A stretch of Diamond Harbour Road caved in barely 10m from the Hooghly in Diamond Harbour on Thursday morning, effectively cutting off a large part of South 24-Parganas from Calcutta and casting a cloud on weekend travel plans of many.

The road was sliced off like a cake, a sight more associated with calamities such as earthquake, near Jetty Ghat in the South 24-Parganas town, around 55km from Calcutta.

The yawning gap was at least 4m deep in some parts, said an official of the public works department, the custodian of the road, also referred to as National Highway 117.

The state government was trying to divert the vehicles from the city through the Usthi-Hatuganj Bypass. Officials in the district administration said the alternative road was not strong enough for heavy vehicles such as trucks and buses.

“We are trying to clear the bottlenecks on the alternative road within a couple of days so people living beyond Diamond Harbour don’t suffer,” a state government official said.

PWD officials said an ongoing beautification project could be the reason for the subsidence in the two-lane, 7m-wide road.

A PWD engineer who visited the site said it was too early to ascertain the reason for the damage. “It is still not clear why the subsidence took place. But use of heavy machineries, including earth movers, for the beautification project cannot be ruled out as a reason,” he said.

Engineers who visited the site said at least 4m of the width of the road had subsided.

“The remaining portion of the road cannot be cleared for traffic until the affected part is restored. We started repairs on Thursday afternoon but restoration might take at least 15 days,” an engineer said.

“We have to put up a strong structure, preferably of steel, along the river before the subsided portion is filled up. The stretch can be laid afresh only after that.”

A picture of the affected stretch downloaded from Facebook Telegraph picture

While some PWD officials are hopeful that the alternative route would be ready for all types of vehicles by the weekend, others doubt whether that is possible given the number of bottlenecks.

The damaged road leads Bakkhali and Fraserganj in South 24-Parganas. Both, along with Diamond Harbour, are popular weekend gateways.

The travel plans of thousands of Calcuttans have been thrown into uncertainty.

Weekend tour groups on Facebook were replete with posts and pictures of the cave-in. While most Netizens with weekend plans in Bakkhali were looking for alternative routes, some dwelt on the reasons for the cave-in.

“This road is the main embankment in Diamond Harbour. A beautification project, underway before the election, had drilled deep into the road. That weakened the base and and the road gave away after being hit by the Hooghly water,” a member of one such weekend tour group said.

PWD officials said the department had plans to strengthen the highway and widen it to four lanes till Namkhana, as part of its plan to upgrade connectivity to Sagar Islands.

“So far, work between Taratala and Joka has been taken up. A detailed project report is yet to be prepared for the rest. The subsidence could have been averted had the project been taken up earlier,” a PWD official said.

The PWD maintains two-lane national highways with the funds from the ministry of roads, transport and highways, and the National Highways Authority of India maintains four-lane roads.

“There is no dearth of funds to maintain the two-lane stretch of NH117. The road is maintained properly in most of the stretch. The subsidence did not take place because of lack of maintenance,” said an official.