ATLANTA -- In a city overrun with interstate highways and clouded in smog, the workday never ends at 5 p.m.

For Atlanta's car-bound commuters, leaving the office is just when tension begins to build. Stress levels rise in the race to get home -- to get off the maze of roads that crisscross the suburbs; to turn off the radio and its nonstop traffic reports; to pull into the garage, turn off the engine and savor the time left before the rush-hour routine will have to be repeated the next morning.

Of course, bumper-to-bumper traffic is hardly unique to Atlanta. Drivers in Washington, New York, Los Angeles and elsewhere share similar headaches. But here, sidewalks are afterthoughts in urban planning, and the skeletal subway system is just beginning to gain popularity. Pollution is so heavy that the federal government two years ago barred the 13-county metropolitan area from building new highways until it met national emission standards.

Traffic seems to be Atlanta's trademark, rivaling even Coca-Cola and media mogul Ted Turner. And for years, there were few plans to change.

Enter PATH, a 9-year-old organization that since 1996 has pushed the city to fully adopt its Greenway Trail Corridor Plan.

Spearheaded by an Atlanta native named Ed McBrayer, the proposal would bring 110 miles of trails through the city, partially converting three of Atlanta's most underused multilane boulevards into paths. Half the original lanes would still be used by cars, but the other half would become a shaded, tree-lined, 14-foot-wide concrete path for cyclists, walkers and roller-bladers.

"We want to create a network of trails that connect all the places where people need to go," says McBrayer, sitting in a West Peachtree Street office blanketed with poster-size maps of potential trail routes. "We want to give people an option to cranking up the car so that we can make this a more livable city."

It's an ambitious plan. McBrayer hopes one day to link the city's neighborhoods using designated bicycle lanes on roads, in combination with shorter paths that would run alongside golf courses, parks, cemeteries and other available green spaces.

PATH's plan would build on a smaller intracity trail system begun before the 1996 Olympics. The finished system could link Atlanta to a network of trails across the state, like the partially completed Silver Comet Trail, which begins in Smyrna, just west of the city, and will extend to Birmingham, Ala., by 2002.

"It's a lot of work, but it's worth the time and effort to make Atlanta a bicycle-friendly city," McBrayer says.

It isn't just the scope of the plans that distinguishes PATH's proposals. Denver, for example, boasts a 120-mile trail system used by daily commuters and weekend cyclists. Similarly extensive dual-purpose bike routes have been integrated retroactively into Seattle, Portland, Philadelphia, Miami, Chicago -- even automobile-obsessed Los Angeles.

In most cases though, those trail-equipped cities had at least one of two factors working in their favor: a long tradition of cycling as a means of transportation or plenty of green space, such as a riverfront or abandoned railroad, where paths could be built.

Some are blessed with grid-based street design; straightforward intersections and short blocks make for slower driving and safer biking. All have a population of motorists used to treating cyclists as commuting partners.

Atlanta has no such advantages. That makes it especially difficult, transportation experts say, to integrate bike routes with main roads and into the normal flow of traffic. What the city is attempting, they say, is without precedent.

"Atlanta exemplifies the problems that any urban area could face, but Atlanta has them all and in a far greater concentration than most," says Andy Clark, executive director of the Association of Pedestrian and Bicycle Professionals. "A city like Atlanta is a big ship to turn."

What Atlanta does have is a compelling motivation: Until the city produces a transportation plan that meets national emission standards, the federal government will maintain the freeze on highway building in Atlanta.

"The money that would have gone to build roads can now help increase bike facilities," says Pam Bobe of the Atlanta Bicycle Campaign, which has asked the city to designate lanes on some of Atlanta's main arteries for bikers. "It doesn't take much to restripe a road. It's a cost-effective way to use this money."

Bicycle-advocacy groups also have on their side the Georgia Regional Transportation Authority, a 15-member board created in June by Gov. Roy Barnes to oversee transportation plans for the area. The group has met formally only twice so far, but it has been praised by trail advocates for its nonpartisan nature and its sweeping authority to finalize regional plans.

"It took a crisis to get us to the point of acting, but now we're ready to act," says Charles Walston, a spokesman for the authority.

Already, the transportation authority's three-year, $1.5 billion budget allots 7 percent of its federal and state funding to bicycle and pedestrian facilities. That might not sound like much -- especially compared with the 42 percent to be spent on road maintenance. But just a few years ago, Walston suggests, bike and pedestrian facilities would have received a much smaller piece of the pie.

Yet, can a city raised on the almighty automobile trade it in for a 10-speed? If they build the trails, will the people ride?

Twelve years ago, Paul Kelman would have said no. The vice president of Central Atlanta Progress, a nonprofit business group, Kelman was also the architect of a trail system proposed for the city in 1987.

"It was good work, and for a while it was applauded," he says. "Then it was roundly ignored. It just wasn't the right time."

But now, Central Atlanta Progress has included bicycle facilities in its most recent plans for a transportation study of the downtown area. And Bobe says members of the Atlanta Bicycle Campaign are no longer referred to by critics as the Atlanta Bicycle Crazies. The group boasts 1,000 members, many of whom belong to neighborhood bicycle-user groups that teach safety and promote cycling as both transportation and recreation.

Nationwide, more than 5.5 million people call themselves avid cyclists, more than ever before, according to national bicycle-advocacy groups, and the heightened interest among Atlantans, regional groups say, reflects this trend.

Nevertheless, few of the bike enthusiasts are crazy enough to expect the advent of widespread trails to put a deep dent in Atlanta's traffic congestion.

Kelman points out that it took 30 years of rapid development to create the environmentalist's nightmare that Atlanta has become. Persuading a few commuters to bike to work won't make that much of a difference -- at least not in the short term.

"Scientifically, I doubt we are going to significantly decrease pollution," Kelman says. "But maybe you can change people's mode of thinking so they can say, 'Well, he's riding a bike, so maybe I'll take transit.' Maybe over the long term, you can have an impact."