Explained: Why is Mumbai’s GMLR flyover partially shut down?

Traffic on the Ghatkopar Mankhurd Link Road flyover had to be stopped after multiple complaints were received about incidents of motorbikes skidding on the bridge during the rain, raising questions about the quality of construction.

The 2.9-km Ghatkopar Mankhurd Link Road Flyover, which is Mumbai’s costliest flyover so far, had to be partially shut down a month after it was thrown open to the public. Its excessively slippery roads have led to a number of bikes skidding on the surface, which led to one person losing his life this week. A look at why accidents are occurring on the flyover and the steps being taken by the BMC to address the problem.

When was the flyover thrown open for public use?

The Ghatkopar Mankhurd Link Road flyover, constructed by BMC, was thrown open to light vehicles on August 1. Built at a cost of Rs 713 crore, the flyover is crucial for motorists as it reduces the travel time by 25 minutes on congested Ghatkopar-Mankhurd Link Road, especially on Baiganwadi Junction at Shivaji Nagar, by connecting it to the road leading towards Vashi.

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Why has traffic on the flyover been stopped?

The decision was taken after multiple complaints were received about incidents of motorbikes skidding on the bridge during the rain, raising questions about the quality of construction. Several bike-skidding accidents have taken place on the northbound (towards Mankhurd Mandala) side since the flyover was opened. A 34-year-old pillion rider lost his life after the bike he was travelling on slipped on the bridge due to rain on Monday afternoon.

Which stretch has been shut down?

The northbound stretch of the flyover was shut down on Wednesday for repairs and will remain closed for the next four days until Sunday. The southbound stretch will be shut for a few days for repair after work on the northbound stretch is completed.

Why are accidents occurring on the road stretch?

Experts believe the improper use of mastic asphalt has made the roads slippery. Mastic asphalt is an upper surface coating of a mixture of ingredients like bitumen or asphalt, fine aggregate like fine natural sand or soil crushed out of stones and other filler material which is layered on the dense graded aggregate (mixture of asphalt, crushed stones,soil) on the road and it works as waterproofing material for roads and bridges. The composition of this top layering has to be such that it provides enough friction for vehicles to grip the surface. In the present case, the top layer does not provide the necessary friction for vehicles to grip the road leading to their skidding. The problem is further accentuated during rains as the water further reduces friction between the tyres and the road surface.

Retired professor S L Dhingra from IIT and a road expert said: “A few years ago when Eastern Express Highway was built, a similar issue had surfaced and at that time it was revealed that the contractor had not used the proper friction course, which is fine aggregate in the mastic asphalt mixture. A particular process has to be followed to make a proper mastic asphalt in which the fine aggregate, mastic and asphalt/bitumen is mixed in a particular ratio and then it’s heated for a particular time and temperature. On the GMLR, too, similar things must have happened.”

What are the reasons for using mastic asphalt?

Experts and officials claim that the mastic asphalt is waterproof, smooth and the inner layers of the roads are protected because of this, making them less vulnerable to the impact of rains or puddles which cause potholes.

What does the BMC say?

The BMC has started work on the road and is using the milling technique that will decrease the smoothness of the surface and provide better grip for vehicles. BMC officials have, however, said that there is nothing wrong with the construction of the road or the flyover and most of the accidents have occurred due to vehicles over speeding on the flyover.

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