Click here if you are having trouble viewing this gallery on a mobile device

PINOLE — After 30 years of struggle, the East Bay Regional Park District is building a $13.2 million bridge over the railroad tracks in Pinole — the agency’s priciest and most complicated trail project ever — to keep the dream alive for a continuous trail around the Bay from San Jose to San Francisco to Richmond, Oakland and Fremont.

To be completed in June, the trail link — a 1,100-foot bridge and 1,200-foot segment — will expand public access to a scenic but largely unknown stretch of coast in northeastern Contra Costa County with sweeping views of San Pablo Bay and the skylines of San Francisco and Marin counties.

The project also offers a glimpse of the difficulties ahead in completing the last 145 miles of the multi-use Bay Trail through nine counties and 47 cities.

“The easiest parts of the trail were done first. It gets harder after that,” said Sean Dougan, the trail development program manager for the East Bay Regional Park, one of many partners in the Bay Trail. “This new segment in Pinole was, without a doubt, the most expensive and complicated trail project in the 83-year history of the park system.”

Indeed. When Bay Area leaders embarked three decades ago on a 500-mile trail around the San Francisco Bay shore, they knew few places threatened to thwart the ambitious project as much as a narrow sliver of coast in Pinole where busy railroad tracks near steep bluffs left little room to carve a public path.

Geography, funding and the railroad stood in the way.

“This segment in Pinole is a good example of the challenges that lay ahead of us with the Bay Trail,” said Lee Huo, a planner with the Bay Trail Project, a nonprofit group that coordinates trail planning. “On the positive side, there are many determined organizations working on finishing this trail with the backing and strong will of the public to move this project forward.”

The new segment will close an approximately half-mile gap between Pinole Shores Regional Shoreline and the Bayfront Park.

“The views of the bay here are gorgeous,” said Colin Coffey, a regional park board member from Hercules on a recent visit to the construction site.

Diving ducks waded nearby in shoreline marshes, and vast expanses of the gray waters of the bay stretched out toward the horizon which was filled with billowing clouds on a rainy day.

“We expect this to be very popular with cyclists and hikers, including local people and visitors from some distance away,” Coffey said.

He predicted the trail link will be more popular than ever to cyclists when Hercules opens an intermodal transportation center enabling bicyclists to hop off the train in Hercules and pedal along the Bay Trail.

The Pinole geography, however, is formidable to trail makers. Active Union Pacific railroad tracks take up most of the narrow space between San Pablo Bay and the steep bluffs above the shoreline. Houses are perched on the top of some of those bluffs, while other sections are open area linked with oak and bay forests.

“This is a hard trail gap to close, but the park district had the foresight and resources to work on it for decades,” Coffey said. “If we didn’t do it now, I doubt this gap in the trail would ever get done, and we’d have a hole in our dream to have a continuous trail around the Bay.”

Railroad officials, worried about people being run over by trains, were reluctant to have a public trail with hikers, skaters, strollers and cyclists anywhere near the busy tracks.

The park district, however, didn’t quit. The agency intervened in the federal review of a railroad merger in 1996 and secured a requirement that Union Pacific provide public access improvements to the shoreline to offset the effects of an increase in train traffic along the tracks.

The park district argued that having safe, legal ways to cross the tracks would deter people from illegally and dangerously walking across the tracks.

It took 10 years to do so, but in 2016 the park district and Union Pacific Railroad hammered out a deal with details for six public access improvements at or on tracks between Martinez and Richmond — including the bridge at Pinole Shores and another one planned for Lone Tree Point to the north.

The new bridge is not cheap, though. The fifth-of-a-mile project — the 1,100-foot bridge and the adjacent 1,200 feet of trail — is costing $13.2 million, $6.1 million more than the $7.1 million engineering estimate made in 2016 before bids were put out, park officials say.

Added expenses were taken to protect the nearby marsh. Design changes were made to provide a larger buffer between the construction area and the railroad tracks, and protections for trees and a fuel pipeline in the narrow corridor.

Park officials say prices also went up because an upturn in the construction market is making it harder to attract lots of bids to hold down the cost of jobs.

In this case, the contract for the bridge and trail work — not including design and planning costs — attracted only one bid of $9.3 million from Gordon Ball, Inc. of Alamo.

To fund the project, the park district cobbled together money from nine sources, including $4.4 million in federal transportation funds, $2 million from Union Pacific and $1.4 million in state funds. Less than 30 percent of the funding came from park district bonds.

“We are leveraging our funds to help carry out this vision for a trail going all the way around the bay,” said David Mason, a park district spokesman.

Other remaining portions of the Bay Trail that will be difficult to plan include segments along Highway 37 in the North Bay, where officials are discussing how to elevate the entire low-lying shoreline highway to keep it above rising sea levels.

Huo, the planner for the Bay Trail project, said partnerships among local, region, state and federal agencies will be crucial to finishing the job.

“The Bay Trail is going to be a jewel,” he said, “but I don’t have a crystal ball to predict when the entire project will be finished.”