To most people who live in Maine, a bus is a yellow vehicle carrying schoolchildren and a subway is a sandwich chain.

There is public transportation in Maine, according to state experts. It simply does not fit the definition more common in U.S. cities such as Boston, in which buses and trains often are within walking distance or a very short drive from people’s homes.

Much of Maine’s public transportation system operates beneath the radar, serving certain segments of the population, or only within the state’s largest cities.

The recent fluctuations in gas prices have some wondering whether improvements can be made to existing public transportation systems so those who own vehicles can leave them at home and still get to work, or at least drive less than they do now.

With 1.2 million people spread over 35,000 square miles, Maine isn’t the best candidate for a new public transportation system. But transportation planners believe tweaking existing systems and adding new components can make a difference.

David Cole, commissioner of the state Department of Transportation, said that Maine is one of the most rural states in the Northeast, with 8,300 miles of state roads. By comparison, New Hampshire, with the same population, supports 3,800 miles of state roads, he said.

Sue Moreau, a policy specialist with the DOT, said the state’s best shot at improving access to public transit is to make people aware of existing options. She includes commercial buses, trains, ferries and airplanes in a list of transportation services that are available to the public, even though they are not necessarily funded with public money.

The distinction between a municipally operated bus system such as the BAT Community Connector in Bangor and the privately owned Concord Trailways bus company is irrelevant to those who would use either or both, Moreau argued.

In fact, more people should think about Concord Trailways, Greyhound and other commercial bus lines as a way to get around within Maine, she said, rather than only as a way to get to Boston or Logan International Airport. In addition to its express buses from Bangor to Portland and Boston, Concord Trailways provides regular bus service along coastal U.S. Route 1, stopping in many towns.

Moreau also touts the Downeaster Amtrak train service from Portland to Boston, which has exceeded ridership projections and which transportation experts consider a success. Just last week, the service saw its millionth customer.

She and others also point to the successes of the Island Explorer shuttle bus system on Mount Desert Island, which carries 400,000 people to and around Acadia National Park between June and Columbus Day, and the newer versions of that concept – the Mountain Explorer in Bethel, operated with a subsidy from Sunday River ski resort, and buses that operate along the York County coast during the summer.

“We’re being creative. We’re being innovative,” Moreau said.

“And we’re being conservative. We don’t start a new system without a business plan,” she added, explaining that new systems are created only when users and funding are identified. The Island Explorer and its spinoffs are the result of private-public partnerships.

Cole echoed Moreau’s view, saying public transit enhancements must include private assistance.

“You need to customize it with partners,” he said. “We can’t engineer and build our way out of every situation. We’ve got to innovate. We need to augment the vehicle, not replace it.”

While the tourist-related systems work well, what about a Mainer who wants to drive part of the way to work and car-pool the rest of the way?

Moreau points to DOT’s GoMaine.org Web site, which allows users to register to be linked with neighbors who commute to the same town or city for work. Approximately 5,000 are registered in the site’s database, she said.

The DOT also established 40 park-and-ride lots, totaling more than 1,000 parking spaces, to make it possible for people to carpool more easily. About 360 car pools have registered with the DOT, which wins them preferential parking. Less formal car pools are welcome to use the lots, too.

A van pool, with 18 vehicles, has operated for more than 20 years between Portland, Lewiston-Auburn and Augusta, Moreau said. Approximately 150 residents pay the $100 monthly fee, and leave their cars parked nearer home.

“It’s a very good program,” Moreau said.

DOT’s ExploreMaine.org is another resource, handling more than 48,000 requests for information last month about public and private transportation options ranging from aircraft to bicycles.

Moreau believes the state’s role is to market existing systems and educate the public about their benefits.

Municipally run bus systems operating in the larger cities of Portland, South Portland, Lewiston-Auburn, Augusta and Bangor are considered part of the overall public transportation picture. Those systems have to be rethought, marketed and tweaked to maximize their use, transportation planners say.

Steve Linnell, senior transportation planner for the Greater Portland Council of Governments, said that Portland’s Metro, which is funded by federal transit money and by municipal funding from Portland and Westbrook, is succeeding in attracting users.

A key element is to make the service regular, he said. People won’t use buses if they can’t predict when one will arrive.

In recent years, the Metro service reduced the waiting time on many of its runs from 30 minutes to 15 minutes, which in turn increased total ridership by 40 percent, Linnell said.

Expanding bus service up the Route 1 corridor might make sense, he said, but “it has to be done very thoughtfully.”

Early in the 20th century, trolleys ran along parts of Route 1, trains were geared toward passenger service, steamboats were a fixture in most coastal towns, and systems connected, “so you could go anywhere.” A return to that is possible but would be difficult, he said.

Expanding Amtrak service north to Brunswick is six to eight years away, most agree, and will take even longer to connect to Rockland.

Linnell is skeptical about whether people experiencing gas price shock will make permanent changes.

“The choices we’ve made essentially tie us to our cars,” he said. Land use decisions, “where we choose to work and play,” often put people far from public transportation. The cost of gas is part of the cost of sprawl, he suggested.

“I’m kind of glad [gas prices] caught people’s attention,” Linnell said. “[But] if the price goes down, they’re all going to get back in their cars.”

Tom Crikelair, a transit planner and consultant from Bar Harbor who designed the Island Explorer system and its spinoffs, agreed that public transportation must be carefully considered before being expanded.

Before running buses along Route 1, for example, he said a study should determine who would use that kind of transportation and how much users would pay.

“You can’t just put buses out on the street and expect people to ride them,” he said.

A private vehicle “is a formidable product to compete with,” he said, but sometimes education can be an ally.

In August, for example, a driver in his own car leaving Bar Harbor would arrive at Jordan Pond before someone riding the Island Explorer, but the bus rider would be on a carriage trail hiking while the car driver was searching for a parking space. Persuading park users such rhetoric is true has been essential to the success of the Island Explorer, he said.

Chris Hall, a former state senator and representative who works with Stafford Business Advisors, a consulting firm that deals with transportation issues, thinks planning should focus on “connecting the dots” of smaller systems.

“I think the key word is ‘connectivity.’ It’s hard to connect those dots in the absence of a well-developed rail network,” he said.

Using existing rail corridors to connect residential areas to job centers, like Bangor and Brewer, for instance, makes sense, he said.

Like Linnell, Hall believes the public must understand the true cost of sprawl, and that investing in public transit will show a return over the long term.

“So much of this comes down to what we are willing to subsidize. I-95 doesn’t make a profit, either,” Hall said to critics of the Amtrak and other subsidized services.

Matt Robison, who serves on U.S. Rep. Mike Michaud’s staff, said most federal funding for public transportation is linked to reducing traffic congestion and poor air quality. Northern and eastern Maine has little of the first, though some of the second, he said.

Some funding in the federal transportation bill has been dedicated to helping people commute from rural areas in northern Maine to jobs in Bangor and elsewhere, Robison said.

One kind of public transportation that has quietly functioned for decades in Maine is the on-demand system, often operated by private nonprofit social service agencies for low-income, disabled and elderly people. Those systems use regular bus runs and volunteer drivers who respond to calls and are reimbursed at a per-mile rate.

With the recent fluctuations in gas prices, many volunteer drivers are dropping out, social service agencies report.

The Aroostook Regional Transportation System operates 16 passenger buses, carrying people from outlying towns such as Mars Hill and Ashland to the service center of Presque Isle for shopping and appointments, said Executive Director Dan Donovan.

Last year, the buses throughout The County carried 55,877 passengers and covered 774,839 miles, Donovan reported. Many ride the bus for free, with the cost reimbursed under MaineCare, or pay a nominal amount.

The buses can be used by anyone heading in the same direction for a flat fee of $3.50, Donovan said.

While the system is serving a substantial number of people, the schedule would not work as an alternative mode for working people. Generally, the buses run from 10 a.m. to 4 p.m., he said, and trips originate in a particular town one day a week.

In the 1980s, the agency operated a worker-oriented bus service, Donovan said, but interest waned when gas prices moderated.

Regardless of the tendency of gas prices to go up and down, Maine’s transportation leaders already are taking stock of what the state offers its residents for public transit and are thinking about ways to tie independent systems together more efficiently. So although residents may never see mass transit in Maine, state planners believe that through small, incremental steps more residents could have increased access to transportation alternatives.