What is Map Study or Paper Location?

The process of marking several possible alternative alignments of a road on the topographic map of the area is known as Map Study or Paper Location.
A topographic map shows the nature of the area by means of contour lines. This map also shows the position  of Obligatory points such as important towns, growing villages, trade and industrial centres, places of historic importance, canals, rivers, railway lines, bridges, etc. These maps are available from Survey Department of India with 15 or 30 m contour interval.
The possible alternative alignments are marked keeping in view the topographical and other features shown on the map.
The following consideration are made while marking a tentative alignment on the map :-

1. The route should be as short as possible.
2. It should be easy for construction, maintenance and traffic oppertions.
3. It should be safe for traffic operations.
4. It should also be economical in its cost of construction, maintenance and traffic operations.
5. It should be of maximum utility.
6. It should satisfy the maximum requirement of road geometrics.
7. It should fit in well the landscape.

What Is Road Drainage? Modes Of Water Penetration

The process of removing and controlling the access of surface and sub-surface water within the right-of-way of a road is called road drainage.

It also include interception ( collection ) and diversion of water from the road surface and the subgrade.
The process of interception and diversion of surface water through suitable side drains is called surface drainage, and the process of interception and removal of sub-soil water through suitable sub-surface drains is called sub-surface drainage.

The main object of road drainage is to keep the road surface and its foundation as dry as possible so as to maintain its stability.

Thus, a good drainage system is essential for efficient highway transportation with minimum maintenance cost.

Modes of water penetration into road structure.

The following are the different modes of water penetration into the road structure:-

1. Surface water from the top of pavement by percolation through caracks and poor pavement surface.
2. surface water from sides of the pavement.
3. sub-soil water from underside of the pavement by capillary rise.
4. sub-soil water from sides of the pavement.
5. Intercepted water due to overflooding of cross drainage works.

Types Of Earth Roads

Earth roads are of the following two types:-

1) Ordinary earth roads :- The earth road having its foundation and wearing surface consisting of one or two compacted layers of natural soil available along its alignment is called an ordinary earth road.
This is the lowest form of pavement surface used so far and is considered as the first stage in the development of road pavement construction. The surface of these roads is generally dusty and ruts are quickly formed. These roads become unserviceable very soon an thus require frequent repair in order to keep them in serviceable condition for a longer period.

2) Stabilized earth roads :- The earth road having its foundation and wearing surface consisting of one or two compacted layers of stabilized soil is called stabilized-earth road.
This is the improved form of earth roads. These roads can carry greater traffic, load and provide better better service as compared to ordinary earth roads.

Construction Of Earth Roads

Earth roads are constructed as detailed below :-
Material required :- The materials required for the construction of an ordinary earth road are natural soil, originally availableat site, a suitable stabilizer, if required. The ideal composition of soil which is recommended for construction earth roads.

Method of construction of an ordinary earth road :- The construction work of an ordinary earth road is completed in the following steps ;-

1. Preparing the subgrade :- The subgrade is prepared and the surface is brought to the required camber and gradient.

2. Rolling an watering :- The surface is rolle properly and well wetted with water.

3. Spreading the soil :- after watering, a layer of graded soil, about 10 cm thick is evenly spread.

4. Rolling :- the layer of soil is rolled at optimum moisture moisture content ( OMC ) with a suitable roller and finally finished with a light roller.

The type of roller for compaction is decided based on soil type, desired amount of compaction and availability of equipment. Atleast 95 per cent of dry density of its light compaction is considered desirable.
Note :- Sometimes, a second layer (about 10 cm thick ) is also spread and rolled properly to act as wearing course.
5. Checking :-The camber of the finished surface is checked an corrected, if necessary.
6. Curing :- The rolled surface is watered for four or five days for curing. No traffic should be allowed to pass over the road surface during this period.
7. Opening to traffic :- After curing, the traffic is allowed to pass but the surface is sprinkled over with water for a period of 10 to 1 days.
Method of construction of a stabilized earth road :- construction work of a stabilized earth road is completed  in steps as described in case of ordinary earth road. for constructing  a stabilized earth road, the subgrade is prepared to the required camber and gradient. Then the base course is prepared by any suitable method of soil stabilized soil ( about 10 cm thick ) is spread over the base course and rolled properly. The surface is then cured and opened to traffic.

Requirements Of A Good Road Aggregate

Road aggregate forms the princpal material in the construction of road pavements. Therefore, it should be of good quality. A good road aggregate should fulfill the following requirements:-

1. Hardness :- A good road aggregate should be sufficiently hard i.e. it should offer maximum possible resistance to abrasion.
This requirement of the road aggregate is particularly needed when it is to be used in flexible pavements. Since flexible road pavements go on distorting under heavy traffic  load,  the road metal is constantly but slightly disturbed. This causes pieces of stones to rub and grind against each other. Therefore, the road aggregate should be hard enough to resist abraison due to grinding of pieces of  stones against each other.

2. Toughness :- A good road aggregate should be quite tough i.e. it should offer the maximum possible resistance to the hammering effect of wheel loads.
This requirement is essential so that the road aggregate used in the construction of flexible pavements can resist the impact caused due to movements of heavy traffic loads without breaking into smaller pieces.

3. Durability :- A good road aggregate should be sufficiently durable i.e. it should be sufficiently resistant to weathering agencies.
This requirement of the road aggregate is essential so that it can resist the effects of weathering agencies like rain, variation of temperature, frost, etc. in order to achieve long life of the road pavement.

4. Strength :- a good road aggregate should have high crushing strength.
This requirement of the road aggregate is essential so that it can withstand safely the stresses developed in the road pavement due to traffic wheel loads.

5. Cementation :- a good road aggregate should have sufficient cementation property i.e. it should have sufficient binding property within itself.
This requirement is essential for road aggregate used in the water bound macadam road surfaces. in such roads, the road aggregate should form its own binding material under the load of road roller and bind itself so that  the road pavements may remain serviceable for a longer period.

6. Adhesiveness :- A good road aggregate should have adhesive property i.e. it should have sufficient binding capacity with the binders.
This requirement is essential of road aggregate used in the bituminous roads. In such roads, the road aggregate should have adequate binding capacity with the binders like bitumen, asphalt. coaltar, etc. so as to ensure stability of the road surface.

Types Of Curves On Hill Roads

The following are the important types of curves provided on hill Roads:-

1. Hair-Pin Curves ;
2. Salient Curves ;
3. Re-entrant Curves.

1. Hair-pin curves :- The curve in a hill road which changes its direction through an angle of 180 degree  or so, downthe hill on the same side is known as hair-pin curve.

A Hair-Pin Bend

This curve is so called because it conforms to the shape of a hair-pin. The bend so formed at the hair-pin curve in a hill road is known as hair-pin bend. This type of curve should be located on a hill side having the minimum slope and maximum stability. It must also be safe from view point of land slides and ground water. Hair-pin bends with long arms and farther spacing are always preferred. They reduce construction problems and expensive protective works. Hair-pin curves or bends of serpentine nature are difficult to negotiate and should, therefore, be avoided as far as possible.

2. Salient curves :- The curves having their convexity on the outer edges of a hill road are called salient curves.

The centre of curvature of a salient curve lies towards the hill side. This type of curve occurs in the road length constructed on the ridge of a hill. the bend so formed at the salient curve in a hill road known as corner   bend.

Salient curves are very dangerous for fast moving traffic. At such a curve or at corner bend, the portion of projecting hill side is usually cut down to improve the visibility as shown in fig. (re-entrant curve). The outer edge of the road at such a curve is essentially provided with a parapet wall for protection of the vehicles from falling downthe hill slope.

3. Re-entrant curves :- The curves having their convexity on the inner edge of a hill roadare called re-entrant curves.

Re-entrant curves

The centre of curvature of a re-entrant curves lies away from the hill side. This type of curve occurs in the road length constructed in the calley of a hill.

These curves are less dangereous as they provide adequate visibility to the fast moving traffic. At such curves, the parapet wall is provided only for safety of fast moving traffic.

What Is Hill Road?

The roads constructed in mountainous regions of a country are known as hill roads or ghat roads.
These roads present great difficulty in their alignment, design, construction and maintenance. Curves, sharp bends, sleep gradients and limited width of roadway make hill roads more liable to accidents. Also the effects of heavy rainfall on the construction and maintenance of a hill road are serious. At many locations on the hill roads, the land slides and slips may occur during heavy rainfall. Therefore, much care is needed during   their layout and construction so as to provide a stable and safe road. Moreover, a large number of streams cross the road and hence a suitable facility for cross drainage is needed.



The overall cost as well as cost per km length of a hill road is higher than that of a similar road in plains. The reason for this is that hill road construction involves difficult rock cutting, construction of more number drainage crossing and costly protective works like retaining walls, breast walls, parapet walls, drains, etc. which are specially needed for hill roads.

History Of Development Of Road Pavements In India

It is believed that the oldest mode of travel was on the footpaths later on, with the development of bullock carts and other simple animal drawn vehicles, roads were also developed. These early roads were constructed as kutcha roads, consisting of ordinary earth. The kutcha roads were soon deteriorated under heavy bullock cart traffic Thus metalled roads came into existence. The first indication of these roads in pre-historic period has been revealed by the excavations at Mohenjodaro and harappa (paklistan). It is believed that these towns were constructed 3500 years B.C. Earth and paved street pavements have been found in both of these unearthed towns.

the history of India does not reveal much about the different construction material used during different periods. However, the remains of the road in Rajgir ( Patna District ), constructed in 6th century B.C. i.e. during Aryan period and some archeological records show that the materials commonly used at that time for road construction were stones, mostlyin the undressed form. This material was used only for metalling the major roads whereas all other roads were constructed as ordinary earth roads. In towns, the road pavements used to be of undressed stone slabs.

With the development of techniques of modern road construction in England and many other countries, extensive development in metaled roads took place during British period in India. These roads were constructed on the basis of techniques suggested by Telford and Macadam in England.

Road Pavement

Water bound macadam (WBM) construction, based on Macadam technique, was commonly adopted. This method is now considered as one of the popular methods of construction road pavements. In this method, the brokenstones ofthe base and of wearing course, if any, are boundtogether by the stonedust in the poresence of moisture, WBM construction techniqueis still in use in our country both as a finished road pavements and also as ad good base coarse for superior road pavements.

With the developments of fast moving and pklneumatic tyred vehicles WBM road  pavements could not lost lost longer as they create dust nuisance during dry weather and became muddy during monsoon. In order to minimize dust nuisance, a thin coat of bituminous materials was tried with varying degrees of success.

Later on, it was experienced that thin  surface coating of bituminous materials was not sufficient to take the load of heavy commercial vehicles. So development of bituminous macadam pavements took place for better results, superior materials like bituminous concrete pavements were also developed.

The present trend of providing road pavements is to use cement concrete, plain as well as reinforced, for their construction. The cement concrete road pavements provide a good and an even riding surface They can be designed to take up the heaviest loads expected on the roads even in adverse soil and climatic conditions. Since concrete roads pavements involve heavy initial cost, therefore, they are not being extensively used in our country.

India is a developing country. There is,therefore, a dire necessity of a good network of roads in the country to keep pace with her developing plans.To meet this requirement, soil stabilized roads pavements have been developed so that maximum road length can be constructed at minimum cost. the present ordinary earth roads are also being improved by this method.

What Is Soil? Functions Of Soil Subgrade

The unconsolidated mineral material of earth crust is known as soil.
According to IS: 2809-1972, soil is defined as, "sediments or other unconsolidated accumulation of solid particles produced by the physical and chemical disintegration of rocks which may or may not contain organic matter.
The soil may also contain air, water, organic matter, consisting of more or less decomposed remains lof plants and animal organism and other substance which remain dispersed through out the mineral particles of the soil. Thus soil is non-homogeneous, porous and extremely variable in its composition as well as in properties.
Soil not only forms the foundation of  road pavements but also is the principal material used for their construction. Since there is a wide variation in soil types, an adequate knowledge of the properties of  different types of soil is, therefore, essential for proper design and construction of road pavements.

Soil Subgrade

The importance of soil as a highway subgrade lines in the fact that it act as an integral part of road pavement. the soil as a highway subgrade serves the following functions :-

1. To provide an adequate support to the road pavement.
2. To provide stability to the road pavement.
3. To provide good drainage of rain water percolating through the road pavement.

The various defects such as waves, corrugations, ruts, cracks, etc. occurring  in the road pavements are mainly due to poor subgrade soil conditions. the subgrade soil should, therfore, be well compacted and stabilized so as to prevent these defects and  to keep the road pavement stable and serviceable for a longer period.

What Is Traffic Engineering?

The phase of Highway Engineering which deals with planning and geometrical design of roads, streets, adjoining lands and with traffic operations there on for safe, convenient and economic transportation of persons and goods is known as Traffic Engineering.

Present day roads are to serve all types of traffic from pedestrian and animal driven traffic to automobile traffic including military vehicles and are thus liable to traffic congestion. So, to avoid traffic congestion and to provide efficient free and rapid flow of all types of traffic, the studies of traffic characteristics and traffic operations have become essential before planning and designing of any highway.

Now these aspects of planning and geometrical design of road and traffic studies have become so important that they constitute a separate branch of civil engineering, known as Traffic Engineering and the person who performs thes traffic studies is called traffic engineer.

Objects of Traffic Engineering :- 

1. To provide efficient flow of traffic.
2. To provide free flow of traffic.
3. To provide rapid flow of traffic.
4. To provide safety to the traffic.

Thus with different measures in Traffic Engineering safe, convenient and economic transportation of persons and goods can be achieved.

Scope of Traffic Engineering:-

Traffic Engineering includes the study of the following phases:-

1. Traffic characteristics
2. Traffic operations 
3. Traffic planning
4. Traffic geometrical design
5. traffic administration.

As per scope of this book we shall be studying about the details of only first two phases in the subsequent articles of this chapter.

Geometrical Design Of Highways

The phase of highway design which deals with the visible elements of different highways is called feometrical design of highways.

A proper geometrical design of a highway essential before its actual construction to provide speed, safety and comfort to the road users.

The following ideals should be kept in view while doing the geometrical design of a highway :-

1. There should be proper record of survey work done in the field.
2. There should be sufficient cross-sectional dimensions such as carriageways width, formation width, right-of-way, etc.
3. The road alignment should be economical.
4. There should be easy gradient.
5. There should be adequate camber  on straight portion of the road.
6. there should be proper superlevation on curved portion of the road.
7. There should be efficient drainage system.
8. There should be provision of proper curves.
9. There should be provision of extra roads width on curves.
10. There should be provision of sufficient sight distances available on curves.
11. There should be provision of *road signals, particularly at **road junctions.
12. Estimated cost of the project should also kept in view.

What Is Road Geometrics?

The physical features of a road are known as road geometrics.
These physical features have direct connection with the highway users. These are provided according to their      geometrical design in order to facilitate safe and economical of vehicles.

Road geometrics include the following elements of a highway :-

1. Cross-sectional elements such as right-of-way, road margins, formation width, carriage width, shoulders, side stopes, kerbs, formation level, camber, gradients, etc.
2. speed of road vehicles i.e design speed, average running speed, etc.
3. Sight distances such as stopping or non-passing sight distance, passing or overtaking sight distance, intermediate sight distance and lateral sight distance.
4. Curves such as horizontal and vertical curves.
5. Superelevation, etc.

Road geometrics are greatly influenced by the  topography of the area, traffic characteristics and the requirements of road users.

What Is Reinforced Cement Concrete ( R.C.C )?

Reinforced Cement Concrete ( R.C.C ) :-

Cement Concrete is quite good  in compressive strength but is very weak in tensile strength. so the use of plain cement concrete is restricted. In most of the cases, the members of a structure are subjected to bending    , shear and torsion stresses. Though the tensile strength of cement concrete is very low, yet it has been found that the use of cement concrete is possible in the construction of members which are subjected to high tensile strength. For ths purpose steel bars or steel reinforcement are put in the tensile zone of the member and then the concreting is done. the material thus obtained is called Reinforced Cement Concrete Or RCC, So in other words, R.C.C is the combination of cement concrete and steel bars.

What is Highway transportation? Importance of highway tranportaion

Highway transportation is the means of detail distribution between homes, shops, factories, e.t.c. It is only the roads which can carry goods from and to aerodromes, harbours and railway stations. Considering the utility of roads anywhere in the different parts of a country, they can be rightly compared to arteries 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.

Highway Transportaion

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

1. They facilitate conveyance of people, goods, raw-materials, manufactured articles, etc. speedily and easily in the different parts of a country. 
2. They act as the only source of communication in regions of high altitude i.e in mountainous regions.
3. They help in growth of trade and other economy activities in and outside the villages and towns by establishing contact between towns and villages.
4. They help in providing efficient distribution of agricultural products and natural resources all over the country.
5. They help in price stabilization of commodities due to mobility of products all over the country.
6. They help in social and cultural advancement of people and making the villagers active and alert members of the community.
7. They help in promoting the cultural and social ties among people living in different part of a country and thus strengthen the national unity.
8. They help in providing improved medical facilities quickly to human beings, especially to those who live in rural areas.
9. They provide more employment opportunities.
10. They enhance land value and thus bring better revenue.
11. They serve as feeders for Airways, Waterways and Railways.
12. They help in reducing distress among the people, caused due to famine, by supplying them food and clothing quickly.

Lastly, it can be sad that roads are the symbol of country's progress and thus development made by any country can be judged by the quality and network of it's road system.

What is Highway Surveys?

The various stages of examination of an area so as to locate the road finally in an economical manner are known as highway surveys.

Highway Surveys

The various surveys to be carried out for locating a highway are reconnaissance survey, preliminary surveys and location survey which shall be discussed in detail at a latter stage  in this chapter. In addition to these basic surveys, *soil survey is also included these days. These surveys are essentially conducted so as todecide the best location of the proposed road and to collect necessary data required in the preparation of highway plans and to design the road pavement.