is a great deal of confusion in the designation of what constitutes costs and what constitutes benefits. The simplest description is that the negative effects of a scheme constitute the costs. They indicate the cash out-flows. On the other hand, the positive effects are called benefits and they represent cash in-flows. As long as sufficient care is taken to see that the signs are assigned properly, it is immaterial whether the economic consequence is labelled as costs or benefits.

Costs and benefits can be traced to the provider of the facility (highway department), the highway users and non-users. In economic analysis, since all consequences are to be considered, the costs and benefits to all parties are to be reckoned.

Some consequences can be quantified into monetary terms whereas some cannot. The aim of the analyst should be to quantify as many elements as can be monetarily quantified. Those which cannot be ultimately quantified into monetary terms are kept separately apart and a judgement value can be accorded to them before a final decision is taken.


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18 Costs and Benefits

The economic evaluation of highway projects is generally done by computing the total transport cost which consists of the following components:

a) Cost of construction of the facility b) Cost of maintenance of the facility c) Road user cost d) Cost to the society

The Government, which is often the agency providing the facility, incurs expenditure on constructing a road. This includes land acquisition, earthwork, road pavement and structures. The government also invests money on maintenance and up keep annually. The road user cost, which is borne by the actual user of the highway facility (passenger, crew of vehicles, operator, consignor of goods, pedestrian, cyclist etc.) is composed of:

a) Vehicle operating costs

i) Fuel; ii) Lubricants;

iii) Tyre; iv) Spare parts; v) Maintenance labour;

vi) Depreciation; vii) Crew costs; and

viii) Fixed costs such as: Interest on capital Insurance Taxes Registration fee Grading charges Fines, tolls, etc Permit charges Loading and unloading charges Commission on booking Overhead charges such as rent, salary, electricity, postal, telephone,

stationery

b) Travel Time Cost i) Time value of vehicle occupants

ii) Time value of goods in transit iii) Time value of vehicles in transit

c) Accident Costs

i) Cost of fatality ii) Cost of injuries

iii) Cost of damages to property

d) Cost to Society i) Impact on the environment (noise pollution, air pollution, vibration).

ii) Loss of aesthetics iii) Changes in land values iv) Land severance v) Discomfort and inconvenience.


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19 Costs and Benefits

Benefits from highway projects in effect represent the difference in costs with the new facility and the old facility. Benefits can be grouped under the following:

a) Benefits to the existing traffic, by way of reduced road user costs. b) Benefits to the generated traffic c) Benefits to traffic diverted from other routes and modes d) Benefits to traffic operating on other routes and modes where reduction in traffic has

been caused by the opening of the facility. Vehicle operating costs are affected by a number of factors such as:

a) Vehicle Factors i) Age

ii) Make iii) Horse-power, engine capacity iv) Load carried v) Condition of Vehicle

vi) Level of maintenance input vii) Type of fuel used

viii) Type of tyres (rayon, nylon, radial ply, cross ply etc.)

b) Roadway Factors i) Roughness of the surface

ii) Type of the surface iii) Horizontal curvature iv) Vertical profile v) Pavement width

vi) Type and condition of shoulder vii) Urban and rural location

viii) Number of junctions per km

c) Traffic Factors i) Speed of travel

ii) Traffic volume and composition.

d) Environmental Factors i) Altitude

ii) Rainfall iii) Temperature

Research has shown that the vehicle operating cost components are closely governed by (i) roadway factors such as roughness, pavement width, rise and fall and horizontal curvature, (ii) vehicle factors such as age and load carried and (iii) traffic factors such as speed and volume of traffic. It follows therefore, that good roads result in lower vehicle operating costs. Highway improvements result in speedier travel. Savings in travel time are enjoyed by occupants of vehicles, goods in transit and the vehicles in transit Road accident rates are governed to a certain extent by the condition of the road. Highway improvements can thus bring about a reduction in road accidents. The cost of road accidents, which have been eliminated by highway improvements, represents a benefit.


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20 Evaluation Techniques

When carrying out economic analysis, costs and benefits are considered exclusive of taxes. Taxes do not represent an economic cost and represent only a transfer within the community. Insurance premiums are also excluded from economic analysis since the savings in accidents already account for this element. In a developing country, there are certain resources which are scarcer than the others. The prevailing market prices, therefore, do not reflect the true economic value of the resources. In order to correct such distortions and imperfections, shadow pricing is done. A case in example is the cost of imported fuel in Uganda. Since foreign exchange reserves are very precious, such imported items are shadow priced at a higher value than the market price when carrying out the economic evaluation. Similarly, unskilled labour is surplus in Uganda and the prevailing wage rate (which is statutorily fixed) may not truly reflect this situation. A shadow-pricing of such labour at a slightly lower level would be appropriate. Inflation is disregarded in economic analysis, as it is generally assumed that all prices increase in the same proportion, but relative prices remain constant. But if differential inflation is expected to occur among commodities, necessary adjustments need to be made.

2.6.5 Evaluation Techniques The methods commonly adopted for economic evaluation are:

a) Net present value (NPV); b) Benefit/cost Ratio (B/C Ratio); c) Internal Rate of Return (IRR); d) First Year Rate of Return (FYRR).

a) Net present value (NPV) Method

The NPV method is based on the discounted cash flow (DCF) technique. In this method, the stream of costs and benefits associated with the project over its time horizon is calculated and is discounted at a selected discount rate to give the present value. Benefits are treated as positive and costs are treated as negative. Any project with a positive NPV is treated as acceptable. In comparing more than one project, a project with the highest NPV is selected. The NPV is algebraically expressed as:

1

. 2.3

Where;

NPV0 = Net Present Value in the year 0; Bi = Value of benefits which occur in the year i; Ci = Value of costs which occur in the year i; r = Discount rate per annum; n = Number of years considered for analysis.

b) Benefit-cost (B/C) Ratio Method

There are a number of variations of this method, but a simple procedure is to discount all costs and benefits to their present worth and calculate the ratio of the benefits to costs. Negative flows are considered costs, and positive flows as benefits. Thus the savings in the transport costs are considered as benefits. If the B/C ratio is more than one, the project is worth undertaking.


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21 Evaluation Techniques

1

1

. 2.4

Where C is the total cost of the project In the AASHTO practice of road user analysis the B/C ratio expresses the ratio of the net annual benefits to the net annual costs. The benefits are determined for a simple reference year, which for convenience can be the first year of operation after construction or the median year of the analysis period [Kadiyali, 2006].

c) Internal Rate of Return (IRR) Method The internal rate of return is the discount rate which makes the discounted future benefits equal to the initial outlay. In other words, it is the discount rate at which the present values of costs and benefits are equal i.e. NPV = 0. Calculation of the IRR is not as straight forward as for NPV and is found by solving the following equation for r;

1

0 . 2.5

Solutions are normally found graphically or by iteration. However, with a computer program, the work is rendered simple. The IRR gives no indication of the sizes of the costs or the benefits of a project, but acts as a guide to the profitably of the investment [Thagesen, 1996]. If the internal rate of return calculated from the above formula is greater than the rate of interest obtained by investing the capital in the open market, the scheme is considered acceptable.

d) First Year Rate of Return (FYRR) Method The FYRR is simply the present value of the total costs expressed as a percentage of the sum of benefits in the first year of trafficking after project completion. Thus FYRR is given by;

,% 1100

. 2.5

=

+= 1

0

1)1(100 j

j

ji

j

rC

BFYRR .... (2.6)

Where j is the first year of benefits, with j = 0 in the base year, and other notation is as before. If the FYRR is greater than the planning discount rate, then the project is timely and should go ahead. If it is less than the discount rate, but the NPV is positive, the start of the project should be deferred and further rates of return should be calculated to define the optimum starting date.


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22 Comparison of the Various Methods of Economic Evaluation

It is should be noted that the results of the cost-benefit analysis are no better than the assumptions and input data on which it is based. The data and parameters used in the analysis of a road project can be prone to substantial errors and it is important to recognise that these exist and to take steps to minimise them [Thagesen, 1996].

2.6.6 Comparison of the Various Methods of Economic Evaluation The three methods of economic evaluation described above have their own advantages and short comings. The B/C ratio method is very widely used by the highway engineers. It, however, suffers from the following drawbacks:

a) It requires an assumption of a discount rate, which should bear relation to the opportunity cost of capital. It is however, rather difficult to know the opportunity cost of capital accurately.

b) The significance of the B/C ratio is ambiguous, and its relative value is difficult to understand and interpret. For instance, if there are two proposals, one with a B/C ratio of 1.05 and the other with a ratio of

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