A 600-metre stretch of the eastbound ramp of the AJC Bose Road flyover that connects it with the Parama flyover is in poor shape and will require an overhaul, said engineers of the Kolkata Metropolitan Development Authority (KMDA).
The existing bituminous surface will be scraped off and a fresh layer of bitumen will be laid.
Engineers said the surface has become so "distressed" that patchworks won't sustain for long.
Patchworks or temporary repairs were done on the stretch earlier, but the surface has yet again started to wear off. Cavities have formed on the surface and the ride has become bumpy.
A police officer said that the condition of the surface deteriorated rapidly over the past two weeks as rains intensified. If the road is not repaired quickly, potholes will develop after more rain, he said.
"The volume of cars that pass through the ramp is very high. There is a possibility that the surface would disintegrate further following more rain. That could lead to traffic snarls," said a police officer.
The 800-metre ramp was thrown open in 2019.
Since then a large number of cars and two-wheelers headed to EM Bypass, Salt Lake and other neighbouring areas from central Kolkata use this ramp that links to the Parama flyover.
Cars prefer the route since there are no traffic signals for nearly 6km starting from near the Victorian Memorial to EM Bypass. The time taken is many times less than the commute through the roads under.
A KMDA engineer said there has been a problem with the surface for a few months. Once the cracks developed, the friction caused by speeding cars moving over them widened the cracks.
"The road surface has become distressed. Patchworks will not help. We have to undertake a thorough repair. The top layer has to be removed and a fresh layer of bitumen will be laid," said another KMDA engineer.
The KMDA, which does not possess a road milling machine that removes the top bituminous layer, will write to the Kolkata Municipal Corporation (KMC) to hire one of its machines.
An official of the KMC said KMDA officials had spoken to them and a formal request will come soon.
"We have five road milling machines and one of them is for narrow lanes," said the official.
KMDA engineers said the entire repair — removing the top layer and laying a fresh layer — will take about 15 days. He said that they will apply for a night block on the ramp to go ahead with the work.
The surface of a few other stretches of the Parama flyover has also started to break, but the KMDA will undertake patch repairs in those stretches.