It is highly important for roads, irrespective of their classifications, to be in good shape to aid the movement of people and transportation of goods. Putting roads in the proper shape is achieved through construction and maintenance. Roads are classified based on factors like locations, materials and traffic.

Classification of Road Based on Materials

• Earthen roads
• Gravel roads
• Murrum roads
• Kankar roads
• WBM roads
• Bituminous roads
• Concrete roads

Classification of Road Based on Traffic

• Light traffic roads
• Medium traffic roads
• High traffic roads

Classification of Road Based on Traffic Type

• Pedestrian ways
• Motorways
• Cycle tracks

Bituminous Roads

Bituminous road is the most popular and most used road in the world. It is low in cost and suitable for driving. The surface of bituminous road has bituminous materials which is also referred to as asphalt. It is a sticky dark viscous liquid obtained from natural deposits like crude petroleum. The thickness of a bituminous road largely depends on the subgrade soil conditions.

Types of Bituminous Surfaces

• Prime Coat

This coat has low viscosity bituminous binder and is applied to existing untreated pervious layer like WBM to improve the adhesion between base and bituminous surface.

• Tack Coat

It is also a single coat of low viscosity bituminous binder. It is applied between treated base and bituminous surface to improve the adequate bond between existing impervious base and wearing surface.

• Seal Coat

This is the final coat of bituminous material. It is applied on the top of surface in order to prevent the entry of moisture through the voids.

• Surface Dressing

This is the application of two or more coats of bituminous materials to prepared base. It consists of bituminous binders sprayed on which chipped aggregates are properly rolled.

Basic Procedure of Bituminous Road Construction

Bituminous road is flexible, smooth and allows for comfortable ride. The procedure of constructing bituminous road involves several steps ranging from preparation of surface, application of coats, preparation and placing of premix, rolling to quality control and finishing.

• Preparation of existing surface
• Application of tuck coat
• Placing
• Rolling
• Quality control
• Surface finishing and opening to traffic