Delhi-Gurgaon Expressway is a 28 km (17 mi) long access-controlled toll expressway connecting New Delhi, the national capital of India, and Gurgaon, an important satellite city of Haryana. The expressway is a part of the Golden Quadrilateral project, which itself is a part of the National Highway Development Project (NHDP) and emphasizes improving road connectivity between four metropolitan cities of India, namely Delhi, Mumbai, Chennai and Kolkata by developing 4–6 lane highways between them. The much-delayed ₹10 billion (US$156.8 million), 27.7 km (17.2 mi) expressway was thrown open on January 23, 2008. It has helped reduce the travel time of hundreds of thousands of commuters and international air passengers. Vehicle users have to pay a toll for using the expressway, which is collected at three points, near the Indira Gandhi International Airport, the Delhi-Gurgaon Border and the 42nd Milestone.