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Centre brings uniformity in smoothness of national highways, Infra News, ET Infra


Centre brings uniformity in smoothness of national highways

The Ministry of Road Transport and Highways has defined stricter and uniform parameters to dictate smoothness of Indian highways. To bring this into effect, the model request for proposal (RFP) and agreement documents for all forms of contracts, which are signed to make highway projects, have been amended to incorporate a desirable and acceptable roughness for both flexible and rigid pavements.

A pavement is the top most layer of the road which is used to transmit loads to the sub-base and underlying soil. A smoother pavement improves ride quality for commuters on roads.

Roughness of a road is measured in millimetres per kilometre (mm/km) a lower value means smoother driving experience. It has been decided that roughness for a flexible pavement road is desirable at 2000 mm/km and acceptable to 2400 mm/km. For a rigid pavement road, the desirable roughness has been fixed at 2200 mm/km and acceptable is 2400 mm/km.

Speaking to ET, Ajai Kumar Singh, Professor, Department of Civil Engineering at Motilal Nehru National Institute of Technology said that the effect of roughness is more applicable to the design speed of a road. “For higher class of roads like expressways and highways, with a design maximum speed of 100-120 kilometres per hour (km/hr), roughness parameters have to be more stringent.”

According to Singh, the rigid pavement is used in expressways while flexible pavement is used for rural roads. “A lower value of roughness will demand higher value of construction,” he added.

Largely at par

Commenting on the parameters that have been fixed, Kayitha Ravinder, Chief Scientist at Transportation Planning and Environment Division of Central Road Research Institute (CRRI) said, “The roughness values that have been fixed are near to the usual contract and is also at par with international standards…It will affect the cost of construction and maintenance of highways.”

According to Ravinder, the international standard for roughness is 2000 mm/km. “If it is beyond 2500 – 3000 mm/km, the vehicle will oscillate and vibrations will grow. Older roads need to go for overlay to maintain lower levels of roughness,” he said adding that at 2000 mm/km roughness, the permissible maximum speed of a vehicle can go up 120 kilometres per hour. Beyond 3000 mm/km, the speed needs to reduce to 40-50 km/hr and tire wear will be more.

The amendment covers future roads built under the engineering, procurement and construction (EPC), build, operate, transfer (BOT), Hybrid Annuity Model (HAM), and Toll Operate Transfer (ToT) agreements with road developers.


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