The Delhi Metro Rail Corporation (DMRC) will build over 100 cross passages between parallel underground tunnels in its upcoming Phase 3 to allow people to move from one tunnel to the other on foot in case of any emergency like fire, metro officials said.
“The Delhi Metro has a network of cross passages in their underground sections which connect the two parallel underground tunnels. Two Metro tunnels are generally built parallel to each other for up and down movement of trains and these cross passages allow people to move from one tunnel to the other on foot in case of any emergency like fire or any other unusual occurrence in either of the tunnels. These walkways can be used for carrying out maintenance work also,” DMRC said.
A cross passage is generally a small path between two tunnels connected through a walkway varying between 6-10 mettres.
“There will be a cross passage after approximately every 240 mtrs inside every underground tunnel. Cross-passages are built with reinforced concrete. They are provided to serve two primary purposes: emergency escape and maintenance work,” Metro officials said.
In the existing network of the Delhi Metro, there are already a total of 108 cross passages which protected with fire door assemblies and have a fire protection rating of 1-1/2 hours with a self-closing fire door.
“The construction of cross-passages is very challenging as workers have to do a lot of manual work in confined spaces and diligence is required by the supporting engineering staff to monitor the excavation and movement of ground. Over 50 kms of Phase III construction of the Delhi Metro involves underground tunneling,” officials added.