As the much hailed mastic asphalt mixture, which was laid on the Pamban Road bridge, turned out to be ‘slippery’ instead of smooth as expected, the National Highway (NH) authorities have decided to replace it with bituminous concrete (BC) layer.
The NH laid the mastic asphalt surface with much fanfare in April on the bridge connecting the mainland with Rameswaram island claiming that the surface with the mixture of bitumen, lime, quarry dust and chips would make driving smooth.
The work was carried out at a cost of about ₹1,10 crore. Thereafter, the bridge witnessed frequent accidents with excess bitumen melting away and motorists experienced skidding. Officials blamed it on over-speed and overtaking but complaints continued to pour in.
After the Chief Engineer of NH inspected the bridge a few days ago, the authorities have decided to replace the surface with BC with less bitumen, sources said. The mastic asphalt surface was laid with 15% bitumen, 30% each of lime and quarry dust and 25% of chips.
Pending estimate clearance by the National Highways Authority of India (NHAI), the State NH on Tuesday began removing the mastic asphalt surface on the middle of the bridge, which served as a navigational span and started replacing it with BC. The mastic asphalt surface for 300 metres on the navigational span area was being removed and the relaying work would be completed in four or five days.
After NHAI cleared the estimate, the entire 2.345 km long bridge would have BC layer. The regional officer of NHAI in Chennai had sent the estimate proposal to NHAI in Delhi, sources also said.
The National Highway had opted for mastic asphalt materials to avoid increasing the weight but it turned out to be a failure.
Because the materials required 24 hours for setting after the surface was laid but they could not stop or regulate the traffic for that long. Parking of vehicles by tourists and pilgrims at the central portion added to the problem, they said.