In and around 2010 four Laning of Mankoli Vasai road was being executed and an additional bridge had to be constructed at Kharbav creek of 2 spans of 50 meters each with abutments on either side. It was design and construction contract with PWD as main client. While the first span was executed with a central support at 25 meters with piles and steel trusses the second span had an issue as there were fishermen who had to be losing their livelihood if the middle support would be taken. Client asked to us see if we could cast the bridge on a truss spanning entire creek bay of 50 meters. While that was still possible, the real challenge was to fabricate such a truss which could span not just 50 meters but cantilever 50meters as it had to be launched as well in position. This truss also had to carry 800 Tonnes of bridge girder on it.
Well, never say no to a client! We agreed and designed a truss system which would be launched at 50 meters cantilever and the bridge span cast over it. The approaches had to be done for 100 meters as the balanced cantilever portion too had to executed with rammed earth to satisfactory Procter density followed by rubble soling and PCC. On PCC actual rails were laid like train track on which the trolly would run carrying the truss. The only point of extreme concern was that the point where the truss would start to cantilever at front trolly the reaction load into the ground would be very high roughly around 90 Tonnes and could lead to settlement at travel locations and lower the truss while erection. That would be a disaster. Hence a proper slope was provided to the rail track and entire track line was tested with settlements.
The entire cantilever was launched successfully and it took only 14 odd minutes to travel the whole 50 meters. The entire launching was recorded and posted here.