NHAI Orders Testing of Materials Used in Mumbai Expressway After Damage and Rutting Issues
The National Highways Authority of India (NHAI) is taking swift action following reports of rutting—permanent depressions in the road surface—on the Sohna-Dausa section of the Mumbai Expressway. This issue, which surfaced less than two years after the expressway’s inauguration, has raised concerns about the quality of materials used in its construction. The NHAI has since ordered a detailed investigation into the Stone Mastic Asphalt (SMA) material used in this and other highway projects to prevent further incidents.
The rutting damage on the Sohna-Dausa section, which became a major issue last year, has prompted the NHAI to review the materials used in the construction of several stretches of highway. A thorough investigation has identified several factors contributing to the premature damage of the expressway. Poor quality SMA, inappropriate aggregate size, and the use of incorrect bitumen grades were all pinpointed as the key causes of the damage. SMA, a high-quality material commonly used in road projects for its strength, durability, and resistance to deformation, had been used in the construction of the expressway. However, the investigation revealed that the aggregate size used in the SMA was only 13 mm, while the recommended size for the project was 19 mm. This difference in aggregate size was found to be one of the primary reasons behind the rutting problem. The investigation also discovered that the bitumen grade used could not withstand the high temperatures the highway experienced during the summer, exacerbating the problem.
Experts from IIT-Kharagpur, who conducted the investigation, found that rutting predominantly occurred during the summer months when the temperature of the upper asphalt layers exceeded 70 degrees Celsius. Under these extreme conditions, the bitumen used in the construction was unable to perform as expected. The engineers recommended using a higher grade of bitumen and replacing the faulty SMA layers in sections where the rut depth was more than 10 mm. The solution proposed involves re-laying sections with 50 mm SMA, using the appropriate 19 mm aggregate and superior bitumen to ensure the longevity of the road surface. In response to the findings, Nitin Gadkari, the highway minister, stated that show-cause notices have been issued to several contractors involved in the project, including APCO, CDS Infra, HG Infra Engineering, KCC Buildcon, and Gawar Construction. The minister assured that strict action would be taken against the contractors and consultants based on the final investigation report, as per the provisions of the contract.
Additionally, show-cause notices have also been issued to NHAI officials who were involved in the supervision of the project. This indicates the seriousness with which the issue is being handled, with accountability being taken at multiple levels. As part of a broader initiative to ensure that such issues do not recur, the NHAI has mandated the testing of SMA materials across all other highway projects where this material has been used. This will help determine if similar quality deficiencies exist elsewhere, potentially preventing further damage to other stretches of road. A circular issued by the NHAI also highlighted concerns regarding the quality of SMA on completed projects, instructing agencies to implement the technology correctly to avoid premature distress or rutting. If any issues are detected in the SMA or Dense Bitumen Macadam (DBM) used as base material, more samples will be sent for testing. Rectifications will then be carried out in consultation with domain experts.
For Mumbai commuters, the rutting issues on the expressway are more than just an engineering flaw—they represent a significant inconvenience. Rajesh Kumar, a daily commuter from Thane, shared his frustration, saying, “I have been driving on this expressway for almost a year, and the uneven surface has caused multiple discomforts, including a few near-miss accidents. It’s concerning that such a vital project is facing issues so soon after its completion.” Others, like Neha Sharma, a resident of Sohna, believe that addressing these issues swiftly will improve the overall safety and durability of the expressway. “It’s good that the authorities are taking this seriously. The expressway is a crucial part of our daily commute, and it’s essential that it’s built to last,” she said. The NHAI’s proactive steps to address the damage to the Mumbai Expressway highlight the importance of quality control and material testing in infrastructure projects. With ongoing investigations and remedial measures being implemented, authorities hope to ensure that the expressway, along with other highway projects, is built to withstand the challenges posed by weather conditions and heavy traffic. This incident serves as a valuable lesson in ensuring road durability and accountability in public infrastructure projects.
