Key Details
The guidelines establish a common planning and design framework for greenfield and brownfield high-speed national highway projects, addressing variations in the standards previously used to prepare Detailed Project Reports.
Projected Traffic Flow | Highway Configuration | Structure Configuration | Prescribed Width |
|---|---|---|---|
Up to 15,000 vehicles | Four lanes | Four lanes | 60 metres |
15,000–25,000 vehicles | Four lanes | Six lanes | 70 metres |
25,000–40,000 vehicles | Six lanes | Six lanes | 70 metres |
The framework also provides for:
advance notification of entry and exit points for high-speed traffic;
grade-separated interchanges with ramps at crossings with expressways, national highways, state highways and important arterial roads;
interchange connectivity for major destinations such as ports, airports, multimodal logistics parks, industrial areas and tourist centres; and
a one-metre-high boundary wall along the corridor’s outer edge to deter encroachment, unauthorised access and stray cattle.
Uniform Rules Will Apply From the DPR Stage
NHAI’s guidelines cover upcoming four- and six-lane greenfield and brownfield access-controlled national highways. They address the absence of dedicated standards for these corridors, which had resulted in different design assumptions across Detailed Project Reports.
The framework will now guide decisions on lane capacity, structures, corridor width, access points and interchanges before projects are appraised and tendered. It does not approve new corridors or provide construction funding.
Traffic Forecasts Will Shape Present and Future Capacity
Projected traffic will determine the highway configuration. Corridors carrying up to 15,000 vehicles will have four-lane roads and structures, while those in the 15,000–25,000 range will retain four-lane carriageways but use six-lane structures. Corridors projected to carry 25,000–40,000 vehicles will have six-lane roads and structures.
Constructing wider bridges, flyovers and underpasses on selected four-lane corridors can make later expansion less disruptive. It also makes the quality of traffic forecasts critical: underestimation can produce early congestion, while overestimation can increase land and construction costs.
Access Will Be Restricted but Strategically Connected
A one-metre boundary wall, advance exit information and ramp-based interchanges are intended to reduce unauthorised entry and make high-speed movement safer.
Interchanges may connect the corridors with ports, airports, industrial areas, multimodal logistics parks and major tourist destinations. Their placement will need to balance access to economic centres with the uninterrupted movement expected from a high-speed corridor.
The guidelines support the government’s longer-term plan to develop 50,000 km of access-controlled high-speed corridors by 2047. A June 2026 government review reported that 3,644 km of such corridors and expressways were operational.
What Are Greenfield and Brownfield Highways?
Greenfield highways are built on a new alignment, usually across previously undeveloped land. Planners have greater freedom to select the route, control access and design the road for high-speed traffic, although substantial land acquisition may be required.
Brownfield highways upgrade or expand an existing road corridor. They can use established transport routes but must work around settlements, businesses, utilities and existing access points, making widening and full access control more complex.
Policy Relevance
The guidelines move an important set of choices — capacity, land width, future expansion and access locations — into a common national framework. This could reduce inconsistent DPR assumptions and expensive redesign after construction begins.
The harder application will be on brownfield corridors, where complete access control can alter how nearby communities reach homes, farms, businesses and public services. DPR appraisal will therefore need to examine service roads, crossings and local connectivity alongside through-traffic efficiency.
Performance should ultimately be judged through cost changes, traffic flow, unauthorised access and crash outcomes, not simply compliance with the prescribed design at the time of construction.
Relevant Question for Policy Stakeholders: How will NHAI test traffic forecasts and account for local-access needs before fixing corridor width, lane capacity and interchange locations—particularly on brownfield highways where design choices directly affect surrounding communities?
Follow the Full Press Release Here: NHAI Introduces Guidelines for Access-Controlled High-Speed National Highways