BBMP bets big on stone matrix asphalt for flyover repairs

Bengaluru: The Bruhat Bengaluru Mahanagara Palike (BBMP) plans to repair nearly a dozen flyovers across the city using stone matrix asphalt (SMA), a highly durable material increasingly adopted in road construction.

Until now, the civic body mostly relied on micro-surfacing for flyover repairs as a cost-effective option, but it failed to address road undulations and potholes due to its limited thickness.

Earlier this week, the BBMP resurfaced the Hebbal flyover with SMA technology and intends to implement it on flyovers near Shri Gali Anjaneya Temple, Benniganahalli (Tin Factory), Outer Ring Road, and other locations.

"Since the flyovers are generally not dug up by any agencies, we plan to use SMA on key stretches that are not in a good condition. Once resurfaced, the flyovers should last at least five years without major repairs,” said M Lokesh, Chief Engineer, BBMP.

The civic body had previously used SMA on KG Road, which remained pothole-free for over six years, he said.

The technology — a mix of coarse aggregates, binders, and cellulose additives — was also applied on stretches such as Margosa Road, Modi Hospital Road, KR Circle, and the HAL underpass about two to three years ago.

It is mostly adopted on national highways, where road-cutting is uncommon.

Mumbai’s Trans Harbour Link, India’s longest sea bridge, also utilised SMA in its construction.

In Bengaluru, the civic body largely uses bituminous asphalt, which is cheaper, but does not last long due to poor quality checks and supervision. Of late, it has also begun adding concrete layers as a solution to eliminate potholes.

Pavement design expert Kishore Kumar M said that SMA contains more asphalt than traditional hot mix, making it more durable, but also costlier. "If roads are properly designed and constructed, SMA can last up to 10 years,” he said. "But it requires specialised equipment, strict quality control, and high-grade materials — something not many contractors can deliver."