By Apurva Bhatt

After years of delay Central Railway's main line will switch to 25KV alternating current (AC) this weekend, as the commissioner of railway safety (CRS) has given the go-ahead but laid down speed restrictions to prevent any untoward incident. 

The switchover had been held up between CST-Thane due to lack of clearance from the CRS due to safety concerns and absence of rakes that can run on advanced traction power. 

CR general manager S K Sood said, "We will carry out the switch on Saturday night. Speed restrictions at some stretches will not impact punctuality of trains." It will be till 6am on Sunday. The CRS (Central Circle) Chetan Bakshi said, "On the slow corridor, the speed restriction is 85kmph, and on the fast corridor 90kmph. We have adequate AC compatible rakes to ensure no loss in service." The Siemens rakes can clock more than 100kmph. There are speed restrictions at nine stretches due to height restrictions (inadequate gap between OHE and roof of train, and OHE and base of road overbridges across tracks). At some places, the Siemens rakes will not exceed 15kmph. 

The CRS said the height from the base of the FOB/ROB should be 250mm from the OHE wires, and similar clearance is required between OHE wires and train rooftops. With the Siemens rakes, clearance available is only 190mm, as against 250mm. The clearance level is slightly better at 200mm but not adequate. 

Sood said, "The CRS has pointed out issues with the gradient of the OHE, but this will be rectified over three to four months." 

The speed restrictions will be relaxed after the monsoon. CR undertook test-charging of the AC power in December 2014. Part of the railway network, from LTT-Thane till Kalyan and beyond, has been converted from DC to AC.