FCC

Greater Chennai Corporation constructs Steel Flyover in T Nagar

2023-07-18

In order to expedite the construction process, the Greater Chennai Corporation is currently erecting a steel flyover in T Nagar on the heavily congested South Usman Road. According to officials, this will be the second fully steel bridge in the state, with the first one located in Marthandam, Kanyakumari district.

S Rajendiran, the chief engineer (general) of the Corporation, explained that the concrete pile and pile cap are situated underground, while the pier, pier cap, and deck girders, made of high tensile steel, are manufactured in Trichy and transported to the site. Placing these components takes only a few hours. On top of the girders, a steel deck sheet is installed, followed by a 20-cm thick concrete slab and a bitumen road.

The flyover spans 1.2 kilometers and connects Anna Salai and T Nagar via CIT Nagar. The project is estimated to cost 13.1 billlion. Once completed, it will be connected to the existing concrete North Usman Road flyover, allowing commuters traveling from Anna Salai to cross Panagal Park in less than five minutes.

The steel flyover stands at a height of 6.5 meters, with underground support reaching approximately 30 meters deep. Rajendiran mentioned that there are exit and entry ramps near Ranganathan Street for vehicles coming from T Nagar and shoppers. Unlike concrete bridges where expansion joints are typically 20 meters apart, in this steel flyover they are spaced 75 meters apart, resulting in smoother rides for vehicles. The two-lane flyover will consist of 53 steel piers and three 8.5-meter-wide girders.

A professor of structural engineering from IIT-M, who is collaborating with the Greater Chennai Corporation on the project, highlighted the use of high-quality steel for the bridge, which is expected to have a lifespan of around 50 years. The decision to use steel was made to minimise construction time, given the congested nature of the T Nagar area. Barricading all the spots for an extended period would not be feasible.

Rajendiran mentioned that static and dynamic testing was conducted, including static load and moving load tests. "We applied a weight that was 2.5 times more than the prescribed amount for additional safety," he added.

G Sameeran, the Deputy Commissioner (Works), stated that the initial deadline for completion was set at 24 months. However, thanks to the implementation of steel structures, the project is expected to be finished in less than 20 months, by late 2024.