CANACONA/PANAJI: Heavy rainfall and faulty construction may have led to the significant crack that opened up on the concrete retaining wall of the newly-built vehicular overbridge on Friday at Canacona. PWDofficials said that part of the retaining wall collapsed, prompting authorities to close down the stretch for motorists and bring in emergency services and heavy machinery to clear the debris and cordon off the area.
As heavy rains lashed Canacona on Thursday night, water began to accumulate and finally gushed down, dislodging soil and creating a fissure between the bridge and the 12mt long retaining wall.
“The excess earth, which is part of the concrete return wall, shifted, probably because of the water gushing,” said PWD superintending engineer Vijaykumar Verenkar. “Whatever part has collapsed will be repaired by the contractor.”
While constructing vehicular overbridges, the approach roads and the structure built to support the span are protected by concrete retaining walls to prevent the soil from being washed away or collapsing.
‘Lack of proper water flow’
When these retaining walls are placed parallel to the embankment, they are known as return walls.
PWD assistant engineer Laxmikant Naik said there is a five-year maintenance clause that makes the contractor responsibile for repairing the road in case of defects and damage.
Canacona police inspector Rajendra Prabhu Dessai, deputy collector Raju Dessai and Canacona fire brigade officer Ravi Pednekar rushed to the spot after being alerted.
Officials said that the development of the crack will delay the completion of the entire project to March 2019. As per PWD engineers, the overhead bridge is part of the new alignment of the national highway, and is being built by M Venkatrao Infra Projects Private Ltd. Naik said that the upper portion of the wall has been demolished to prevent the embankment from sliding further. However, Naik mentioned that the bridge is stable with no damage. PWD officials suggested that the fissure between the retaining wall and the bridge span could have occurred because a proper channel was not created for water to flow down.
Since the portion of the road was considered to be unsafe for regular traffic to flow under the overhead bridge, traffic was diverted via Bhagatwada to avoid any danger from 9am till 1pm on Friday.Naik further said that the pitching work for the bridge was not undertaken properly, and thus the retaining wing wall may have tilted, and hence the crack developed.
Stone pitching is the conventional erosion control technique for bridge embankments and approach roads.