The Bruhat Bengaluru Mahanagara Palike (BBMP) has begun implementing Stone Matrix Asphalt (SMA) resurfacing on major city flyovers in a bid to ensure greater durability and reduce long-term maintenance costs. The move comes as part of the civic body’s broader pre-monsoon infrastructure efforts and reflects a shift away from patchwork methods that often fail within a short span.
Earlier this week, the BBMP completed SMA resurfacing on the Hebbal flyover, and has identified other key structures for similar treatment, including flyovers near Shri Gali Anjaneya Temple, Benniganahalli (Tin Factory), and stretches along the Outer Ring Road.
Why SMA is Gaining Ground?
SMA is a high-performance asphalt mix widely used on national highways and large bridges, known for its stone-on-stone contact structure, higher bitumen content, and cellulose fiber additives. These features enhance load distribution, skid resistance, and resistance to rutting and weather-induced damage—factors critical for city flyovers exposed to heavy axle loads and monsoon impact.
“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. He added that BBMP had used SMA on KG Road, which remained pothole-free for over six years.
Track Record and Experience with SMA
The BBMP has previously implemented SMA technology on Margosa Road, Modi Hospital Road, KR Circle, and the HAL underpass, approximately two to three years ago. These areas have reportedly shown better surface retention compared to traditional bituminous roads.
Nationally, SMA has found favour in major infrastructure projects such as Mumbai’s Trans Harbour Link, India’s longest sea bridge. Despite its higher cost, it is considered a better investment for urban corridors that are difficult to maintain once traffic resumes.
Cost vs. Long-Term Benefits
Although SMA resurfacing involves higher upfront expenditure than conventional bitumen layers, officials argue that it yields significant lifecycle savings by reducing the frequency of patch repairs. “If roads are properly designed and constructed, SMA can last up to 10 years,” said Kishore Kumar M, a pavement design expert. “But it requires specialised equipment, strict quality control, and high-grade materials — something not many contractors can deliver.”
The BBMP is aware of these technical requirements and is now exploring contractor training programs and better quality enforcement to ensure correct execution. Officials also revealed that the civic body intends to closely monitor the performance of the Hebbal stretch before finalizing further contracts.
Towards a More Resilient Road Network
BBMP engineers say that older flyovers in Bengaluru face rapid surface degradation due to factors such as heavy traffic volume, water infiltration, and temperature fluctuations. By adopting SMA, the agency aims to mitigate these issues while enhancing road safety through better surface grip.
In addition to flyovers, BBMP is considering SMA resurfacing for high-density corridors leading to the airport, tech parks, and intermodal junctions, citing the need for long-lasting surfaces on critical routes.
The Hebbal resurfacing is part of a larger initiative that also includes the overhaul of arterial roads and drainage improvements at key junctions. BBMP is attempting to fast-track these works before peak monsoon sets in, hoping to minimize disruptions and emergency repair costs during the rainy season.
Experts and civil engineers have largely welcomed BBMP’s move to adopt SMA, especially given Bengaluru’s high rainfall and intense traffic density. However, they caution that for SMA to be effective, strict supervision, material certification, and continuous, high-temperature laying processes must be adhered to—areas where municipal works often fall short.
