NHAI flags improper crash barriers, tightens safety standards on highways

The National Highways Authority of India (NHAI) has flagged the installation of improper metal beam crash barriers on some of its highway projects and tightened compliance requirements, making prescribed safety specifications mandatory for future projects and stretches where barriers are yet to be installed.

The highway authority issued a policy circular after finding that crash barriers installed at some locations did not conform to prescribed specifications, including requirements relating to the thickness of metal beams, posts, spacers and channel sections. The latest directions amend NHAI’s December 17, 2024 policy governing the approval and installation of metal beam crash barriers.

Standards made mandatory

Under the revised directions, provisions contained in the relevant Manual of Specifications and Standards and IRC:119-2015 will have to be followed for all future highway projects as well as ongoing projects where metal beam crash barriers have not yet been installed.

Crash barriers are a critical road-safety feature designed to contain and redirect vehicles that leave the carriageway, reducing the risk of vehicles entering opposing traffic lanes, striking roadside hazards or leaving elevated stretches.

NHAI’s intervention assumes significance because deviations in the thickness, strength, dimensions or placement of barrier components can affect their performance during a collision.

Specifications laid down

For three-beam crash barriers, NHAI has prescribed rails with a thickness of 3mm along with 3mm-thick steel posts. The posts and blocking-out spacers will have to be made from a 75mm by 150mm channel section with a thickness of 5mm.

The posts are required to be installed at intervals of two metres and have an overall length of 2,100mm. For W-beam barriers, the rail and steel posts will similarly have to be 3mm thick, while posts and blocking-out spacers must use a 75mm by 150mm channel section with a thickness of 5mm.

W-beam posts will also have to be installed at two-metre intervals, with an overall length of 1,800mm.

Steel quality specified

The highway authority has also laid down requirements governing the quality of steel used in the barriers. E350-grade steel conforming to IS 2062 (Part 1):2025 has been specified for the structures.

Posts, spacers and fasteners must be hot-dip galvanised to protect them against corrosion. NHAI has prescribed a minimum zinc coating of 0.55 kg per square metre for these components.

The specifications are intended to ensure consistency in the strength and durability of barriers installed across national highway projects. Contractors and project authorities will consequently have to ensure that the material as well as dimensions of the safety systems conform to the prescribed standards.

Focus on highway safety

The latest circular comes amid NHAI’s broader push to improve safety and maintenance across the national highway network. Crash barriers form an important part of the “forgiving road” approach, under which road infrastructure is designed to limit the consequences when motorists lose control or make errors.

NHAI has also been strengthening monitoring of highway infrastructure, including through road safety audits and technology-based inspection systems. Earlier this year, the authority announced plans to use artificial intelligence-powered dashcams on route patrol vehicles to detect more than 30 types of defects and anomalies, including damaged crash barriers, pavement problems, faded markings and non-functional streetlights.

The latest directions place greater emphasis on ensuring that barriers are built to prescribed specifications in the first place, rather than relying solely on inspections after installation.

Compliance under scrutiny

The acknowledgement that improper barriers had been used on some NHAI projects has brought the quality of roadside safety infrastructure into sharper focus. The revised policy seeks to remove ambiguity over technical specifications by explicitly requiring compliance with existing manuals and Indian Roads Congress standards.

For highway users, the effectiveness of a crash barrier can become critical when a vehicle leaves its normal path, particularly on high-speed corridors, curves, bridges and elevated sections. Correct installation, therefore, involves not only placing a barrier along the road but ensuring its materials, dimensions and supporting components are capable of performing as designed during an impact.

With the revised specifications now mandatory for upcoming installations, responsibility will rest with highway developers, contractors and supervising authorities to ensure that metal beam crash barriers meet the stipulated standards before they are put into service.