18 December,2014 06:41 AM IST | | Shashank Rao
The last suburban train on December 20 at both CST and Karjat/Kasara ends would start at 10.30 pm; authorities will then conduct test runs in the night on the CST-Thane stretch using the new 25,000-volt power supply
The British had considered upgrading the current supply of 1500-volt Direct Current (DC) to 25,000-volt Alternating Current (AC) an impossible task in their manuals, said Central Railway (CR) authorities.
The last regular train from CST and Karjat/Kasara end will be at 10.30 pm on Saturday. Normal services will resume only after 7.30 am on Sunday. File pic
On the night between December 20 and December 21, CR is doing just that. Authorities will carry out trial runs of local trains on 25,000-volt power supply between Chhatrapati Shivaji Terminus (CST) and Thane. This, however, will disrupt train services on Saturday night.
On Saturday night, CR will discontinue services at 10.30 pm from CST as well as from Karjat/Kasara end. All the existing fleet of trains will be parked at yards and sidings.
They will then begin work on carrying out this trial between CST and Thane. Officials said that they have already requested the BEST to run additional bus services to prevent inconvenience to commuters.
Transformation
While the sub-stations between CST and Thane charge to 25,000 volts, authorities will simultaneously prepare trains, including local EMUs, locomotives and other trains that can run on 25,000-volt AC section.
"We will be carrying out tests to verify if the new system on the CST-Thane stretch is ready for 25,000-volt AC. It will be for a period of at least eight hours," said Mukesh Nigam, Divisional Railway Manager (Mumbai), Central Railway.
At around 12 midnight, CR will run two trains that will be pulled by diesel locomotive, one each to Karjat and Kasara, in case any passengers are to be ferried home. The main trial runs will be between 2 am and 4 am, when different empty trains and locomotives will be operated at various speeds as part of the test.
The authorities expect to complete work by 7.30 am, after which supply will revert to 1,500-volt DC. The CST-Thane/Panvel routes are the only ones using this obsolete system.
"This is just a trial, so we will have to go back to the existing power supply system on this route. Even the first train in the morning hours will be operated using diesel locomotive," said a senior CR official.
The catch
The new system is meant to improve train workings, save R124 crore annually and improve speeds of trains; the last item, however, has a caveat. Sources said there are around 17 locations between Kurla and CST where speeds may be affected due to over bridges. "There are around eight locations where there is a height restriction of 4.27 meters between the track and the overhead wires.
At these locations, there are road and foot over bridges. So, we had to use double insulation," said a CR official. Under normal circumstances the advisable height is 4.42 meters. But CR have applied for special permissions at Masjid, Byculla, Currey Road, Matunga and Sion, where neither the height of bridges can be raised nor the track below can be lowered further.
"Our main fear is that those who are inspecting the safety parameters will put speed restrictions of around 15-20 kmph at these locations," said a CR official. This will significantly chop away any speed advantage the other sections may garner. However, the authorities are positive that the trial run will succeed. The authorities are also looking at removing at least nine old trains that are presently plying only on DC.
After the trial run, a detailed report would be sent to the Commissioner of Railway Safety, Lucknow, and the Railway Board in Delhi. It is after approvals from them that the new supply can be put to daily use.
