When the giant stimulus bill, expected to be approved by Congress, finally lumbers forth it will pour billions into projects that have been neglected, like highway renovations, and items that have recently bleeped onto the public radar screen, like clean energy incentives.

In some cases, money has been included (so far) for programs that have been debated and tabled for years. High speed rail, which is slated to get $8 billion, falls into that category.

You might ask yourself, what is high speed rail? And you’d be right to ask that question, because right now, in America, there is no high-speed rail. There’s a grand plan for a high-speed train that would run the length of California, where voters last fall approved the first bond money for the Sacramento to San Diego line. Once, years ago, people proposed high-speed rail as a way to better connect Dallas, Austin and Houston, a plan that met an early death in a state well-served by airlines and enamored of highways.

Today, in Chicago, the Midwest High Speed Rail Association (MHSRA) survives, clinging tenaciously to the concept that super-fast trains can be an environmental and social game-changer in the United States and that Chicago, a giant intersection of freight and passenger rail lines, would be an excellent nexus for a high speed rail system.

America is “beyond ready for this,” says Rick Harnish, executive director of the MHSRA. “Everywhere that decent train service has been built in the last 15 years has been tremendously successful.”

Even where rail has been badly designed – Harnish named a certain line in a large metropolitan area that placed stations at noisy freeway interchanges and chose a route that didn’t make complete sense – the trains are packed, he says.

Same for Amtrak, he added, which since gasoline prices began their jittery ways, has seen its ridership climb.

Considered to be underfunded by advocates, Amtrak has won passengers despite operating on a patchwork of rail that includes sharing lines with freight routes, which contributes to delays and constrains scheduling. It achieved record ridership in 2008, carrying 28.7 million passengers.

A good high-speed rail system, says Harnish, would lift rail out of its second-class existence as an alternative to planes and automobiles and make it competitive. Suddenly it would be affordable and convenient to take the train.

At speeds of 150 to 200 miles per hour, high-speed rail could deliver passengers from Chicago to Minneapolis, or from Chicago to St. Louis, or from Pittsburgh to New York City in under three hours, or even less than two hours.

Business and social trips that were onerous by car or required expensive airfare would be suddenly doable.

Despite the derailing economy, California voters got on board for reviving train service in their state November 4th by passing state proposition 1A — a $10 million bond to begin construction of a fully electric rail system running 220-mph trains between San Francisco’s Transbay Terminal and Union Station in Los Angeles.

The bond is a vote of confidence from the public and a down payment on the $40 billion-plus project that plans to run high-speed trains from Sacramento to San Diego. The plan’s boosters say it will create jobs, relieve air and highway congestion, and help the state meet its legislative mandate to reduce greenhouse gas emissions to 30 percent below 1990 levels by 2020 and 80 percent below 1990 levels by 2050.

Slideshow: California’s High-Speed Railway Plan

While detractors like the San Diego Union-Tribune’s editorial board said California’s budget woes make spending billions of dollars on a massive transportation project not only ill-advised, but “potentially the biggest boondoggle in California history”, proponents called the victory a landmark for high-speed rail nationwide.

Amtrak spokesperson Vernae Graham said Amtrak, which supports the plan, is likely to benefit from the high-speed rail project’s test track, which she said could increase Amtrak’s track speed through California’s Central Valley. In the past year, Amtrak has seen ridership grow more than 30 percent over the Capitol Corridor – one of its Northern California routes – and achieve double-digit growth on two other California routes that stand to connect up with the high-speed trains. Amtrak’s Pacific Surfliner from Los Angeles to San Diego, the second most popular train in the entire Amtrak system, carries more than 2.5 million people a year.

According to the California High Speed Rail Authority’s business plan, the $33 billion cost of that San Francisco to Los Angeles backbone link will be shared among the State of California, the federal government, local and regional governments and private sector investors. The $10 billion down payment passed by voters to develop the system cannot be spent until matching federal, local and private funding is also secured.

It’s no surprise this plan could give fiscal conservatives, and even fiscal realists, pause in a state that just completed the longest state budget impasse in history. But on this one, former Massachusetts governor, presidential candidate and Amtrak board member Michael Dukakis told Wired Magazine, “people are way ahead of the government. They want a rail system that works.”

There’s no doubt electric rail is greener than just about any transportation alternative for the routes in question. “I don’t know of any transportation system which matches high-speed rail for reducing tainted emissions, improving air quality, and reducing dependence on foreign oil,” said Judge Quentin Kopp, chair of the California High Speed Rail Authority and chief spokesman of the campaign to pass the transportation bill.

But how quantifiably green is the project? Kopp said by the time the entire 800-mile system is completed, it will reduce the state’s reliance on fossil fuel by 12.7 million barrels of oil per year and reduce the state’s CO2 emissions by about 12 million pounds annually. And energy consultant Navigant Consulting Inc. said the train system could run with zero emissions if renewable-energy sources are used to power it. The system is expected to use 3,380 Gigawatt hours a year of energy to transport 94 million passengers by 2030. According to Navigant’s findings, generating this amount of energy from renewable sources is “well within the capabilities of the state.” This amount represents one percent of the state’s electrical load, or about three and a half days worth of electricity consumed throughout the state.

The California High-Speed Rail Authority’s business plan calculates high-speed trains will “alleviate the need to spend nearly $100 billion to build about 3,000 miles of new freeway plus five airport runways and 90 departure gates over the next two decades,” Quentin Kopp said.

High-speed rail could not only take a few polluting airliners’ out of California’s skies. It could also help airlines focus on what they do best: long-distance flights. That’s according to Robert Crandall, the Former Chairman, President and CEO of AMR Corp., the parent company of American Airlines. Crandall said in a speech to the Wings Club in June 2008 that short-haul flights of less than 300 miles, which are not generally profitable for airlines, could be readily replaced by high-speed rail. Crandall said high-speed rail and aviation could work together. “We could increase long-haul aviation capacity to and from our major cities by linking nearby airports to those cities with high-speed rail links,” Crandall said.

It’s refreshing in these days of gas and environmental calamities, not to mention lending and budget crises, to hear about something that’s chugging along in a positive direction.

That’s the story of Amtrak, or nearly so, at this junction. Ridership on the American passenger rail service is up a healthy 14 percent compared to this time last year, and is on pace to hit an all-time annual record of 28 million passengers in fiscal 2008.

Trains are whisking folks around in the busiest “Northeast Corridor” (DC to Boston) faster than ever, and people across the nation are flocking to inter-city train travel, a mode of transportation less polluting per passenger than both cars and planes. Amtrak seems right for the times and primed for expansion.

“Ridership is through the roof! Let’s get on with it,” announced Amtrak CEO Alexander Kummant at a transportation summit in Irving, Texas, last week, where he came well prepared to make the case for more Amtrak.

Tossing up a series of charts and graphs during a presentation to fellow transportation officials and business leaders, he showed the audience that train travel spirals upward in an almost dead even correlation with gas prices. Yes, our pain is Amtrak’s gain, and one can reasonably conclude that if high gas prices stick with us, as predicted, train ridership will boom.

And as more people wiggle out of their personal gasoline predicaments, trains could become ever more popular, given the leap to trains preceded gasoline hitting $4 a gallon, Kummant noted.

Furthermore, a review of the ridership shows that it is not just straining the tracks in the busy rail-savvy “Northeast Corridor,” but has increased nearly everywhere. July 2008 ridership figures show increases over July 2007 for the Texas Eagle’s San Antonio to Chicago route (up 30 percent); the Coast Starlight (Seattle to Los Angeles; up 28 percent); the Kansas City to St. Louis route (up 57 percent); and the Hiawatha (Chicago to Milwaukee; up 38 percent).

So it’s all good. Except that it’s not: Amtrak’s trains are full, but the national network is unprepared to handle more passengers.

Chronically under-funded to the point of near insolvency a few years ago, Amtrak is reaching a tipping point where it cannot take on new business because it lacks reserve cars to pull on line and also is hemmed in by lines it shares with freight trains.

Operating under tight budgets for years, and jeered by perennial critics who argue that the national train system (which traditionally operates in the red) should not even receive subsidies, Amtrak has been unable to refurbish retired cars or build new ones. The service’s infrastructure, including the depots and track that it largely shares with commercial railroads, badly needs modernizing. Many supporters believe that “double track” routes should be installed to allow Amtrak the ability to expand alongside existing lines and provide more flexible, rider-friendly service, but these lines would be expensive and subject to high local taxes.

And so, just as the demand for rail travel, ridership and gas prices conspire to create what Kummant terms a “perfect storm” of opportunity for Amtrak, the doppelganger of Amtrak Past haunts the future.

How to change that picture? Kummant cites one thing as absolutely necessary, both in his speech to transportation officials and in remarks afterward. He would desperately like Congress to give Amtrak multi-year funding, instead of piecemeal year-by-year appropriations, so it can hire, plan and strategize like any other business.

His ask is moderate compared to funding for other transportation: $1 billion a year for each of the next 10 years.

He asked this year, but was denied. “A bitter pill,” he says, in face of the potential.

“It’s incredibly easy to argue that Amtrak should double in size over the next 10 years, given everything that’s going on,” he says.

And possibly incredibly hard to make that happen. Whether Congress is letting American train potential go unrealized because it doesn’t care, is procedurally balled up (Kummant’s view) or is just better geared to subsidizing plane and car travel, has become almost academic. The bottom line is that public policy since Amtrak’s inception in 1970 is clear, the system is on a short leash — or as its supporters see it, riding a vicious cycle of too-little funding that causes it to be less profitable, which creates an argument for less funding.