Milestone early morning launch of bowstring arch bridge for coastal road

The BMC on early Friday morning achieved a significant milestone by connecting the Coastal Road to BandraWorli Sea Link (BWSL). Wary of tidal conditions, a team of engineers installed the giant 2,000 tonne ’bowstring arch’ bridge, which was brought to the Worli site at 2am in a barge.

Despite challenges, the engineers stabilised the 25,000metric-tonne barge amid anticipated sea waves and wind speeds, and successfully set up the arch within 85 minutes.

The mission of launching India’s largest 136mt bowstring arch girder started last

October, with the required parts manufactured in Ambala, Haryana. The pre-fabricated parts were transported to Mazgaon Dock and assembled at Nhava Port in Navi Mumbai. Finally, the girder was transported to Worli on April 25 at 4am. A team of 70 engineers and employees of Hindustan Construction Company (HCC), Hyundai Development Corporation (HDC), and Freight Wings Pvt Ltd were involved with the project for months, a civic official said.

The project team included deputy municipal commissioner (special engineering) Chakradhar Kandalkar, chief engineer (Coastal Road)

Girish Nikam, vice-president of HCC Arjun Dhawan, head of the task Santosh Rai, along with engineers, officials, other employees and labourers. The work kicked off in the early hours of Friday, when the land and seawater maintained near equal temperature. This resulted in stable winds and better conducive conditions for marine work, a senior civic official said. The girder was then brought to the midpoint between the Coastal Road and the BWSL using a barge.

A senior civic official said that the erection time needed is two hours, considering it needed aligning the barge precariously between the piers of the span, which is marked the longest activity. Thereafter, engineers waited for a good wave, swell and wind window, where in 40 seconds the span was lowered to a precise location. These girders, coated with anti-rust paint to protect them from saline water and humidity, are being installed to ensure fishing boats off the Worli coast do not face hassles, he said.

The remaining work includes cement concretisation and waterproofing, and is expected to take another month. The second girder will be brought to the site as planned in May-end. That girder is 143mt long and weighs 2,400 metric tonne.