Rain pain on TenderSure roads

Rain pain on TenderSure roads

Scenes like this are common on Cunningham Road, one of the city’s first roads to get a TenderSure makeover.

TenderSure roads cost much more than regular roads: the justification was that they ensure smooth traffic and prevent flooding. But when it starts raining, it only takes a couple of minutes for the roads to fill up with water.

Vehicles splash through the roads, making life especially difficult for those on two-wheelers. Bruhat Bengaluru Mahanagara Palike and Bangalore Water Supply and Sewerage Board blame the design. K T Nagaraj, chief of road projects, BBMP, says water gratings are fitted every three metres on TenderSure roads, and that’s not good enough. “The design does not permit more gratings. That’s why water accumulated on the surface of the road takes time to drain out,” says Nagaraj.

He also blames the geometry or gradient. “When it’s windy, dust, leaves and other waste on the roads get stuck between the cobblestones and the gratings. This prevents water from flowing into the drain,” he says. He claims the BBMP cleans the surfaces regularly, and lack of maintenance is not the reason for clogged drains and flooded roads. “We are contemplating a separate sweeping contract exclusively for TenderSure roads,” he said. The main benefit of TenderSure roads is that the utilities are all placed on one side and they don’t have to be dug up at frequent intervals, he says.

BWSSB Chairman Tushar Girinath agrees. He says the number and size of water gratings are inadequate to accommodate the volume of water. “The current problem is high intensity of rain in a short span. The water gratings are unable to handle the increased volume,” he says. He suggests wider pipes under the footpath to accommodate the water.

Review design, says IISc prof

- The capacity required for the stormwater drain has been underestimated, which means groundwater run-off from the road is much higher, and it is not able to cope with the water, says Ashish Verma, associate professor of transportation, systems and engineering, IISc.

His suggestions

- Take a relook at the design of other TenderSure roads. Estimate the surface run-off and see whether they have provided adequate capacity for stormwater drains.

- Cross slope on the road is important. This helps rainwater flow as quickly as possible. The run-off is slow if this is not done properly.

Cost of TenderSure

- 1 km stretch costs between Rs 10 crore and Rs 11 crore.

Prone to flooding

- Cunningham Road, St Mark’s Road, Hayes Road–Residency Road junction.

Why it gets bad

- Ashwin Mahesh, urban planner, cites two major reasons for flooding.

- Road infrastructure has to be thought of as a network. The laying of a road must be done simultaneously with laying the pipes. The connecting infrastructure from the side roads must align with TenderSure roads. That has not been done.

- Fork pits must be built inside the drains, so the water flows into the drain and only excess water flows elsewhere. The gravity flow only makes sense when the eventual destination is well-connected, which is not the case here.

No flooding, says design expert

- Swathi Ramanathan, design consultant who helped create the specifications for TenderSure roads, says she sees “no flooding.” She told Metrolife to direct questions about TenderSure to the BBMP.