But will it stick?

In ways America's transportation grid has not seen in a generation, people are changing their commutes. It may be a small percentage off the roads —- Ga. 400 toll traffic fell about 5 percent from April to May —- but relatively speaking that translates into a huge jump in alternative commutes.

That goes even for Georgia drivers, who in postwar decades developed a famous love affair with their cars but are now car pooling, van pooling, riding express buses or setting up shop in the spare room at home in record numbers.

From all appearances, $4 gas was the mark where they stopped to think and even pocket the car keys.

So will the change last?

It depends, experts say, and a lot of it depends on gas prices.

In the regular course of things, about 64 percent of people who sign up for $3-a-day rewards offered by the Clean Air Campaign for switching to greener commutes end up sticking with the change for a year or more, said Kevin Green, executive director of the campaign. A New Jersey incentive program found a similar stick-to-it rate, 68 percent, and almost all Houston van poolers surveyed said they'd stay with their van pools.

But these are not ordinary times, and it's hard to say what would happen if these Everest-like gas prices fell back down. Commuters who've switched gave mixed reviews in interviews.

Robert Thibault, a project manager for Turner Broadcasting who's taking MARTA, said $2 gas would probably entice him back to his car because of "the convenience of being able to get virtually anywhere that I want to get at any time I want to." But on second thought, he said, "I'd have to rethink it, because my whole mind-set about taking the train has changed. It is not as inconvenient as I thought it would be."

So what will happen with gas prices?

They're going down, said James Williams, an energy economist in Arkansas and owner of wtrg.com, an energy research Web site, because a global recession will drag down demand and then someone will invent a battery that will sweep the country and drag down oil demand more.

They're going up, way up, said Douglas Reynolds, a resource economist at the University of Alaska, because we're using more oil than we're finding, and China's growth will be so strong that demand will continue to rise.

In short, there's no crystal ball. Except the one that says: Pity the poor wallets.

METRO ATLANTA UNLEADED GAS

Jan. 1: $2.98

Feb. 1: $2.93

March 1: $3.15

April 1: $3.25

May 1: $3.62

June 1: $3.98

June 8: $4.01

Source: AAA

MANY OPTIONS EXIST

CAR POOLING

> Snapshot: Atlanta Regional Commission ride-share database (www.myridesmart.com)

> Up 221 percent: Applications received in May 2007 vs. May 2008. May also be matched to van pools.

"That's awesome," said Jane Hayse, the ARC's transportation planning chief. "Typically, car pooling has been a lot of family members, the easy car pools," which usually doesn't get cars off roads and isn't what government had in mind in creating HOV lanes.

"Now I think we're getting at folks trying to find individuals traveling the same place at the same time."

MARTA

> Up 15 percent: train ridership April/May 2008 over April/May 2007

> Up 7 percent: Entire system including buses.

The people who have always had the option to ride transit may be more likely to make the jump for a train than a local bus, at least where bus service isn't as frequent and well-funded as the trains.

"Newcomers to transit may be those traveling longer distances," said Jane Hayse, transportation planning chief of the Atlanta Regional Commission.

Gas prices brought Brenda Brown, a health administrator, to a MARTA bus and train two months ago.

"Four dollars," she said. "That was the moment."

TELECOMMUTING

> Snapshot: Clean Air Campaign commuter rewards registrations

> Up 23 percent*: Teleworkers registered for the CAC's $3-a-day commute-change promotions in May 2008 vs. May 2007.

When Gary Hu changed jobs in October, he quit teleworking. Gas prices brought him back and eased the way with his employer to telework once a week, he said.

*These totals are only 13 teleworkers for May 2007 and 16 for May 2008. The CAC said its database underreports teleworkers because it doesn't show teleworkers who register for more than one commute option.

VAN POOL

> Snapshot: Douglas County Rideshare

> Up 160 percent: Revenues from May 2008 over May 2007

The program is filling empty seats and adding new routes, with destinations ranging from downtown Atlanta to other metro suburbs. On June 2, "We just started a new route that goes to the federal prison in Talladega, Ala., which is a 170-mile daily round trip," said Gary Watson, the county's ride-share director. It's already full.

EXPRESS BUS

> Snapshot: Georgia Regional Transportation Authority

> Up 67 percent: Ridership for May 2008 over May 2007

"I was tired of the gas, tired of being drained when I came home from work," said David Holmes, a bus commuter from Woodstock to downtown Atlanta who quit his solo drive in January. He said it doesn't matter whether gas drops to $2, "I'm not going to change [back]."

For Frank Casagrande, who started taking the Woodstock bus to Atlanta three weeks ago, it wasn't gas prices so much as congestion.

"I don't know what I was thinking driving my car in traffic all this time," he said. He said it doesn't matter what happens with gas prices, he's not going back to his car. One thing Casagrande has noticed in his three weeks on the bus —- it's gotten so crowded.

"Last Thursday I was going back home on the bus, and when we got to the last stop somebody sat down in the last available seat. If one more person had gotten on the bus, it was standing room only."

LOCAL TRANSIT

> Snapshot: Gwinnett County Transit

> Down 20 percent: Boardings from May 2007 to March 2008

> Up 17 percent: Boardings from March 2008 to May 2008

"The downtrend in the economy really affected local ridership," said Phil Boyd, Gwinnett County's transit director.

"I think people lost their jobs, and also the ones that still have jobs were [feeling] money was tight and they were making less nonwork trips." But gas prices are apparently changing that.

"What's interesting about the gas price run-up is, if you look at it for past three months, [it] has reversed that trend."

NATIONWIDE

> Driving: Down 30 billion miles

Six months ending April '08 vs. six months ending April '07

Source: U.S. Department of Transportation

> Transit ridership: Up 85 million trips

1st quarter of 2008 vs. 1st quarter of 2007

Source: American Public Transportation Association

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Data Sources: Douglas County Rideshare, GRTA, Gwinnett County Transit, MARTA, ARC, Clean Air Campaign, Federal Highway Administration, American Public Transportation Association, AAA. Moshe Ben-Akiva and Takayuki Morikawa of the Massachusetts Institute of Technology and Nagoya University