In one of our Bridge sites located in Nandurbar district, the bridge piers were reasonably high as the road level of the bridge had to be above backwaters of Narmada dam. This bridge was almost in no man’s land as there was no power not even workers were available. it is tribal area bordering Maharashtra, Gujrat and Madhya Pradesh. Constructing the piers with slip form was the only option as the pier height was nearly 35 meters in the river. Bringing in an external core agency would have meant bringing reliance on technical expertise and dependence on high level of technology which may not have been suitable at this location.
So the desire was to design a hybrid system reducing the dependence on technology and making the system local so that unskilled workers could also manage the system. A hybrid system was devised with standard formwork of the pier but with steel frame and timber face. This formwork would travel vertically on a system designed to carry vertical slide of the form with the help of a central puling high diameter screw jack which can be mounted on the platform where workers could stand and operate.
A system was thus designed and fabricated along with the screw in workshop and erected at site. This screw jack could pull around 65 tonnes as single unit.
All the workers had to do was to rotate the screw sitting on top manually and the entire system would lift. With concrete possible every day. The piers could be done in a cycle of 2 days completing each pier in a month’s time of 35 meters in a difficult terrain.