Metro Railways : BALLAST LESS TRACK
Client : Metro Railways, Calcutta
Contractor : CICO
Works performed from February to November
1987.
STRENGTHENING OF TRACK BED
The ballast less track of Metro Railways
Calcutta is basically rails laid over R.C. concrete bed by means of bearing plate and
rubber pads.
The track bed known as second pour or
levelling pour concrete was laid on the raft of the box of the Tunnel at a later date.
When track was opened for service, it was noticed that with the increase in traffic
density and speed above 50 kmph, the track was sinking in certain stretches of about 500 m
in length, between Kalighat and Jatin Das Park Station.
Thorough investigations were made and found
that there was a fine gap due to separation between the raft and second pour concreting.
The underside of the track bed was being pulverised due to constant hammering action of
the wheels and thus the track was sinking.
Metro Railways decided not to suspend the
traffic for strengthening the track, but to execute the work during the daily maintenance
period which was between 00.00hrs. and 0.5.00 hrs.
So their requirements were as follows :
Material
should be injectable
- Should have low
viscosity and free slowing properties.
- Should set and gain
compressive strength of at least 250 kg/cm2 within four hours.
Experimenting with various
materials the Railways authorities selected CICO EPOXCRETE 2:1 and CICO EPOXYCRETE epoxy
based grouts 2:1:2 which satisfied all the requirements.
Resicrete 2:1 & 1:2 were injected and the
result was found to be excellent by Metro Authorities. The CICO Group has been further
entrusted the restrengthening of -23 KM of the track beds. |
