Mumbai’s pothole problem is often described as a failure of road construction. The evidence in a recent report, however, points to a more complicated chain of causes: pavement design, material quality, compaction, drainage, traffic loads, maintenance and repeated utility trenching. The contrast between the largely pothole-free Bandra-Worli Sea Link and damaged stretches of ordinary city roads makes the distinction visible.
The 17-year-old Sea Link and newer stretches of the Coastal Road have generally held up better than several municipal roads, even though both use bitumen or asphalt in parts of their pavement systems. That does not mean major projects are immune from wear. An MSRDC engineer cited in the report said minor defects are addressed through routine maintenance and patchwork, while complete surface renewal is usually carried out at intervals of around five years, depending on the condition of the road.
The key difference is not simply that one road is new and another is old. It is also how the pavement is designed, what lies beneath it and whether its structural layers remain intact after construction. On the Sea Link, resurfacing must account for the bridge’s structural limits. A new layer cannot simply be placed over the existing surface because that would increase the load and alter the road level. During complete renewal, the existing surface is removed to a depth of 25 millimetres and replaced with a new layer of the same thickness.
That method maintains the original road level while avoiding unnecessary additional load on the bridge. The engineering problem is therefore not limited to putting down a fresh surface. It involves maintaining the relationship between the wearing course, the bridge deck and the structure below it. The report identifies the Sea Link’s original wearing course as 65 millimetres, comprising a 40-millimetre bituminous carpet and 25 millimetres of mastic asphalt.
Ordinary municipal roads operate under a different set of pressures. Girish Jaysing Arekar, a council member of the Indian Road Congress, said a road built according to IRC norms and properly maintained should not develop potholes within a few months. On high-traffic roads, gradual wear is expected, but early potholes indicate that one or more parts of the pavement system may not be performing as intended.
Arekar identified several possible causes: poor-quality bitumen or aggregates, incorrect laying and rolling, inadequate compaction, weak drainage, an incorrect camber and heavy traffic. These factors can interact. A road with weak compaction may be more vulnerable to water penetration. A road with poor drainage may allow water to remain on or beneath the surface. Repeated heavy loads can then accelerate the damage.
The role of water is particularly important. Bitumen and water do not work well together, Arekar said, and even a well-built road can develop potholes if water remains on or below the surface. Mumbai’s monsoon makes drainage and pavement protection central to road performance. The relevant question is not only whether a road was built to a specified standard, but also whether rainwater is quickly removed from the pavement and its underlying layers.
Traffic adds another stress. Trucks, trailers and other heavily loaded vehicles can produce repeated strains, leading to cracks and other weaknesses in the pavement. Once water enters those cracks, deterioration can accelerate. This does not establish that heavy traffic alone causes Mumbai’s potholes. Rather, it shows how traffic can amplify weaknesses created by materials, workmanship or drainage.
The most consequential distinction identified by the BMC concerns what happens after a road is built. Abhijit Bangar, the municipal corporation’s additional commissioner for projects, said BMC road tenders include mandatory technical requirements based on IRC guidelines. These include specifications for layer depths, materials, thicknesses, compaction, testing, concrete mix design, aggregates and water-cement ratios.
According to Bangar, the broad quality standards in contracts for major projects and conventional municipal roads are not fundamentally different. Design and drainage requirements vary according to the structure: a bridge requires a different approach from a flat road, while flexible asphalt pavement and rigid concrete pavement have their own standards. Contractors are expected to follow the applicable requirements in each case.
This is where the distinction between formal standards and actual road performance becomes important. A tender may specify the required materials, layer thicknesses and testing procedures, but a finished road can still fail if the work is poorly executed or if its integrity is later disrupted. Bangar acknowledged that poor contractor workmanship remains a factor and said harsher penalties and other systematic changes are required.
Utility trenching is the clearest example of post-construction damage. Most regular Mumbai roads contain electricity lines and other utilities beneath them. Authorised and unauthorised digging can cut through the pavement and disturb its layers. Even when a trench is repaired, the restored section may not perform like an undisturbed road unless excavation, backfilling, compaction and resurfacing are carried out to the required standard.
By contrast, the pavement on the Sea Link and Coastal Road has largely remained intact because its structural integrity has not been repeatedly interrupted by utility work, Bangar said. This does not make these projects inherently immune to potholes. It means that one major source of vulnerability present on many ordinary roads is absent or significantly reduced.
The comparison also explains why the use of asphalt alone cannot account for the difference. Roads with similar surface materials can perform differently depending on their foundation, drainage, traffic load, maintenance regime and exposure to excavation. The issue is therefore less about choosing one universal material and more about preserving the complete pavement system over time.
The BMC’s preference for cement-concrete roads in some circumstances is connected to this maintenance challenge. Bangar said trenching on concrete roads is more precise and does not cause the same degree of wider damage associated with flexible asphalt roads. Concrete roads are also more durable, although the source material does not establish that they are suitable for every Mumbai street or that they eliminate all maintenance problems.
This points to a wider governance problem. Road quality is shaped by several agencies and stages: design, tendering, construction, inspection, utility coordination, excavation approvals, reinstatement and post-monsoon maintenance. A weakness at any one stage can reduce the life of the road. Responsibility for the visible pothole may therefore lie far from the moment when the pavement first became vulnerable.
The available evidence does not establish how many Mumbai roads fail because of poor materials, defective construction, inadequate drainage, heavy traffic or utility cuts. Nor does it provide a citywide comparison of road life, repair costs or contractor performance. Those gaps matter because the public experience of potholes is widespread, while the causes are likely to differ from one road to another.
What the evidence does establish is that Mumbai’s road problem cannot be reduced to a single explanation. The Sea Link’s maintenance regime, controlled resurfacing method and uninterrupted pavement integrity offer one contrast. The BMC’s account of municipal roads shows that formal IRC-based requirements coexist with trenching and acknowledged workmanship concerns. The experience of potholes on roads such as Akurli Road in Kandivli and near Mehboob Studio and Poisar Metro station illustrates the citizen-facing result.
The central urban question is whether Mumbai treats roads as finished projects or as long-term systems requiring coordinated maintenance. Construction standards matter, but so do drainage, utility mapping, excavation controls, reinstatement quality and enforcement during the defect liability period. Until those elements are managed together, a road can comply with specifications at the time of construction and still become vulnerable soon afterwards.
The report confirms that better-performing roads are not explained by one material or one project label. Their performance reflects the interaction of engineering design, construction quality, traffic, water management and the protection of pavement integrity after completion. The developments that warrant monitoring are the BMC’s proposed systematic changes, the enforcement of contractor obligations and whether utility trenching and road reinstatement are managed with the same rigor as initial construction.
