METRO RAILWAYS : WATERPROOFING
CLIENT : Metro Railways, Calcutta
Contractor : CICO
Work Performed : 1984-85
STOPPAGE OF HEAVY INGRESS OF WATER

During the post-construction period, the Southern part of 'Calcutta Metro Railways' had a serious problem of inflow of water in the box tunnels through different locations which even effected the running of Metro Coach.
The sources of water ingress were :

Subsoil Water
Water flowing from old, dilapidated water mains and sewage of the city vicinity of the outer side of Box tunnels of Metro Railways, alignment from Esplanade to Tollyganj.
The leakage points were mainly :
a) Construction joints
b) Expansion joints
c) Joints between the entry structure and main box.
d) The area surrounding the embedded inserts (the end pieces of RSJ used as struts and double 'H' piles used as columns during construction period).
e) The periphery of the openings kept over the roofs slab at a distance of 1 km apart to facilitate the lowering of 13m long rails and other tracks fittings, which were subsequently covered with RCC slab and concrete and then back filled.
f) A large opening provided for lowering the coaches through the openings was subsequently sealed with RCC slab and concrete and back filled.

SELECTION OF BOX WALL

ELEVATION OF BOX WALL