The classification of roads in civil engineering is based on different factors like construction materials, rigidity, economic, traffic type, Location and function, Topography, etc. Here, I have described all one by one.
The road is a pathway with a smoothed or paved surface used for transportation purposes to reach from one place to another. Road transportation is the oldest means of transportation which has been proved as the most reliable and cheapest for people.
Components of Road
The different components of the road are:
- Carriageway: It is of two categories- double lane and single lane.
- Shoulder: It is the emergency path located at the side of the carriageway where a vehicle can stop at any time.
- Margin: It is the component of the road provided after the shoulder which helps to drain water.
- Median: It is the component of road that is provided between the opposing road traffic way.
- Roadway: It is the length of the road from one shoulder to another shoulder. It consists of the carriageway, median, and shoulder.
- Right of way: It is the whole length of the road from one margin to another margin. It consists of margin, shoulder, carriageway, and median.
- Kerb: It is provided along the median and painted black and white consecutively.
- Guard Rail: It is provided to support the vehicles from the accident and mainly built in hilly areas.
- Building line: It is the distance from the center of the carriageway to building sites or petrol pumps or some other places. The building line differs from country to country. In Japan, the 7m building line is maintained and in the USA the 5m building line is maintained. It is maintained so that buildings are not disturbed by the vehicles.
Classification of roads in civil engineering
The Classification of Roads into various categories based on different factors are given below.
1) Construction material used
Earthen roads are laid with soil and are cheaper for all types of road. This type of road is provided for less traffic areas and or for countryside areas. Good drainage should be provided so that the lifespan of the road will be longer.
They are also low-quality roads but better in comparison with earthen roads. A compacted mixture of gravel and soil is used as pavement material in this case.
Murrum is a substance obtained from the disintegration of Igneous rock by weathering agencies. The roads made from murrum is known as murrum roads.
Kankar is the impure form of limestone. Where limestone is available in good quantity this type of roads is made. These type of road is also of low quality and has similar usage as of murrum and gravel roads.
Water Bound Macadam (WBM)
As the base course of WBM roads crushed stone aggregate is used. The aggregates are spread on the surface and water is sprinkled before rolling. WBM roads have better performance in comparison to other types of roads.
WBM roads are laid as layers. Each layer is about 10 cm in thickness. They may disintegrate immediately under traffic as they are very rough.
Bituminous roads are very popular and most used roads around the world. They are flexible and their thickness depends upon the subgrade soil conditions. They are low-cost roads and are good for driving conditions.
Cement concrete roads
Cement concrete is used in the construction of pavements in case of concrete roads. These are very popular and costlier in comparison with all other types of roads.
They require less maintenance as they are not flexible. They are suitable for high traffic areas. They are laid with joints and their time of construction is more.
2) Location and function
National highways are the main roads of a particular country and connect all major cities to the capital city of the country. They run throughout the country. National highways are provided with a minimum of a two-lane road.
State highways are the second main roads connecting major parts of the state within it. They ultimately connect to the national highways.
District roads are that type of roads which connects markets and production places located in the cities to state and national highways. There are namely two types of district roads: Major district roads and Minor district roads.
Major district roads help to connect the headquarters of the neighbouring district with main parts of the district. Minor district roads are laid within the district.
Rural roads or Village roads
Rural roads connect the nearby villages and lead to a nearby town or district roads. Generally, rural roads are low-quality roads because there is low traffic in village areas.
Low cost roads
Low cost roads require less capital and can be constructed using locally available materials. This type of roads is constructed in villages where traffic is low.
Medium cost roads
Medium cost roads require capital more than low-cost roads and help to travel from the village to nearby towns. They are generally made up of bitumen.
High cost roads
High cost roads require huge capital. They are generally made up of bitumen and cement concrete. National highways and state highways are an example of high cost roads.
Pedestrian ways are made for pedestrians and no vehicles are allowed to enter in this way.
Cycle tracks are provided on both sides of the pavement for the cyclist so that they can travel safely.
Motorways, also known as expressways are accessible to only a few types of vehicles for use. The vehicles that can move with high acceleration are allowed to move in this way. They provide comfort for high-speed vehicles and makes travel quick and easy.
Flexible roads are that type of road which contains flexible layer as pavement surface which requires good maintenance. Otherwise, they can be disintegrated easily with heavy traffic. All types of roads except concrete roads come under this type.
Rigid roads are non-flexible roads. Cement concrete roads come under this type.
Plain area roads
Plain area roads are roads that are constructed on a levelled surface.
Hilly area roads
Hilly area roads are roads constructed in hilly areas. They are also called ghat roads. The shape of hilly area roads is spiral.
6) Traffic volume
Light traffic roads
Light traffic roads are roads which can carry 400 vehicles per day on an average.
Medium traffic roads
Medium traffic roads are roads which can carry 400 to 1000 vehicles per day.
High traffic roads
High traffic roads are that type of roads which can carry more than 1000 vehicles per day.
I hope this article on “Classification of roads in civil engineering” remains helpful for you.
Happy Learning – Civil Concept
Civil Engineer – Sushmita Niraula