The National Highways Development Project (NHDP) was a project of four laning of existing national highways and six laning of selected major national highways of India. The project was started in 1998 under the leadership of Prime Minister, Atal Bihari Vajpayee. National Highways account for only about 2% of the total length of roads, but carry about 40% of the total traffic across the length and breadth of the country. This project is managed by the National Highways Authority of India (NHAI) under the Ministry of Road, Transport and Highways. The NHDP represents 49,260 km of roads and highways work and construction in order to boost economic development of the country. The government has planned to end the NHDP program in early 2018 and subsume the ongoing projects under a larger Bharatmala project.

Project Phases

The project is composed of the following phases:

• Phase I: The Golden Quadrilateral (GQ; 5,846 km) connecting the four major cities of Delhi, Mumbai, Chennai and Kolkata. This project, connecting four metro cities, is 5,846 km (3,633 mi). Total cost of the project is Rs.300 billion (US$6.8 billion), funded largely by the government’s special petroleum product tax revenues and government borrowing. In January 2012, India announced the four-lane GQ highway network as complete.^[1][2]
• Phase II: North-South and East-West corridors comprising national highways connecting four extreme points of the country. The North–South and East–West Corridor (NS-EW; 7,142 km) connecting Srinagar in the north to Kanyakumari in the south, including spur from Salem to Kanyakumari (Via Coimbatore and Kochi) and Silchar in the east to Porbandar in the west. Total length of the network is 7,142 km (4,438 mi). As of 31 October 2016, 90.99% of the project had been completed, 5.47% of the project work is under Implementation and 3.52% of the total length is left.^[3][4] It also includes Port connectivity and other projects — 435 km (270 mi). The final completion date to 28 February 2009 at a cost of Rs.350 billion (US$8 billion), with funding similar to Phase I.
• Phase III: The government on 12 April 2007 approved NHDP-III to upgrade 12,109 km (7,524 mi)of national highways on a Build, Operate and Transfer (BOT) basis, which takes into account high-density traffic, connectivity of state capitals via NHDP Phase I and II, and connectivity to centres of economic importance.
• Phase IV: The government on 18 June 2008 approved widening 20,000 km (12,000 mi) of highway that were not part of Phase I, II, or III. Phase IV will convert existing single-lane highways into two lanes with paved shoulders.
• Phase V: As road traffic increases over time, a number of four-lane highways will need to be upgraded/expanded to six lanes. On 5 October 2006 the government approved for upgrade of about 5,000 km (3,100 mi) of four-lane roads.
• Phase VI: The government is working on constructing 1,000 km (620 mi) expressways that would connect major commercial and industrial townships. It has already identified 400 km (250 mi) of Vadodara (earlier Baroda)-Mumbai section that would connect to the existing Vadodara (earlier Baroda)-Ahmedabad section. The World Bank is studying this project. The project will be funded on BOT basis. The 334 km (208 mi) Expressway between Chennai—Bangalore and 277 km (172 mi) Expressway between Kolkata—Dhanbad has been identified and feasibility study and DPR contract has been awarded by NHAI.
• Phase VII: This phase calls for improvements to city road networks by adding ring roads to enable easier connectivity with national highways to important cities. In addition, improvements will be made to stretches of national highways that require additional flyovers and bypasses given population and housing growth along the highways and increasing traffic. The government has planned to invest Rs. 16,680 Cr for this phase. The 19 km (12 mi) long Chennai Port—Maduravoyal Elevated Expressway is being executed under this phase.

Note: 1 crore= 10 million

"Financing of the National Highway Development Programme" (PDF). Archived from the original (PDF) on 28 February 2007.

Status from NHAI website

National Highways Development Project is being implemented in all phases. The present phases are improving more than 49,260 km of arterial routes of NH network to international standards. The project-wise details of NHDP all phases is below as of 18 May 2021:

Subsummation in Bharatmala project

National Highway Development Project will close by first half of 2018, with the launch of Bharatmala project.^[6] 10,000 km of highway construction left under NHDP will be merged with Phase I of the Bharatmala.^[6] Sagarmala and Setu Bharatam are also expected to fill in the void created by closure of NHDP project.^{[citation needed]}