Nyaljor Samten, a systems engineer who carpools from El Cerrito to San Francisco, used to enjoy his morning car ride. He could nap, daydream or review e-mail. Best of all, he got to San Francisco for free.

But since the Bay Area Toll Authority began charging carpool drivers $2.50 to cross Bay Area bridges July 1, Samten is often asked to chip in money. He and many other passengers don't like that.

As a casual carpooler, Samten is part of an unofficial system in which hundreds of drivers looking to zip past traffic by using the diamond lane pick up willing, but anonymous, passengers at designated spots throughout the Bay Area.

The rules of the system have been continually negotiated by the community since the practice began in the early 1970s: Don't speak unless spoken to. Don't eat or drink without the driver's permission. Don't talk on the phone. Most important, under no circumstances are you permitted to snore if you fall asleep.

But now passengers and drivers have to settle payment of the toll, igniting passions, dividing the community and causing some to even question the value of the casual carpool in the first place.

Interviews with three dozen drivers and passengers suggest there are three camps: those who pay a share of the toll - usually $1 - no matter what, those who pay only when asked and those who refuse to contribute.

Riders' reactions vary

Any which way, it's still cheaper than the $5 to $6 non-carpool drivers are charged or the fare to ride on BART.

But Samten, 47, and a large group of East Bay commuters resent being asked for money. "We are actually giving away our right," he said, referring to submitting to the control of the driver.

"Now on top of that we are to chip in the cost for crossing the bridge at a discounted fare and in a faster lane, which drivers couldn't do without our participation," he added.

But others - many of whom commute from Solano County and the far reaches of Contra Costa County - don't think it's fair to make the driver, who already has to pay for gas and concentrate on driving, also fork over the toll.

"I feel like (contributing) is the right thing to do, for one thing," said Tom McCamy, a branch manager with a private security company who carpools from Fairfield to San Francisco. "You're getting a free ride, for crying out loud."

McCamy, 61, said that in his experience, every passenger puts in for a portion of the toll without complaint.

That's a far cry from what happens at the queue at the El Cerrito del Norte BART Station, where passengers often shop for a driver who won't require payment, said Kate McNee, 31.

"If they said they wanted us to contribute, we could just go to another car. There's a whole line of them," she said.

Drivers, for the most part, seem to set their own standards. Most appreciate, but don't require, a contribution, while others will turn off their car and sit until passengers pay up.

Spreading out the cost

John Goodwin, spokesman for the toll authority, said the purpose of the new $2.50 toll was not to discourage ride-sharing, but to spread out the cost among all drivers. The toll increase will fund seismic retrofits of the Dumbarton and Antioch bridges while also bolstering toll revenues.

"We wanted to limit the toll increase for the 90 percent of drivers who saw their toll increase by only a dollar," he said.

Still, preliminary data released in late July show that, on average, each day there are 12,000 fewer drivers using the carpool lanes on bridges throughout the Bay Area, compared with the same time last year.

Some have had enough

This decrease in available drivers, passengers say, has led to longer waits in this summer's cold, foggy weather. Add a payment - however small - and some say they have had enough.

"It is more time-saving for me now if I ride BART," Samten said. "And now, I don't have to deal with the driver."

Goodwin said the authority will work with the Institute of Transportation Studies at UC Berkeley to gauge the impact of the toll increase. But he said he hopes the casual carpool community can continue to regulate itself, as it has for decades.

"We still have no intention to weigh in," he said. "We have tremendous confidence that this community will sort it out."