Is white trim the best solution to Bengaluru’s pothole threat?

Photo: Seema Prasad

They are not only a danger to life and physical integrity. Bangalore’s rutted roads also inspire artists and activists to be creative in their ways of protesting the poor condition of the city’s roads.

While the artist Badal Nanjundaswamy Frequently draws inspiration from a well-formed pothole to unleash creativity, activists from the Aam Aadmi party recently organized a Pothole Habba to “celebrate” the potholes of the city.

Bruhat Bengaluru Mahanagara Palike (BBMP), the city’s civic body responsible for ensuring road quality, had, in 2018, drawn up a major road concreting plan to clear out potholes, presumably (and arguably ) forever. Called white screeds, these are rigid pavements made mostly of concrete rather than black coated or asphalt roads known as flexible pavements, made of crushed stone and sand and bonded with bitumen.

“The BBMP completed the 100 km white capping on 150 km of roads in the first two phases of the project,” said Lokesh, chief engineer, BBMP. Government approval is expected to launch Phase 3 which will cover 121.72 km, apparently at an estimated cost from Rs 1183.11 cr.

White trim has its advantages

Some Bengalurians have always viewed with suspicion (in many cases and rightly so) the large infrastructure projects and plans mentioned by the government. The white covering of roads seemed to be another example of a waste of taxpayer money. Research, however, suggests that white-roofed roads have some advantages. On the one hand, they are more robust with little chance of developing cracks or potholes. Thus, these concrete rigid pavements could well be a long-term solution to recurring potholes.

Read more: “Reorganizing the entire road repair system – Why wait for the rains?

However, they are more expensive, almost double the cost of laying asphalt roads. But their durability makes them more profitable. An argument often advanced by the BBMP to justify the white topping.

Along with longer life, the white trim also reduces maintenance requirements. The associated benefits – in terms of both economic and productivity benefits – of better maintained roads must also be considered here.

Another feature of white-roofed roads is their high albedo effect compared to asphalt roads. Albedo is the reflectivity of a surface. A high albedo surface reflects more solar radiation back into the atmosphere, while a low albedo surface absorbs solar radiation. Asphalt roads thus absorb more heat, raising the surface temperature, while white-roofed roads reflect light, making the surface cooler.

A study says reducing absorbed solar energy using reflective coatings is a cost-effective approach to reducing surface temperatures. The study further suggests that the albedo of white-top pavements in cities can mitigate urban heat islands (UHIs), a phenomenon where an urban or metropolitan area becomes warmer than its surrounding areas.

Sree Kumar Kumaraswamy, head of integrated transport at the World Resources Institute, however, believes that white flooring alone cannot bring about changes in UHI. “But it can help cool the surface temperature along with other factors like better tree cover.”

File image of white trim in HRBR layout
File photo of the white trim in the HRBR layout. Credit: Seema Prasad

Roads with a white roof are also preferable for traveling at night, especially in the absence of proper street lighting, as they can reflect light better than a road with a black roof. However, be aware that white-roofed roads also contribute more than the desirable amount of glare during the day, which makes driving stressful. Another study notes that the concrete surfaces Rigid pavements experience various mechanical abrasions such as tire slippage and wheel rolling, which reduces surface friction and makes the road slippery and unsafe to use in wet weather.

Environmental impact of concrete

Studies on the environmental impact of cement suggest that concreting roads and buildings is not an ecological solution to the problems of urban citizenship. The cement industry is one of the most polluting industries in the world. According to the Canadian Cement Association, 730 kg of CO2 is produced per 1,000 kg of Portland cement.

A study the comparison of the environmental impact of asphalt and concrete pavements reveals that the greenhouse gases emitted by asphalt pavements represent only 51.9% of the greenhouse gases emitted by concrete pavements, mainly in due to the chemical processes used in the production of cement.

Can White Trim Solve Bengaluru’s Pothole Mess?

The laying of concrete pavements requires proper road mapping and planning with other civic agencies such as BESCOM, BWSSB, etc. before the roads are laid. You can’t dig it up every time there is other civic work to be done under it, which we see happening frequently in Bangalore.

Read more: Urban Utilities Map Beku: what lies under the roads of Bengaluru

“You need heavy machinery to dig a rigid pavement and it is not profitable to continue digging a concrete road which is already expensive to build,” explains Professor Ashish Verma, head of the sustainable transport laboratory at the IISc.

Sreekumar agrees. “While white covered roads are a solution to bad roads in a city, the problem arises when such projects are not planned side to side. Other services such as sewer lines, manholes, etc. that require frequent maintenance should pass under the sidewalk and not under white-roofed roads. For this, good road mapping and prior coordination with other civic agencies are essential, ”he says.

File image of white trim in HRBR layout
File photo of the white trim in the HRBR layout. Workers were digging under the road to place conduits to connect the drains on either side of the road. Credit: Seema Prasad

And Bengalurians fear this is where the BBMP is floundering. “The white-topped road in front of the Forum Mall has already been dug up,” said S Sreeram, a Koramangala resident, who doesn’t trust the BBMP to do a good job or finish the job on time. “White roofing works on some roads in Koramangala that started before the pandemic are continuing,” Sreeram said. And the long-stalled Ejipura flyover work is one example of why he believes incomplete civic work in the city is a real threat and the white trim is only contributing to chaos.

The news that the BMRCL will open the white-topped section of the Outer Ring Road to erect pillars for the subway corridor only added to skepticism about the BBMP’s white crowning plans.

Ashish thinks that it is not necessary to cover so many roads in the city with white. “It is ridiculous that even asphalt roads in good condition are covered in white,” says Ashish. “If properly laid and maintained, asphalt roads have a lifespan of 5 to 10 years. But we end up laying roads every year because the authorities do not apply the basic civil engineering solutions, forcing the citizens to face terrible roads all year round.

“In the case of asphalt roads, bitumen binds aggregates like metal and sand. When water remains on the bitumen for a long time, a chemical reaction called the stripping effect occurs, with the water stripping the bitumen of its binder quality. And when vehicles run over it frequently, the bitumen gives way and the aggregates fall apart, ”he explains. “The civil engineering solution to this is to not let the water stay on the road, using cross slopes or road cambering and rainwater drains on either side of the road. It is not done diligently ”.

There is no doubt that Bengaluru needs better roads and the white trim has its benefits. But whether the white coating of all of the city’s roads is the most lasting solution to the pothole threat is something that needs to be considered before Phase 3 of the project begins.

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