WASHINGTON -- Many drivers are responding to increasing gas prices by joining vanpools and carpools.

Sandy Silzer took over the wheel of a 12-person van about five years ago. At 6:10 a.m. each day, she and her passengers begin the drive from Loudoun County into federal government offices in the District. She said it used to be hard to get enough people to fill all the seats, but now there is plenty of interest. Silzer said she has a waiting list and is considering upgrading to a 15-person van.

Silzer's monthly charge of $180 a month is increasing to $200, but her riders told News4 it's still a deal with gas prices above $4 per gallon.

The recent surge in carpool interest is keeping the staff busy at the downtown office of Commuter Connections, a carpool matching service.

"People who are driving by themselves are looking to make a change due to gasoline prices, and it kind of caught us by surprise," said director Nicholas Ramfos.

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Applications in May were up 48 percent from May 2007, and from April to May, they jumped by 22 percent. In a single day last week, they received 250 applications. In spite of the sudden demand the carpool matchmakers said they are keeping up with requests.

Many commuters are turning to informal slug lines. Those who don't want to drive line up and wait for drivers looking for bodies to fill their seats so they can take high-occupancy vehicle lanes for quicker commutes.

Commuters told News4 that they've noticed an increase in slug lines. Tim Pemberton said he also noticed an increase in the lines last year when gas prices were fast increasing. He became a rider last year. He said as a driver, he has no trouble finding riders this year.