By Matthew Futterman

As the sleek trolley cars of the Hudson-Bergen Light Rail Transit line moved north late last week from Bayonne into Jersey City on a practice run, they passed through a barren stretch strewn with garbage and weeds.

It shouldn't be a wasteland for long.

"That's going to be the new Jersey City Medical Center," said John Johnston, CEO of 21st Century Rail Corp., which built the light rail line, as he pointed to a huge lot near the Jersey Avenue station.

As the trolley glided east toward the office towers near the waterfront, Johnston's tour into the future continued: He pointed to another empty lot near the Marin Boulevard Station -- it will host a retail and residential complex called Liberty Harbor North. Then toward the old Colgate sugar refinery near the Essex Street Station, which is being turned into a condominium complex. On another waterfront lot will rise a 40-story Goldman Sachs tower.

Public officials and developers in the region say none of this promise could have occurred without the light rail line, which on Saturday will begin service from Bayonne to Exchange Place in Jersey City. It is expected to carry 9,200 daily riders initially and as many as 100,000 when it is complete in seven to 10 years.

Conceived in the early 1980s by transportation planners in former Gov. Thomas Kean's administration, the 20.5-mile light rail line will ultimately run from the southern tip of Bayonne to the Vince Lombardi Service Area in Ridgefield. The $2 billion project has already impressed a vast array of supporters who say it will dramatically improve road and rail travel around the region and drive economic development, especially in Hudson County.

While skeptics question whether an urban transit system can catch on in an era when so many people work in the suburbs, and wonder how many commuters will be willing to forgo the convenience of their cars, supporters say the 29 electric trollies eventually will cut highway travel time in half for residents of Morris, Essex, Union, Middlesex and ultimately Bergen counties who commute to work in New York City or the growing corporate developments along the Hudson County waterfront. Beginning next week, commuters will be able to bypass bottlenecks such as the Routes 1&9 and New Jersey Turnpike approaches to the Holland Tunnel by leaving their cars in park-and-ride lots in Bayonne and western Jersey City. They will then be able to pick up the light rail to waterfront offices near Exchange Place or to the PATH and ferries to New York City. Eventually, park-and-ride service will be available as far north as the Vince Lombardi Service Area in Ridgefield.

Allow NJ Transit riders from central and western New Jersey to connect at Hoboken to the entire network of ferries, commuter rail and PATH trains that operate in northern New Jersey.

Reduce air pollution caused by the 66,000 cars that now pass through the Hudson River crossings each morning.

Strengthen the real estate market along the Hudson County waterfront from Jersey City to Weehawken, as well as in depressed areas of Jersey City, North Bergen and Union City.

Transform Bayonne from an economically stagnant, isolated peninsula into a vibrant, growing community.

James Hughes, dean of the Edward J. Bloustein School of Planning and Public Policy at Rutgers University, said the light rail line will dramatically improve life for commuters, make the area a cohesive business community by connecting new businesses in Jersey City with those in Weehawken and Hoboken. The line, he said, will legitimize the Hudson County waterfront as a good place for corporate America to invest.

"If the whole harbor is going to reach its potential, it can't be based on the automobile," Hughes said. "You can't build a 21st century economy on 19th century roads."

No one questions the need for better mass transit in the fastest growing region in the state.

Since the mid-1980s, when New York financial corporations began building back-office space in the abandoned freight yards between Jersey City and Weehawken, Hudson County has added 15,000 homes, 5 million square feet of office space and 30,000 new jobs. Much of that growth occurred because developers believed public officials' promises to improve mass transit.

Now that the light rail is here, county officials are expecting another 60,000 jobs in the next five years as six office towers rise in Jersey City alone. In addition, the county expects another 40,000 new housing units, 43 million square feet of office space and 3.5 million square feet of retail space in the next decade.

But all that growth, combined with the congestion created by the Holland and Lincoln tunnels, has already made the waterfront one of the most inaccessible areas in the state.

"We were getting to the choking point," Jersey City Mayor Bret Schundler said. "Jersey City has always had great location. This is finally going to allow us to take advantage of our location."

Developer Arthur Imperatore Jr., who operates the New York Waterway ferries and plans to build 6,000 condominiums and 1.5 million square feet of commercial space near the Port Imperial ferry terminal in Weehawken, said his plans wouldn't be possible without the light rail.

"The development plans preceded the light rail, but there has been enough coordination so that we've been able to plan for when the light rail gets here," Imperatore said.

The light rail's impact is already being felt in Bayonne, an old-world community where three generations of one family can be found on a single street. Though Bayonne is just four miles from downtown Jersey City, such a trip takes 40 minutes by bus or car during rush hour. That would be cut to 23 minutes on the light rail.

Jill Serafin, 28, a training and development manager in Manhattan, takes the Bayonne-Jersey City bus every day and is ready to test out the new line.

"As long as it's faster than the bus, I will definitely use it," said Serafin, a lifelong resident of Bayonne. "I think it will make it a lot easier to get in and out of the city. Hopefully it will bring new business, but we'll have to see."

Housing prices in Bayonne have already jumped 10 percent in the last year, local real estate agents said.

"I had a house sell in one day a few weeks ago for $5,000 above the asking price," said Jack Pineiro, who has been selling real estate in Bayonne for 30 years. "That never used to happen."

Upscale restaurants are beginning to move into Bayonne in anticipation of a new wave of affluent residents who have been priced out of Manhattan and an increasingly expensive and crowded Hoboken.

"I hope we become like Hoboken, just with better people," said Luis Gomez, who opened the Da Noi Italian Restaurant on Avenue C in Bayonne last month.

Jeffrey Warsh, executive director of NJ Transit, said parking and riding the light rail to Jersey City will be so much cheaper -- $5 a day to park and ride vs. $14 to park near the waterfront -- that commuters won't be able to justify passing it up.

"We're going to take in a variety of commuters with all kinds of different commuting patterns," Warsh said.

Optimism about the system will surely drop with the first system malfunctions, but for now, public officials in northern New Jersey are enamored with the image of a state filled with crisscrossing trolley lines.

They say returns will be immediate on the $1.1 billion invested in the first phase of the project opening this week. Bringing service to Hoboken by mid-2002 and to Tonnelle Avenue in Union City will cost another $1.5 billion. Extending the line to the Vince Lombardi and beyond will cost billions more.

"Getting the light rail into the Vince Lombardi (Turnpike rest area) is the number one priority for us," said Bergen County Executive William "Pat" Schuber, who wants to extend the light rail to Saddle Brook to draw in even more car-dependent commuters and spur development in the heart of Bergen County. "It's absolutely essential if we're going to continue to grow in the new economy."

Staff writer Kate Coscarelli contributed to this report.