NHAI Issues Design Guidelines for High-Speed National Highways
NHAI's new guidelines standardise planning of four- and six-lane access-controlled National Highways, covering boundary walls, interchanges and lane norms.
The National Highways Authority of India has issued fresh guidelines for planning and designing four- and six-lane access-controlled National Highways, a move aimed at standardising how upcoming high-speed corridors are built.
The rules will apply to upcoming greenfield and brownfield projects, though expressways fall outside their scope. Access-controlled highways permit vehicles to enter or exit only at designated points, rather than allowing direct access from adjoining roads or properties.
Until now, there were no separate design standards for such high-speed National Highways, which led to variations in Detailed Project Reports across projects. The new framework sets common technical and safety requirements.
Boundary walls to keep out stray cattle
High-speed corridors will have a one-metre-high boundary wall along their outer edge. The wall is intended to prevent stray cattle from entering the carriageway and to curb encroachments and unauthorised access.
Advance warnings before entry and exit points
Motorists will receive advance warnings ahead of upcoming entry and exit points, giving them more time to prepare before joining or leaving a high-speed corridor. The measure is part of additional safety provisions prescribed for roads carrying high-speed traffic.
Width and lanes linked to traffic volumes
The width and number of lanes will be decided on the basis of a detailed traffic assessment. Corridors expected to handle up to 15,000 vehicles will have four lanes and four-lane structures within a width of 60 metres. For traffic between 15,000 and 25,000 vehicles, the highway will have four lanes and six-lane structures within a width of 70 metres. Highways handling between 25,000 and 40,000 vehicles will have six lanes and six-lane structures, also within a 70-metre width.
Ramp interchanges at major crossings
Ramp-based interchanges will be provided where high-speed highways cross expressways, National Highways, State Highways and important arterial roads carrying substantial traffic. These will offer designated entry and exit points while allowing traffic on the main corridor to keep moving.
Better access to airports, ports and industrial hubs
Roads connecting airports, ports, Multi-Modal Logistics Parks, industrial areas and major tourist destinations will also get ramp-based interchanges, on routes serving destinations that generate substantial traffic.
The guidelines lay down common rules for highway width, number of lanes, entry and exit points, interchanges and access control. They come as the government plans a much larger network of high-speed roads, with a long-term roadmap envisaging around 50,000 km of access-controlled high-speed corridors by 2047.