Technology is helping companies and the government drag carpools -- and Washington's commuting slug lines -- into the 21st century.

A new concept -- called real-time ridesharing -- allows riders to use a smartphone app to find all the drivers already heading their way and ask for a ride in exchange for gas money. And instead of handing over cash, riders can pay drivers online through one of the new websites targeting the commuter market.

Carpooling.com, due to launch in the D.C. area this year, will use the new carpool techniques in combination with a website that lets riders and drivers view the other's online profile to help them choose people with whom they can share the commute.

"A lot of people hesitate to carpool because of issues with safety or riding with a stranger," said Carpooling.com spokeswoman Sharon Chai. With this site, "you know who you're riding with, and you know who's riding in your car."

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Carpooling in Northern Virginia is also getting a boost from a regional agency whose pilot program will offer this summer to pay workers driving to specific military facilities.

The Northern Virginia Regional Commission's $600,000 program would pay drivers $25 per month for gas and compensate them based on their mileage if they'll give other commuters a lift to those facilities.

About 11 percent of the region's work force already carpools, according to the Metropolitan Washington Council of Governments, which offers a ride-matching database for traditional car and vanpools.

But the websites and phone apps that allow carpoolers to connect with each other immediately make traveling simpler for both drivers and passengers, advocates said. The new method is similar to slugging, the unplanned Washington phenomenon in which drivers pick up riders along Interstate 95 so they can take the faster, high-occupancy lanes into the city.

But the new ridesharing systems have their flaws. To work, they require a lot of people to sign up.

"It's very difficult to do because you need someone going past your origin to your destination by the time you're leaving," said Steven Schoeffler, CEO of eRideshare.com, the largest traditional ride-matching site in the U.S. "That requires a really large critical mass, and that's hard to do. So I kind of expect that it's going to take a while to get off the ground."

Slug driver Matthew Hess said it wouldn't be worth it for him to pick up riders at their homes, instead of at slug parking lots, even if they paid for gas.

"I think the whole point of slugging is you're sharing the ride. If the person's driving, they have to drive there anyway," he said.

lessley@washingtonexaminer.com