The Times of India             19.08.2013

Corporation to adopt new norms for road laying

CHENNAI: Bogged down by complaints of roads getting damaged within a year of being relaid, Corporation of Chennai has decided to adopt guidelines on road laying framed by the ministry of surface road transport.

Roads under mega city mission 3 in the extended areas will be laid only after the soil strength is tested. The new guidelines will also hold the contractor responsible for maintaining the roads three to five years after it is laid.

"We intend to make the new roads qualitatively at par with roads in other metros," said a senior corporation official. "The ministry of surface transport has come out with a detailed prescription on road thickness, compaction and proportions for the bitumen mixture for different types of soil and its load bearing capacities," said the official.

Four types of soil are found within city limits - sand, clay, silt and silt clay. To test the strength of soil, a method called the California Bearing Ratio (CBR) will be used. CBR is a penetration test which will evaluate the strength of the soil under the road. The test is done by measuring the pressure required to penetrate a soil sample with a plunger, made of California limestone, of standard area.

According to officials, the system of arriving at specifications to lay a road had no thumb rule. "Engineers don't following any uniform method to arrive at the specifications," said a senior engineer at the corporation. "Road thickness, bitumen concentration, compaction, heating, gravel constituency were decided by a former corporation engineer based on his estimation," he added.

The civic body believes that once a scientific approach, like the one specified in the guidelines, is adopted to lay a road it will last for five years. Taking a leaf out of highways department and municipal corporations in Kerala, the corporation hopes to ensure contractors follow guidelines and take the responsibility of maintaining a road for at least three years.

"We are planning to specify in the tenders that contractors will have to maintain it or forego the percentage of their payment we hold back," said the official. At present, contractors maintain roads only for a year failing which 2% of their payment is held back.