Brace for snarls, massive repairwork planned for Vidyasagar Setu

KOLKATA: Twenty two years after it was commissioned, the most vital organ of the Vidyasagar Setu will be removed and a fresh one implanted. The operation will take at least 9 months to be completed and the best Swiss experts are being brought in for the job. The guardian of the bridge, the Hooghly River Bridge Commissioners, is in a tizzy over the pre-operation arrangements, since portions of the bridge will be blocked off to traffic movement while the repair work is on.
The expansion joint of the bridge, which is considered to be its most integral part, has become so weak that it needs immediate replacement, felt experts of the Indian Institute of Engineering, Science and Technology, Shibpur (IIEST, formerly Besu), that studied the health of the bridge and submitted a report to HRBC, a year ago. Serious questions were raised about maintenance and why no thorough repair work was not taken up over the past 22 years.
The bridge has two expansion joints on its two flanks “ one on the Howrah side (manned by the Howrah Police) and the other on Kolkata side (manned by Hastings police). These joints allow the bridge to expand during summer. Of the two expansion joints, the one on the Howrah end is far bigger and allows the bridge to expand up to 440 millimetres. The smaller one on the Kolkata side allows an expansion on 150 mm. Years of wear and tear have caused corrosion and cracks to appear on the expansion joints and they were showing serious signs of decay.
We had to replace the joints but we were in a fix because the big one is yet not manufactured in India. The old one was of German make but technology has advanced now and we had to import one on which the impact of friction and vibration would have a lesser impact; one that would have a life of at least 30 years, explained Sadhan Banerjee, vice chairman of HRBC. Finally Mageba, a Swiss company was chosen for the job. A total of Rs 2.5 crores will be spent on the expansion joints.
The expansion joint runs through the width of the flank and is 25 metres in length. It's quite a complicated and time consuming job. Each flank of the bridge has three lanes and at a time we will block about five to six metres on one lane, open up the joint completely and replace it,†Banerjee explained adding that at least 70,000 vehicles move on the bridge daily.
Though only one lane will be blocked off to moving traffic, on a high speed corridor like the Vidyasagar Setu, these have chances of causing serious traffic snarls and hence a large number of cops from both Howrah and Kolkata police, along with traffic marshals will be deployed to divert traffic and keep it moving smoothly. Warning signals will be laid throughout to attract drivers attention. The repairwork of the bridge will not end with the expansion joints. Once these are done we will focus on the 152 cables and 80 bearings that hold this longest cable stayed bridge of the country, Banerjee said.
Vidyasagar Setu has 152 cables in a fan arrangement, built using steel pylons 127.62 metres (418.7 ft) high. With a total length of 823 metres (2,700 ft), Vidyasagar Setu is the longest cable–stayed bridge in India and one of the longest in Asia. The deck is made of composite steel-reinforced concrete with two carriageways. The total width of the bridge is 35 metres (115 ft), with 3 lanes in each direction and a 1.2 metres (3 ft 11 in)-wide footpath on each side. The deck over the main span is 457.20 metres (1,500.0 ft) long. The two side spans are supported by parallel wire cables and are 182.88 metres (600.0 ft) long. Vidyasagar Setu is a toll bridge with free bicycle lanes. It has capacity to handle more than 85,000 vehicles in a day.