The first phase of a new rapid-transit rail system has opened in the Indian capital, raising hopes of easing the city's chronic traffic snarls, and cutting pollution.

Prime minister Atal Behari Vajpayee waved a green flag to launch Delhi's subway service, then bought a ticket for a ride on the metro's inaugural journey.

Mr. Vajpayee said a dream is being fulfilled for the citizens of Delhi.

The prime minister was echoing a popular feeling in the Indian capital, a sprawling city of 14 million people with no reliable public transport system. Delhi's fleet of buses is woefully inadequate. Rickety, three-wheeler motorized rickshaws and expensive taxis are the only option.

As a result, harassed commuters have begun relying more on personal cars and scooters. The city now has four million vehicles. But they not only clog the streets, they also produce enough pollutants to block out the sky on a cold winter day.

The first stretch of the metro is only a small beginning toward easing these problems. It runs over eight kilometers, connecting an eastern suburb with the inter-state bus terminal in North Delhi. The metro will be expanded over the next four years to run over 60 kilometers of underground and elevated tracks through some of city's most crowded areas. Up to two million commuters are expected to use it daily by then. The project's cost is estimated at $2 billion.

Delhi's metro has been billed as a world class system, completely computerized, with modern train cars, a state-of-the art transport network that is in stark contrast to anything the city has ever known. And many excited citizens want to have a look even if it will not ease their travel burden for the time being.

"I've only seen the subway in movies, and am really waiting to experience it," said Purnima Mehta, who works in an office in South Delhi. "I don't live near the area where it plies, but I am planning to go for a ride."

New Delhi residents are not the only ones to welcome the Metro. Environmental activists in the city have been waging a long battle for a more efficient public transport system to help reduce pollution levels. Among them is Anumita Roy Chowdhury at the non-governmental Center for Science and Environment. She says steps must be taken to reduce the use of private vehicles.

"We know from experience it is very important for us to have a mass rapid transport system in the city, becaue if we don't, then we are going to rely more and more on private vehicles, that means more in number, and that is going to complicate matters," Ms. Chowdhury said.

Delhi is the second city in India to have a metro after Calcutta.

Stations carry detailed instructions on how to use the system. For days, radio announcements have also been warning people against littering the subway, spitting or scribbling on the walls.