Hyderabad: Ever feel the average city road becoming mushy under your feet, or chunks of the metal coming off in the summer heat? That could be because some contractor has sneaked in lower grade bitumen to lay the road.
Problem is, the GHMC sinks hundreds of crores of rupees on roads does not know for sure if contractors are using the right grade of bitumen.
According to Dr P. Sravana, professor, transportation engineering, JNTU, bitumen is graded depending on its viscosity. “The grade of bitumen used depends on the maximum temperature of the region,” Dr Sravana said.
For Hyderabad, with its peak summer temperature in the mid-40s, roads must be laid with bitumen graded at VG-30 because it is harder. The bitumen to be used for Kashmir’s roads will be different from the one used in Telangana because of the temperature differential, she said.
Additionally, the new road should be kept undisturbed for 24 hours or stone dust should be spread on it so that the metal does not get stuck on vehicle tyres. “Bitumen pieces get into the vehicle because it has not hardened,” added the professor.
“The contractors should always use a grade of bitumen which has a softening point that is above the region’s maximum temperature,” said Prof. Laxma Rao of JNTU’s transportation engineering department. A test has to be done to identify the grade of bitumen has be used. He said Hyderabad needs a bitumen grade of VG 30, he said.
When contacted, GHMC chief engineer Suresh Kumar said the corporation in all its road tenders specifies 80/100 grade bitumen keeping in mind the ambient temperatures.
“The same grade of bitumen is specified for highways,” he said.
Prof. Sravana said the 80/100 grade also includes ductility, penetration level and grade of bitumen; VG-30 is more of an academic description.
“If the GHMC is specifying 80/100, that means all the three factors — penetration levels, ductility and softening level — are high, which is correct,” the professor said.
But then, the corporation’s quality control cell has to check and approve the quality of work for bills to be cleared.
In practice, approval is given without testing and the bills are cleared. Sources said the GHMC does not test the material used by the contractors; nor does it know what grade of bitumen is being used.
According to an RTI reply, the GHMC has spent Rs 715 crore on repairing and layering of roads and building footpaths. The corporation spent Rs 275 crore in 2013-14 and Rs 440 crore in 2014-15. The GHMC says that the cost of maintaining 1 km of roads is Rs 1 crore. As part of the 100-day plan, the GHMC is laying 569 black top roads at an estimated cost of Rs 333.01 crore.
As for leaving the surface of new roads untouched for 24 hours, a GHMC official said commuters use the busy roads round the clock. Road-laying is done at night because there is little traffic. He said most contractors spread stone dust after the road is laid.
