Bamboo stairway to peril - Rickety jetties put thousands at risk on Bengal's waterfront every day

The bamboo-and-saal Barrackpore jetty during low tide on Thursday morning and (below) the state of the same jetty three hours later after high tide swept in. As the water level rises, the boats move closer to the bank. Pictures by Pradip Sanyal 

Kinsuk Basu,TT, Calcutta, April 27: For Roshni Srivastava, a young mother living less than 30km from Calcutta, the shortest route to her son's school demands a precarious perch on a jetty that wobbles with every wave that splashes by.

The jetty is made of bamboo and wooden stilts - similar to the one that collapsed in Bhadreswar yesterday. The confirmed death toll in Bhadreswar rose to six today and at least 17 people are listed as missing after a second day of futile search.

Between the Millennium Park jetty in Calcutta and Chandernagore in Hooghly, over half of the 54 jetties are temporary structures. Tens of thousands of people rely on the rickety jetties for their daily commute across the Hooghly river.

Standing on the edge of the swaying Barrackpore jetty, Roshni, who was taking her son Ayush back from Assembly of Christ School to their home in Serampore across the river, said: "Even if the jetty is weak, there is hardly any alternative for us."

"This is the shortest route to reach his school," she added. By road, the distance between Serampore and Barrackpore is around 35km via Vivekananda Bridge. The travel time is over two hours in the best traffic conditions. The Rs-5 boat ride from Serampore is a 10-minute affair.

Cantonment town Barrackpore has several missionary schools and many from across the river send their children to this side to study.

The jetty at Dhobi Ghat in Barrackpore that many mothers like Roshni use was today identified as one of the "most dangerous" by a government team that was formed following the Bhadreswar tragedy. (A joint inspection by transport officials and the district police this afternoon revealed that at least 25 jetties on the particular stretch are in a bad shape.)

This afternoon, as a tidal bore ( baan or a large wave caused by the constriction of the tide as it enters a narrower and shallower stretch) hit the Barrackpore jetty, the whole structure wobbled.

The jetty operators ran to the shore. " Jaben na, jaben na, baan aaschhe (don't go, don't go, a tidal bore is coming)," someone yelled.

Which was a vast improvement. Usually, commuters are supposed to read the mood of the Hooghly river by the presence or absence of other humans. "It is left to us to gauge by the sight of an unmanned entry point that venturing to the river then was unsafe," a boat passenger said.

After the Bhadreswar tragedy, no one was taking chances. Hence, the warning that was shouted out.

Between the two ghats, around 10,000 passengers cross this part of the Hooghly on mechanised country boats (bhut-bhuties) every day.

Across the river is Serampore. It has a pontoon jetty made of steel since 1997. A sturdy pontoon jetty, which goes up and down in sync with the tides, costs between Rs 3 crore and Rs 4 crore. Besides a fresh coat of paint and regular oiling of the bolts, the steel sheets below and on top need to be changed every few years.

Specific figures for the bamboo jetties were not available but the consensus is they are much cheaper. The annual maintenance of the bamboo jetties is said to cost around Rs 12 lakh. The poles are vulnerable to worms and their iron supports get twisted by the tidal waves.

Some of the partners of the agency that now runs the Barrackpore jetty, Jugal Auddy Ferry Service, said they had "years of experience" in running the facility.

No one knows whether any engineering calculation was involved when these structures were rigged up. Structural engineers said several calculations should be taken into account when a structure is built on a riverbed. Factors such as the nature of tidal bore, the depth, the footfall of passengers and the volume of goods being transported are all relevant.

"When a tide hits a wooden log, it creates a horse-shoe vortex which scoops out sediments and scours a hole at the base of the stilts. This poses a serious threat to a structure.

Many bridges have collapsed because of scour holes. So, one has to be very particular with calculations while building a jetty," said Kaustav Debnath, a researcher in river engineering at the Indian Institute of Engineering Science and Technology, Shibpur.

"There have been advanced studies on the tidal characters across Indian rivers. But the findings have not been reflected in the design code, which has been drawn up for constructing jetties," he added.

"Even for temporary structures there are certain calculations. The foundation of the structure has to start well below the scour depth so that it can withstand the pressure of high-tides," said Partha Pratim Biswas of the department of construction engineering, Jadavpur University.