KOCHI: As Kochi registers a growing number of vehicles crowding its roads, the city’s infrastructure seems to be creaking under their weight. At least two major flyovers within city limits have developed wide gaps in between girders, severely hampering traffic flow and causing vehicular congestion. The North overbridge close to the Ernakulam Town railway station has three-four inch gaps between expansion joints at multiple points.
“I regularly pass through the North overbridge and the issue has come to my notice. Even though a small gap is necessary, the current situation is causing discomfort to drivers. However, the bridge, along with other flyovers on main roads in the city are under the purview of the Public Works Department (PWD). The corporation has no jurisdiction,” said P M Harris, chairman, standing committee for works, Kochi Corporation.
While small gaps known as expansion joints are incorporated between each girders to accommodate for enlargement and contraction of the bridge owing to changes in temperature, a widening in the joint can lead to a safety hazard for the motorists. “A number of factors can cause the widening of the expansion joint. Heavy vehicular movement, climatic effect or inferior quality of materials in some cases can result in the erosion at the edges of girders. Such issues can be rectified by filling the gap with either bituminous substances or reinforced steel joints,” said Sanjay Kumar V S, senior scientist, National Transportation Planning and Research Centre (NATPAC).
With work on the overlay of the North overbridge on the cards, the widening joints are expected to be filled. “The bridge was constructed by the Kochi Metro Rail Ltd and it was handed over to the PWD after completion for the upkeep. Laying a new coat of bituminous binder has been proposed, the project has been tendered and the formalities will soon be completed. The work is expected to begin very soon,” said a PWD official. The bituminous layer on the Goshree bridge which connects the mainland with Bolgatty, Vallarpadam and Vypeen islands is also chipping away at the joints. With more than 10,000 vehicles passing through the stretch everyday, many being trucks carrying heavy loads, making way to the adjoining International Container Terminal, the bridge has seen significant wear and tear.
“The bridge comprises a rubber joint between two girders. The tarring covering the joint may have chipped away due to expansion and contraction. It is not a matter of serious concern,” said a former top official associated with the Goshree bridge project. “Different strategies and designs are employed while constructing bridges based on the climatic conditions of the place and anticipated load-bearing requirements. The standard expansion gap given is between 25mm to 50mm (0.98 to 1.96 inches), with 50mm being the maximum range.
Kerala does not record extremely adverse temperature fluctuations, hence flyovers can be designed without the need for expansion joints as well. For example, The Salim Rajan Road overbridge in Kadavanthra was built with long steel ‘U’ girders which are affixed without a joint,” says Reji Zachariah, president, Association of Structural and Geotechnical Consulting Engineers (ASGCE).