Explained: Why BMC has been forced to re-audit bridges across Mumbai

The BMC audit suggested immediate demolition and reconstruction of 29 bridges since they were declared 'extremely dilapidated'. The civic body has either closed bridges to traffic or demolished more than 20 bridges out of these dilapidated structures.

The audit started in 2016 and ended in 2018. But after another bridge collapsed outside the CSMT in March, the civic body re-audited 304 bridges across Mumbai. (Express photo by Dilip Kagada/File)

Why has the Brihanmumbai Municipal Corporation (BMC) started a structural audit of bridges in Mumbai?

In last three years, two incidents of bridge collapse — one at Savitri River in Mahad that killed 41 in 2017 and other at Gokhale Bridge in Andheri that killed two in 2018 — have forced the corporation to carry out a structural audit of bridges in Mumbai since most of them are old and lack regular maintenance.

The audit started in 2016 and ended in 2018. But after another bridge collapsed outside the CSMT in March, the civic body re-audited 304 bridges across Mumbai. The audit suggested immediate demolition and reconstruction of 29 bridges since they were declared ‘extremely dilapidated’. The BMC has either closed bridges to traffic or demolished more than 20 bridges out of these dilapidated structures.

How does the BMC carry out structural audits of bridges?

The BMC appoints contractors that are specialised in carrying out the structural audit of bridges. The firm is finalised first to do a visual inspection of the structure and in case they find any corrosion or fault, it further takes up the audit of the bridges with the help of machines. There are few specialised techniques like Non-Destructive Test, Pulse Velocity and others through which structural stability of the bridge can be ascertained.

Following the finding of the audit, the firm submits a report before BMC suggesting action depending upon whether it is fit or if it needs minor repair, major repairs, demolition and reconstruction. If the bridge’s structural stability is very weak then it requires immediate demolition.

What is the procedure of the maintenance of bridges? Who is responsible to check the structures?

As per the manual of maintenance of Bridges department, Sub-Engineer and Assistant Engineer of the respective ward (there are 24 administrative awards) are directly responsible for the repair and maintenance of the bridges that fall in their jurisdiction. According to the officials, painting of bridges should be carried out every three years along with regular inspections depending upon the age of the bridge. There are 314 bridges (Road over the bridge, flyover, skywalks, Foot over Bridge, Bridge over nullah, subways) across the city.