Think of all those empty seats in cars headed to school or work in cities around the world. The idea that filling them is a communal good goes back at least to World War II, when the Office of Price Administration put out a poster proclaiming, “When You Ride ALONE You Ride With Hitler!”

National Archives and Records Administration

As carpooling started to wane — the Census Bureau estimates that 11 percent of workers carpool now, down from 23.5 percent in 1980 — other variants emerged.

One was “slugging,” or “casual carpooling,” which involved riders gathering at conveniently located spots and drivers picking up those who are going their way. It has been popular in the Washington and San Francisco Bay areas, which nonetheless rank No. 2 and No. 6 on the most-congested list.

The rise of cellphones and now smartphones has brought a whole new dimension to the process. Piggybacking on the casual-carpool model, Web sites and smartphone apps have been creating virtual gathering spots to match drivers and passengers.

One of the first was NuRide, which was founded in 2002 and went live online in 2005. As Bloomberg Businessweek noted, it has 300 sponsors and nearly 50,000 members in four states and the District of Columbia. Many join through their employers or through a university — SUNY in Orange County, N.Y., participates, as does the University of Virginia. Houston and San Antonio are NuRide cities; a trial is rolling out in Austin.

The lure, aside from a free ride?

“Reward” points that can get both rider and driver discounts on purchases with participating vendors like Chevron or local restaurants or retailers. And the rewards are not just for carpools, but for biking, walking or taking public transportation.

Then came Carticipate, an iPhone and Facebook app that allows drivers and riders to post their route and travel time; no money or rewards involved.

The latest venture is Avego, which is just unrolling its beta test in the Seattle area after talking about a launch for more than two years. It adds a new element — micropayments of 20 cents a mile for a passenger, of which the driver gets 85 percent and the company 15 percent. The driver’s share is topped off at 55 cents, the I.R.S. limit on reimbursement for noncommercial travel. Both driver and rider would have virtual wallets with Avego, which would handle the transfer.

Because of its ability to use G.P.S. coordinates of both riders and drivers, pickups can be arranged with relatively little advance planning; both parties are sent photographs of each other and the rider is given a onetime PIN number which the driver punches in to ensure the right person is climbing in.

With 20 drivers in the Seattle area, Avego has a way to go before it catches up to NuRide’s membership levels; the formal introduction of the Seattle service is planned for later this spring along Route 520, which links downtown Seattle and the University of Washington with Bellevue and Redmond, Microsoft’s base. “We’re trying to create an option for people that will become the best option for people,” said Sean O’Sullivan, the company’s founder.

It will be interesting to watch which model proves more attractive to the casual carpoolers of the future and thus helps most in taking more cars off the road.

Source: www.nytimes.com