4 Types of Low Cost Road (Cheap Road) : Construction, Advantages & Disadvantages

The road that is constructed and maintained at a low cost by utilizing the locally available materials & labor is a low cost road.

It is also referred to as a cheap road.

In the villages and underdeveloped areas; the immediate need for roads can be fulfilled at a low cost by these roads and can be improved further if required in the future. 

Features:

  1. Types of Low-Cost Road  

There are four types of low-cost roads:

a. Earth Road 

The type of low-cost road in which pavement structure is constructed with the soil available at the site is called earth road.

✔ It is also known as the earthen road.

Fig: Earth Road

How many types of earth roads are there?

There are 2 types of earth roads named Ordinary Earth Road & Stabilized Earth Road.

i. Ordinary Earth Road  

The earth road whose foundation and the wearing surface are made up of one or two compacted layers of natural soil along its alignment is an ordinary earth road.

It is the first stage of road construction.

Features: 

a. It requires frequent maintenance. Mainly in the rainy season.

b. It is dusty and ruts are formed quickly.

c. It is not suitable for very heavy vehicle movement.

d. It is very economical to construct.

ii. Stabilized Earth Road  

The road whose foundation and the wearing surface are made up of one or two compacted layers of stabilized soil is called stabilized earth road.

Stabilized earth road is capable of withstanding high load and traffic as compared to ordinary.

It is more durable than ordinary earth road.

Features: 

a. It doesn’t require frequent maintenance like ordinary earth road.

b. Initial construction cost is more as compared to the ordinary earthen road.

Note:

Stabilized Soil: Soil stabilized with physical, chemical, or biological agents to increase strength and durability

b. Kankar Road 

Fig: Kankar Road

Kankar road is constructed utilizing kankar (or chips of impure limestone) as the chief material. It is only constructed when limestones are available in sufficient quantity.

c. WBM Road 

Fig: WBM Road

WBM road is the pavement whose surface course is made up of crushed or broken aggregates that are mechanically interlocked by rolling and voids are filled using filler materials with the assistance of water.

✔ WBM road produces dust while providing service.

✔ Powder of Calcium Chloride or Bituminous Materials can be spread on the surface of the road to minimize dust.

✔ This road is not suitable for fast-moving vehicles.

✔ It is suitable for iron wheeled vehicles like tongas, bullock carts, etc.

✔ In many villages and rural areas;  WBM road is constructed initially and further improved or paved when the fund is available.

What does WBM stands for?

WBM stands for Water Bound Macadam.

d. Gravel Road 

Fig: Gravel Road

A gravel road is a type of unpaved road that is surfaced with gravel that has been brought to the site from a quarry or stream bed.

This road is common in less developed nations, and also in rural areas of developed nations.

  2. Construction of Low Cost Road  

The construction of low-cost roads includes the following steps:

a. Alignment Selection

The alignment shows the path through which the road will pass. So, the selection of road alignment should be done such that it has less conflict, high soil strength & shorter length.

Road alignment is the key factor that directly influences the construction speed and economy.

b. Cutting & Filling of Earth

Cutting and filling work is carried out to provide proper shape to the road.

During this process, if the side slope is unstabilized then retaining walls of wooden logs (or bamboos) are provided. In the absence of wooden logs; locally available stones are used.

c. Preparation of Sub-grade

Sub-grade preparation involves the process of compaction of the soil to increase strength, stability, and bearing capacity.

Compaction of sub-grade should be done with the assistance of water.

Road strength is determined by sub-grade. So, the subgrade should be compacted multiple times (according to the type of soil).

d. Preparation of Pavement Layer

Above the subgrade, a layer of material is provided which acts as both base and surface course.

On earth road, there is no pavement layer as the subgrade itself acts as the pavement layer.

The pavement layer is also compacted similar to sub-grade with the assistance of water.

f. Drying

The road is allowed to dry naturally for 1 to 3 days and then opened to traffic.

  3. Considerations in Low Cost Road  

1. The road shall be constructed on a balanced approach following the mass curve.

2. The road shall be constructed in stages.

3. Local materials shall be used.

4. Local manpower should be utilized.

5. Planning shall be done in a decentralized manner.

6. Bio-engineering shall be practiced for slope stability  (instead of costlier structure).

7. Cross slope of the road shall be towards the outside. So, as to avoid the side-drain.

8. In the case of natural water resources; a causeway shall be preferred instead of bridges, culverts, or other costlier construction.

9. The garbage wall and wooden log wall shall be preferred instead of the retaining wall.

  4. Advantages of Low Cost Road  

Some of the advantages of the low-cost road are:

1. No large investment of capital is required initially.

2. Local people and materials are utilized.

3. As bio-engineering is preferred for slope protection. It is more environment-friendly.

4. Stage construction technique helps to manage the dispute that arises at the construction site.

5. The cost of side drain construction can be saved.

6. It helps to mobilize rural materials.

7. It can be upgraded to the blacktopped road when required.

Some disadvantages of the low-cost road are:

a. Not suitable for heavy traffic.

b. The requirement of maintenance after heavy rainfall.

c. Low comfort & high vehicle operation cost.

Dream Civil Team

Educational Platform Under Naba Buddha Institute