Metro-II: to get it right,a grid map

Reliance Infrastructure Ltd teamed up with Canada-based SNC Lavlin to bag the Rs 8,250-crore contract. According to RInfra,Fugro,a Netherlands-based agency,has been roped in to carry out the topography survey for the Charkop-Bandra-Mankhurd corridor. “With the DGPS,the probability of the error is minimal. It has phenomenal accuracy and will have significant improvement,” said K P Maheshwari,Senior Vice President,RInfra.

He added,“Three teams are working on the survey. In this technology,devices called control pillars have been placed at an interval of 50 metres throughout the 32 km stretch either on the curb or pavement available. Values (coordinates both vertical and horizontal) are collected from nine satellites rented by the agency.” Fifty per cent of the survey is completed while the rest is expected to complete by November-end.

RInfra which is also constructing the first metro from Versova to Ghatkopar via Andheri did not use the DGPS technology for topography survey and mapping alignment there. “We’ve learnt lessons from the construction of the first corridor and have worked on it. In first corridor Triangulation Method was used. Through the sophisticated DGPS technology the time for the survey has reduced five times,” Maheshwari added. According to him,even if the control pillars get damaged on the road it is easier to continue the mapping as next control pillar is just 100 metres away.

Meanwhile,the agency has begun facing hiccups in the survey especially at a stretch in Kurla—over 1 km—which is heavily encroached upon. “We’re facing problem in Kurla. Our surveyors are not being allowed to enter the area by the slum dwellers to carry out the work. We will need MMRDA to tackle the issue,” Maheshwari said. Apart from this they also need permissions from Railway authorities for allowing survey at Bandra,Kurla and Mankhurd.