The parking lot at PATCO's Westmont station, where Sam Spanier used to find a spot with no problem, was again full yesterday.

The same situation faced Tara Smith, who commutes to Center City from Delaware on SEPTA's R2 line.

For many regular rail commuters, the first sign that their ranks are growing thanks to $4-a-gallon gas is that the walk from their cars to the station also has increased.

Spurred largely by soaring fuel prices, ridership on commuter rail lines is up here and around the country.

On SEPTA Regional Rail, there have been 2.8 million more trips, or an 11 percent increase, over the last fiscal year. And on the 14-mile PATCO High-Speed Line, average weekday ridership is 35,138, up from nearly 33,000 a year ago.

For some riders, that means finding a seat also might be problem.

John Kopesky, a lawyer who makes his way to Center City on SEPTA's R6 from Norristown's Elm Street Station, said parking has not been a problem for him because he takes the first or second train in the morning.

But, he said, he has noticed that as soon as the train crosses into the cheaper inner zone, ridership soars.

"It's been a very gradual buildup," Kopesky said. "But now, there are always large numbers of people waiting to get on the train at East Falls.

"East Falls is the point where my train hits standing room. We never had standing room on my train."

Although Spanier, 25, a social worker, had to park in an outer lot yesterday, his 8:30 a.m. trip from Westmont to 10th and Locust Streets was not as crowded as it has been on some other mornings.

One factor was that the train before his was an express between Woodcrest and Ferry Avenue. Then there was the possibility the stifling heat prompted some rail riders to forget the cost and drive to work in air-conditoned vehicles.

Still, Spanier said, there have been days when he has had to stand.

"The trains are definitely filling up," he said. "But it hasn't gotten to the point where people are on top of each other."

"It has to be the cost of gas," he said.

Smith, 23, who works with Spanier, commutes into the city two or three times a week from Churchman's Crossing in Delaware, the second northbound stop on the R2.

"Parking there is separated into two different lots," she said. "I've figured out that if I come at the same time I usually do, I'm automatically pushed back into the second lot.

"I also really noticed it because there are more people standing on the train, which didn't happen before at all, hardly," Smith said. "By the time we cross into Pennsylvania, people are sometimes standing. That stinks for them."

"It started to pick up in mid-May and it's been pretty consistent," she said. "I've considered starting later, and I also do try and work from home a little more, instead of coming in here."

Contact staff writer Joseph Gambardello at 215-854-2153 or jgambardello@phillynews.com.