When the sunset-hued Golden Gate Bridge first opened more than 75 years ago, it was the engineering marvel of its time. Just north of San Francisco's famed bridge lies an equally impressive transportation corridor for a new era. When complete, the aptly named SMART Pathway (Foss Creek SMART Pathway, Petaluma SMART Pathway, Rohnert Park/Cotati SMART Pathway, Santa Rosa SMART Pathway, Novato Downtown SMART Pathway) will include the most miles of bike and pedestrian trail alongside active railroad, 52, in the country.

Though rail-with-trails are not a new idea—Rails-to-Trails Conservancy (RTC) first reported on them in 1996—they are catching on as a way to create new transportation options in an increasingly constrained urban environment. Today, there are 168 rail-with-trails around the country, a whopping increase of more than 400 percent since RTC's first report on these projects nearly two decades ago. An updated rail-with-trail report will be published this fall.

"We're building it in the railroad right-of-way and the edge of the trail is pretty close to the tracks," says Paul Klassen, project manager for the SMART Pathway. "Mostly it's 10 to 15 feet away, though in some places it's 100 feet away."

The scope of the project is massive. The Sonoma-Marin Area Rail Transit (SMART) commuter rail line and parallel pathway will stretch 70 miles between Cloverdale and Larkspur. This dual transportation system will connect 14 train stations and 10 cities across two counties.

"The pathway goes through a lot of historical main street areas," says John Nemeth, planning manager for the SMART District, which oversees the effort. "It alternates between open space and downtowns, so you can get on and off, and have lunch or go shopping. It's a town and country experience."

The Marin County Bicycle Coalition has been involved with the pathway since the idea was first conceived in the late 1990s. Its advocacy director, Andy Peri, says the pathway will "create an infinite number of connections. These towns formed along the old rail line. These are population centers with shopping, work places, and schools."

While the area's rugged hills offer a splendid natural backdrop and a wealth of recreational opportunities—the mountain bike was invented here in the 1970s—they restrict transportation options. "The rail-with-trail project follows Highway 101, which is the only north-south route through Marin County, so it gets quite congested," says Barry Bergman, manager of trail development at RTC's Western Office.

When traffic backs up, there are no alternative routes for commuters. Originally, only passenger rail service was planned to address the situation, but at the urging of county bicycle coalitions and other advocates, an adjacent pathway was added to the project. "We needed to alleviate congestion through multiple options," says Carolyn Glendening, SMART's community education and outreach coordinator. "Working in synergy held more promise than either option alone."

At first, it took some persuading to get everyone on board with the pathway concept, but the project is well underway now. "It had to go through many levels of approval," says Peri. "Environmental, legislative, funding… and, at every stage, the pathway was in jeopardy. You're never done until you're riding the path."

A boost for the effort came in 2008, when a quarter-cent sales tax increase to fund both the rail and the trail was put to voters in Marin and Sonoma counties. A two-thirds supermajority was needed for its passage, and, in the end, nearly 70 percent of voters approved.

But the bloom fell off the rose as the recession hit soon after. "The sales tax money dropped off because of the economy," says Gary Helfrich, executive director for the Sonoma County Bicycle Coalition. "So we had to consider where most people live, and develop that section first. Phase 1 will go from Santa Rosa to San Rafael—county seat to county seat—which are the two largest cities in the North Bay. Phase 2 will be the all the rest."

Of this 38.5-mile stretch, Glendening says, "Phase 1 is fully funded and under construction, starting with the rail portion. The construction contract for some Phase 1 pathway segments will be awarded in the coming months, while other sections are currently under environmental review. Some are even likely to be open and operational before the rail service starts. Beyond Phase 1, the rail and pathway will be completed as funding becomes available."

About five miles of the off-road trail are on the ground already and about a third of the on-road sections are signed and striped. Rail service is expected to begin by late 2015 or early 2016 with trains running every 30 minutes during peak weekday hours. Mid-day and weekend service will also be offered. The train cars will have room for bikes, allowing passengers to combine riding the trail and the train for recreation and commuting.

The combination of Sonoma County's scenic vineyard countryside and Marin County's craggy terrain may prove irresistible to tourists. "In Marin County, there's a huge amount of open space," says Bergman, who regularly hikes in the area with his wife. "There are redwood forests and a beautiful coastline. It's gorgeous."

The trail's most unusual feature lies on its southern end: the Cal Park Hill Tunnel, a relic of Northwestern Pacific Railroad, which was active here in the early 1900s when northern California's towering redwoods were being harvested for lumber. More than 100 years later, the SMART rail line follows that same corridor, converting the tunnel for the modern day by adding a separated trail for bicyclists and pedestrians alongside the trains.

RTC provided guidance to Marin County on the project and, inspired by the challenge, published a research report called Tunnels on Trails in 2001. The trail extends a short distance out either side of the 1,100-foot tunnel to connect San Rafael with Larkspur, where trail-goers can catch a ferry to downtown San Francisco.

"I was there for the groundbreaking of the tunnel, and this past July I had my first tour of this phenomenal facility," says Marianne Fowler, RTC's senior vice present of federal policy. "It's a key part of the bike/ped infrastructure in Marin County."

A critical piece of funding for the tunnel project was contributed by the Nonmotorized Transportation Pilot Program (NTPP), a federally-funded experiment designed to test the impact of making biking and walking infrastructure a priority of transportation planning. In 2005, Marin County was one of only four communities selected nationwide to receive a $25 million NTPP grant to develop these types of projects and report back on the changes that the investments made in travel habits and other measurable effects.

"RTC was instrumental in getting the Pilot Program included in transportation law," says Fowler. "If Marin County hadn't received that program grant, the tunnel would probably not have been built as a dual purpose, bike/ped and transit, facility."

To the north, the SMART Pathway will end at Cloverdale, which, like other small communities along the corridor, stands to gain economically from the people that the SMART system will bring. "Cloverdale is a mill town that's down on its luck," says Helfrich. "But their city council really gets it. They see this project as an enormous opportunity to reinvent themselves as a tourist mecca."

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