More than five years after deciding to demolish five road overbridges (ROBs) between Dadar and Chhatrapati Shivaji Terminus (CST),the Central Railway (CR) has come up with a technical solution that could help avoid razing of these busy bridges. The CR had decided to demolish the ROBs to raise their height in keeping with the requirements as the traction along the railway section was changed from direct current (DC) alternate current (AC). The new solution involves providing insulation to the high-voltage catenary overhead line. During the conversion of the section from Vangani to Kalyan from DC to AC,the CR had effectively tried this method at the Patri bridge between Kalyan and Thakurli. After the successful testing,we decided it could be implemented in Mumbai as well, said Vidyadhar Malegaonkar,chief spokesperson,CR. The overhead equipment (OHE) consists of a catenary,droppers and the contact wire. These set of parallel wires are connected between the two poles that hold it. The contact wire provides current to the EMU through a pentograph. According to a senior CR official,it has been decided to insulate the portion of the catenary that runs under these bridges and also raise the main catenary to the height of the bridge and connect it to the base of the bridge. While the insulation will ensure that the ROB is protected,the contact wire remains at the same height,but the required gap between the bridge and the contact wire is thus achieved. So,one one hand we are providing insulation to the catenary and raising it to the level of the ROBs surface,we are also maintaining a standard gap between the ROB and the contact wire, the official added. Under Phase II of the MUTP,the conversion of traction from 1,500 volts DC to 25,000 volts AC necessitated demolition of ROBs. For a ROB,the separation from the live wire below has to be around 5.5 metres even when the traction is DC,but is currently around 4.7 metres at most bridges. For an FOB,the gap from the OHE should be around 6.25 metres. The step would also save CR some money. The initial cost of demolishing and rebuilding the bridges was Rs 64 crore. The CR revised the list and added a few more bridges to be demolished and the cost spiralled to Rs 360 crore. One of the reasons behind this decision was addition of more bridges that were to be demolished. If these bridges were to be demolished,the deadline would have exceeded. Plus,the Brihanmumbai Municipal Corporation (BMC) and the traffic police would have not allowed us to demolish all these bridges at the same time, the official added. CR officials,however,pointed out that though the decision to raze the bridges has been put on hold,they are likely to go ahead with the demolition of Hancock bridge near Sandhurst Road. The tenders have almost been finalised,permission from the BMC and the traffic police sought and more importantly,even in the existing conditions (the DC traction) trains have to follow a restricted speed limit along this stretch. The Western Railway (WR),too,has decided to go ahead with the demolition of Carol bridge,connecting Parel and Elphinstone Road station.
