Thane-Kopri bridge collapse: report blames segment-wise construction

The report of the Chief Commissioner of Railway Safety on the girder collapse at the site of a bridge under construction in Thane-Kopri last October has blamed the inability of the railway administration,the contractor and the consultant,RITES,to foresee that the wooden blocks supporting the girders could give way during prolonged duration of construction.

The girders had collapsed on a train,killing three and injuring a dozen. The report submitted by Sudhir Kumar,Chief Commissioner of Railway Safety,fixes primary responsibility on adoption of segment-wise construction,rather than building the bridge in one piece. The wooden blocks supporting the girders decomposed after bearing the immense weight for two years and failed to withstand the burden under the vibrations of heavy traffic in the suburban section,the report states.

Interestingly,contractor Deepak Mangal had reminded the consultant and the railway authorities of the hazards of placing the girders for long periods on trussing and wooden blocks. Why the railway authorities or the RITES did not pay heed to heed to the contractor’s warning has not been dealt by the Chief Commissioner of Railway Safety.

The report recommends studying and adopting bridge construction methods in China where train traffic beneath a construction activity is not affected. The report suggests the use of steel box and neoprene rubber instead of wooden blocks to support the girders (till it is lowered onto the bearings). Co-ordination meetings of senior officers of various agencies periodically to sort out various issues have also been suggested in the report.  

According to CR sources,work on the Thane-Kopri bridge over the railway tracks commenced in 2003 and was to be completed in 18 months. Even at the time of the collapse on October 23,2009,six years after work commenced,less than 50 per cent of the work had been completed. As per railway’s own admission,two months before the collapse,merely 56 hours of blocks (stoppage of trains to allow construction) had been allotted in six years. Each block lasted an hour from 1.40 am to 2.40 am.

“Moreover,in 2003,the then chief bridge engineer had removed the supporting columns thereby making the design complicated. With the columns in place,the girders were to be constructed in two segments of 12 metres and 28.25 metres,which was easier to move and place than the 43-metre-long girder weighing 132 tonnes.” sources claimed.

The REPORT

The cause: “I have arrived at the conclusion that the derailment of K-37 Dn suburban local due to collapse of 40 M concrete girder of under construction ROB of TMC between Mulund and Thane stations at Km 31/14 on electrified broad gauge double line of Mumbai-CST-Kalyan section of Mumbai division of central railway at about 10.45 hrs opn 23.10.2009 is due to wooden blocks supporting PSC girders for prolonged duration failure of under vibrations due to heavy traffic density in suburban section.”