Introduction to Highway Engineering

In this chapter, we shall discuss about an introductory part of Highway Engineering which is considered as an important branch of transportation engineering so as to have the basic knowledge about importance of highway transportation, history of development of roads in India, classification of roads, organization of the state highway department etc.

What is highway engineering?

Highway engineering is one of the branches of civil engineering. It deals with the process of design, construction and maintenance of different types of roads in India.

Scope of Highway engineering:

Apart from the design, construction and maintenance of different types of roads, highway engineering also includes the study of the following topics:

· Development, planning and locations of roads;

· Materials required for their construction

· Highway traffic performance and its' control

· Drainage of roads etc.

Important technical terms related to roads:

Some important terms having immediate concern with highway engineering are discussed below:

• Road:

A public through fare over which vehicles, cyclists, pedestrians etc. may lawfully move from one place to another is called a road or highway.

Usually, the term highway is used for an important road of national or state importance in a country.

• Traffic:

The vehicles, cycles, carts, pedestrians etc. traveling together on a road constitute the traffic.

• Foot way:

The portion of roadway of an urban road reserved only for pedestrians is called foot path, side walk or foot way. The minimum width of side walk should be 1.5 meters.

• Cycle track:

The portion of roadway of an urban road reserved only for bicycles is called cycle track. The minimum width of cycle track should be 2 meters.

• Motor way:

The portion of roadway of an urban road reserved for use only by high speed and power driven vehicles is called motor way, express way or super highway.

The land width for an express way is recommended as 50 to 60 meters. The function of express way is to cater for movement of heavy volumes of motor traffic at high speeds.

Importance of highway transportation:

Considering the utility of roads anywhere in the different parts of a country; they can be rightly compared to arterials in a human body.

Just as arteries maintain man's health by providing circulation of blood; similarly Roads promote nation's wealth by keeping its people and goods moving. Thus, we see that progress and well-being of a nation depends much on roads. In fact, roads are the life lines of nation's economy.

The importance or necessity of highway transportation can be easily judged from the following purposes or advantages of roads:-

• They facilitate, conveyance of people, goods, raw-materials, manufactured articles etc. speedily and easily in the different parts of a country.
• They act as the only source of communication in regions of high altitudes i.e. in mountainous regions.
• They help in growth of trade and other economical activities in and outside the villagers and towns by establishing contact between towns and villages.
• They help in providing efficient distribution of agricultural products and natural resources all over the country.
• They help in price stabilization of commodities due to mobility of products all over the country.
• They help in cultural and social advancement of people and making the villagers active and alert members of the community.
• They help in promoting the cultural and social ties among people living in different part of a country and thus strengthen the rational unity.
• They help in providing improved medical facilities quickly to human beings, especially to those who live in rural areas.
• They provide more employment opportunities.
• They enhance land value and thus bring better revenue.
• They serve as feeders for airway, waterways and railways.
• They help in reducing distress among the people, caused due to famine, by supplying them food and clothing quickly.
• They help in maintaining better law and order in a country.
• They play a very important role in the defense of a country during war days.
• Lastly, it can be said that roads are the symbol of a country's progress and thus development made by any country can be judged by the quality and network of its road system.

Highway development in India:

Excavations in the sites of Indus valley, Mohenjo-dero and Harappan civilizations revealed the existence of planned roads in India as old as 2500-3500 BC. The Mauryan kings also built very good roads. Ancient books like Arthashastra written by Kautilya, a great administrator of the Mauryan times, contained rules for regulating traffic, depths of roads for various purposes, and punishments for obstructing traffic.

During the time of Mughal period, roads in India were greatly improved. Roads linking North-West and the Eastern areas through gangetic plains were built during this time.

After the fall of the Mughals and at the beginning of British rule, many existing roads were improved. The construction of Grand-Trunk road connecting North and South is a major contribution of the British. However, the focus was later shifted to railways, except for feeder roads to important stations.

Modern developments

The first World war period and that immediately following it found a rapid growth in motor transport. So need for better roads became a necessity. For that, the Government of India appointed a committee called Road development Committee with Mr.M.R. Jayakar as the chairman. This committee came to be known as Jayakar committee.

Jayakar Committee

In 1927 Jayakar committee for Indian road development was appointed. The major recommendations and the resulting implementations were:

• Committee found that the road development of the country has become beyond the capacity of local governments and suggested that Central government should take the proper charge considering it as a matter of national interest.
• They gave more stress on long term planning programme, for a period of 20 years (hence called twenty year plan) that is to formulate plans and implement those plans with in the next 20 years.
• One of the recommendations was the holding of periodic road conferences to discuss about road construction and development. This paved the way for the establishment of a semi-official technical body called Indian Road Congress (IRC) in 1934.
• The committee suggested imposition of additional taxation on motor transport which includes duty on motor spirit, vehicle taxation, and license fees for vehicles plying for hire. This led to the introduction of a development fund called Central road fund in 1929. This fund was intended for road development.
• A dedicated research organization should be constituted to carry out research and development work. This resulted in the formation of Central Road Research Institute (CRRI) in 1950.

Central Road Fund (CRF), 1929

• On recommendation of the Jayakar committee, the central road fund was enforced on first march, 1929.
• The petrol tax surcharge at the rate of two annas per gallon (2.64 paise per liters) of the petrol consumed by motor traffic was imposted to build the road development fund.
• Out of annual revenue, thus collected, 20% was to be retained by the central government. for meeting expenses on the on the administration purpose, research and the development of roads under it's charge.
• The balance 80% of the central road fund was to be distributed among the provinces, according to their petrol consumption, for maintenance and construction of roads.

Indian Road Congress (IRC), 1934

The Indian Roads Congress (IRC) is the Apex Body of Highway Engineers in the country. The IRC was set up in December, 1934 on the recommendations of the Indian Road Development Committee best known as Jayakar Committee set up by the Govt. of India with the objective of Road Development in India.

• To promote and encourage the science and practice of building and maintenance of roads;
• To provide a channel for the expression of collective opinion of its members regarding roads;
• To promote the use of standard specifications and to propose specifications;
• To advise regarding education, experiment and research connected with roads;
• To hold periodical meetings, to discuss technical questions regarding roads;
• To suggest legislation for the development, improvement and protection of roads;
• To suggest improved methods of administration, planning design, construction, operation, use and maintenance of roads;
• To establish, furnish and maintain libraries and museums for furthering the science of road making;
• To publish, or arrange for the publication of proceedings, journals, periodicals and other literature for the promotion of the objects of the Society;
• To accept subscriptions, subsidies, donations, endowments and gifts in furtherance of the objects of the Society;
• To grant pay, prizes, honoraria, or scholarships (including traveling scholarships) for meritorious work in furtherance of the objects of the Society.

Nagpur road congress 1943

The Second World War saw a rapid growth in road traffic and this led to the deterioration in the condition of roads. To discuss about improving the condition of roads, the government convened a conference of chief engineers of provinces at Nagpur in 1943. The result of the conference is famous as the Nagpur plan.

A twenty year development programme for the period (1943-1963) was finalized. It was the first attempt to prepare a co-ordinated road development programme in a planned manner.

The roads were divided into four classes:

• National highways which would pass through states, and places having national importance for strategic, administrative and other purposes.
• State highways which would be the other main roads of a state.
• District roads which would take traffic from the main roads to the interior of the district. According to the importance, some are considered as major district roads and the remaining as other district roads.
• Village roads which would link the villages to the road system.

The committee planned to construct 2 lakh kms of road across the country within 20 years.

They recommended the construction of star and grid pattern of roads throughout the country.

One of the objectives was that the road length should be increased so as to give a road density of 16kms per 100 sq.km.

Central road research institute:

In 1950, Central Road Research Institute (CRRI) was started at New Delhi. This institute is considered as one of the National laboratories of the Council of Scientific and Industrial Research in India. This institute is mainly engaged in applied research and offers technical advice to state governments on various problems concerning to roads.

National highway act:

In 1956, the National Highway Act was passed. According to this act, the responsibility of development and maintenance of National Highways was given provisionally to the central government.

Bombay road congress 1961:

The length of roads envisaged under the Nagpur plan was achieved by the end of it, but the road system was deficient in many respects. The changed economic, industrial and agricultural conditions in the country warranted a review of the Nagpur plan. Accordingly a 20-year plan was drafted by the Roads wing of Government of India, which is popularly known as the Bombay plan. The highlights of the plan were:

• It was the second 20 year road plan (1961-1981)
• The total road length targeted to construct was about 10 lakhs.
• Rural roads were given specific attention. Scientific methods of construction were proposed for the rural roads. The necessary technical advice to the Panchayaths should be given by State PWD’s.
• They suggested that the length of the road should be increased so as to give a road density of 32kms/100 sq.km
• The construction of 1600 km of expressways was also then included in the plan.

Lucknow road congress 1984:

This plan has been prepared keeping in view the growth pattern envisaged in various fields by the turn of the century. Some of the salient features of this plan are as given below:

• This was the third 20 year road plan (1981-2001). It is also called Lucknow road plan.
• It aimed at constructing a road length of 12 lakh kilometres by the year 1981 resulting in a road density of 82kms/100 sq.km.
• The plan has set the target length of NH to be completed by the end of seventh, eighth and ninth five year plan periods.
• It aims at improving the transportation facilities in villages, towns etc. such that no part of country is farther than 50 km from NH.
• One of the goals contained in the plan was that expressways should be constructed on major traffic corridors to provide speedy travel.
• Energy conservation, environmental quality of roads and road safety measures were also given due importance in this plan.

Classification of roads:

Roads are classified into different categories as under:-

• According to location
• According to importance
• According to traffic
• According to tonnage

Classification of roads according to location:

According to location and financial responsibility, non-urban roads in India are classified into the following five categories:-

• National Highways (NH)
• State Highways (SH)
• Major District Roads (MDR's)
• Other District Roads (ODR's)
• Village Roads (VR's)

This classification of roads was done as per recommendations made in the Nagpur plan finalized the Indian Roads Congress in 1943. This classification is, therefore, popularly known as IRC classification of road.

The different categories of roads according to this classification are discussed below:-

1. National highways:

The main highways running through the length and breadth of the country connecting major parts, foreign highways and capitals of states etc. are known as National Highways (NH's).

These highways constitute the main arteries of transport in the country and are also of military importance. National highways should have the carriageway of atleast two lane widths. They should have the modern type of surfacing. The responsibility of construction and maintenance of these roads lies with the central govt.

2. State highways:

The highways linking the district headquarters and important cities within the state or connecting them with National highways or with highways of the neighboring states are known as state highways (SH's).

These highways are also called provincial highways. These highways serve as arterial routes of traffic to and from district roads within the state. State highways should preferably be of two lane width. They should also have a modern type of surfacing. The responsibility of construction and maintenance of these road lies with state governments. However, the central government gives grant for the development of these roads.

3. Major district roads:

The important roads within a district serving areas of production and markets and connecting these places with each other or with the main highways are known as Major District Roads (MDR's).

4. Other District Roads:

The roads serving rural areas of production and providing them with outlet to market centers, Tehsil head quarters, block development headquarters, railway stations etc. are known as Other District Roads (ODR's).

5. Village Roads:

The roads connecting villages or group of villages with each other or with the nearest road of higher category are known as Village roads.

Road Patterns:

Road network can be laid in various patterns. These patterns in which the road network is laid could be

• Rectangular or Block pattern
• Radial or Star and block Pattern
• Radial or Star and Circular Pattern
• Radial or Star and Grid Pattern
• Hexagonal Pattern
• Minimum Travel Pattern

Road Alignment

The position of the layout of the centre line of highway on the ground is called the alignment.

There are two type of alignment:

1. Horizontal alignment

• Straight Path
• Curves
• Horizontal deviations

2. Vertical Alignment

• Vertical Curves (Summit curves, valley curves)
• Vertical Gradients

The alignment of road should be carefully decided before the construction of road is started. Improper alignment would result in one or more of the following disadvantages:

• Increases in construction cost
• Increases in maintenance cost
• Increases in vehicle operation cost
• Increases in accident rate.

Requirement of Good alignment:

The basic requirement of an ideal alignment are:

1. Short

2. Easy

3. Safe

4. Economical

Short:

It is desirable to have a short alignment between two terminal stations. A straight alignment would be the shortest. Such a route will be cheap in construction and will reduce the time of travel.

Easy:

The alignment should be such that it is easy to construct and maintain the road with minimum problems. Also the alignment should be easy for the operation of vehicles with easy curves and gradients.

Safe:

The alignment should be safe enough for construction and maintenance. Also it should be safe for the traffic operation with safe geometric feature.

Economical:

The highway alignment should be selected in such a way that the total cost including initial cost, maintenance cost and operation cost is brought down to the minimum level.

Factors affecting road alignment:

• Obligatory points
• Traffic
• Geometric design
• Economical
• Other consideration
  • Availability of construction material
  • Proper drainage
  • Geological Features
  • Political consideration
  • Monotony etc.

Highway Project:

In a new highway project, engineer has to plan, design and construct either a network of new roads or a road link. It should contain information such as..

• General details of the project and its importance
• Feature of the road including selection of the route, alignment, traffic etc.
• Road design and specification
• Drainage facilities and cross drainage structures
• Material, labour and equipment
• Rates
• Construction programming and
• Other miscellaneous items like diversion roads, traffic control, road side amenities, rest houses etc.

The following drawings are usually prepared in a highway project;

• Key map
• Index map
• Preliminary survey plan
• Details plan and longitudinal section
• Detailed cross-section
• Land acquisition plans
• Drawings of cross drainage and other retaining structures
• Drawings of road intersections
• Land plans showing quarries etc.