A 33m-long overbridge outside Alipore zoo has been carrying hundreds of people every day, easing traffic in the area but raising fears about its load-bearing capacity.

Over the past three days, there have been several moments when a few hundred men, women and children have boarded the overbridge together, leading to chaos and a stampede-like situation, sometimes forcing police to close entry to the footbridge for some time.

Bridge expert Biswajit Shome, who was part of the construction team of the footbridge, said the portion of the structure that remains suspended over the road is capable of bearing the weight of 700 people with an average weight of 70kg each. “But ideally the load on the bridge at any given time should not reach saturation point,” Shome said.

Regulating the number of people using the bridge could prevent overloading.

The footbridge, that was opened 10 months ago to help pedestrians cross Alipore Road without affecting vehicular traffic in front of the zoo, hangs 6.5 metres above the ground.

“The structure has been designed and approved by engineers of Jadavpur University. We are confident about its durability,” said Kesto Saha, director of Karukrit, the company that built the overbridge in collaboration with the Calcutta Municipal Corporation.

The Christmas-New Year festive period draw tens of thousands of visitors to the zoo and that is when the bridge has to take a “practical load test”.

Pedestrian rush, including visitors to the zoo, had been a long-time traffic menace at the crossing till the footbridge was inaugurated.

The bridge has an escalator on either side to help pedestrians climb the structure. For going down, there is a flight of stairs at both ends of the bridge.

CCTV cameras have also been installed to maintain vigil on the crowd.

Volunteers and security personnel engaged by Karukrit have been managing the crowd on the overbridge.

Security personnel posted on the bridge admitted there have been moments when the crowd had swelled beyond their control.

“The biggest problem is many people are unable to use the escalator properly and keep tripping. Another problem is that some people are using the stairs to climb the bridge while they are meant for going down. That is creating congestion,” said one of the security personnel.

The police have also posted additional forces on the road below to manage the crowd flow in the channel leading to the footbridge. When the rush compels the police to bar entry to the bridge, barricades on the road are removed and pedestrians allowed to cross the road.

“There are three sergeants and 15 constables from the traffic department alone. This apart, there are teams from nearby police stations to manage law and order. We are trying our best to ensure that the traffic on the road and overhead is managed without disruption,” said a senior officer at Lalbazar.