Apart from planning pathways for pedestrians and open spaces, the elaborate planning for the Brihanmumbai Municipal Corporation’s ambitious Coastal Road project will include advanced ventilation and fire safety systems to be installed in the tunnel. As part of the safety measures, the BMC is planning to take up measures to ensure that there are minimal casualties in case of a disaster like a fire or structural collapse.
The tunnel is one of three sections of the South phase, which starts from the Princess Street flyover till the Worli sea link, a stretch of 9.98km, and will help decongest traffic at Haji Ali junction, Pedder Road and Breach Candy. Taking a cue from the system used in tunnels in other countries, the BMC is planning to install a structural fire protection system in the tunnel.
Civic officials pointed out that in most cases of fires which break out in tunnels, more people die due to suffocation and inhalation of carbon monoxide. In case a fire breaks out, this system will act as an emergency escape for the people travelling through the tunnel. “We are going to install state of the art ventilation and fire fighting system and will make sure that the safety of the public is not compromised with in any way. We will incorporate the structural fire protection system in the existing plan of the tunnel and will ensure that people have a pleasant driving experience,” said Sanjay Mukherjee, additional municipal commissioner.
He added that the dimensions of the safety room will be decided at a later stage depending on the traffic flow though the tunnel. Termed as the alternate fire and life safety system, the tunnel will have an in-built passage where people can be moved into until the fire is under control and the fire brigade is able to rescue them. Apart from the safety room, enhanced fire fighting systems will be installed in the tunnel which will include a dual redundancy twin loop pressurized fire main system instead of the conventional tunnel fire main.
As part of the tunnel ventilation, the BMC is planning to install the Saccardo nozzle based system instead of the existing jet fan based system. “The old tunnels have jet fan systems and apart from being high maintenance, they are not as effective as the nozzle based system. In this system, the fans are not affected in the event of a fire,” said additional municipal commissioner Sanjay Mukherjee.
A study conducted on the jet fan based system also revealed that the design life of the fans is less than 15 years owing to the corrosive environment of a road tunnel. Mukherjee added that these jet fans create a turbulent air flow and are not effective for controlling smoke. Among other benefits, the nozzle system will also have minimal disruption during maintenance work and traffic will not have to be diverted.
As part of the revised plan of the project to bypass long-standing delays in acquiring environmental clearances, the 29.20 km long bridge was divided into two parts. While the South phase, which includes the tunnel, runs from the Princess Street flyover till the South end of the Bandra-Worli Sea Link, the North phase will cover the stretch from the North end of the Bandra Worli Sea Link till Kandivali.