If you walked or biked the Iron Horse Trail toward Danville this week, you probably hit orange fencing near the Glen Arms Drive and Laurel Road access point. Caltrans is working on the I-680 overpass that crosses above the trail there, in the stretch between Sycamore Valley Road and San Ramon Valley Boulevard, and the notice on the East Bay Regional Park District's own trail page was updated August 2, two days before this was written. Riders are being told to stay on the paved path and use caution passing through.
It is a minor closure as these things go. But it is also the latest entry in a pattern that anyone who uses this trail regularly has probably noticed without naming it: a flat, paved, decades-old rail-trail that keeps getting torn up, re-engineered, and rebuilt, section by section, as if it were still under construction rather than finished infrastructure. It is not your imagination. The trail actually is still being built, in a legal sense, and the reason traces back to a deadline the state of California set in 1989 and then quietly let slide.
The Land Was Never Fully Released
The corridor started as a Southern Pacific Railroad line, first run in 1891, negotiated in part by August Hemme of Alamo and Grange members from across the county. The East Bay Regional Park District, which now manages the trail, says the line was abandoned in 1978 after decades of hauling hay, grain, and fruit through the valley. Contra Costa County then spent 1983 to 1989 acquiring the right-of-way, using money that was never meant for a recreation trail at all.
That money came with strings. Three grants from the California Transportation Commission required the county to identify, by June 30, 1989, a specific plan for a busway or an exclusive mass-transit guideway along the corridor. District 2 Supervisor Candace Andersen has described what happened next in recent presentations to the Danville and San Ramon city councils: the deadline passed, the state chose not to collect on what she estimated would be roughly $10 million in present-day dollars, but it never released the county from the underlying obligation. Contra Costa was still required to preserve the corridor for some future form of mass transit, indefinitely, with no new deadline attached.
That is the clause. It is why the trail you walk your dog on is not, legally, just a trail.
"I've had very informal discussions with people in Alameda County," Andersen said of extending the concept toward Dublin. "Wouldn't it be great through Dublin, and we could also get them to do a bifurcated trail."
Why San Ramon's New Bridge Is Only for Bikes and Feet
The mass-transit reservation came with a specific engineering requirement: a 34-foot vertical clearance had to be preserved along the corridor in case a future transit line needed it. That requirement is the direct reason the Iron Horse Trail Bicycle and Pedestrian Overcrossing at Bollinger Canyon Road took the shape it did when it opened to the public on July 19, 2025. Once the county was able to lift that clearance mandate for this segment, San Ramon was cleared to build a bridge sized for cyclists and pedestrians instead of holding the space open for a train or busway that has never materialized.
According to the city of San Ramon's own project summary, the $29 million bridge is a 340-foot cable-stayed span anchored by 900 feet of approach walls, and more than 82 percent of the funding came from outside sources: the Bay Area Air Quality Management District, MTC's Transportation for Livable Communities Program and One Bay Area, the Tri-Valley Transportation Commission, and Contra Costa Transportation Authority Measure J funds. Local property owners were not asked to cover the bulk of this.
The project has since been recognized well beyond San Ramon. In late February 2026, it received the Outstanding Local Streets and Roads Project Award from the California State Association of Counties, the League of California Cities, and the County Engineers Association of California, an honor given to only one project statewide each year. On March 5, 2026, it picked up two more from the American Public Works Association:
- The 2026 APWA Project of the Year for a transportation project between $25 million and $75 million
- The 2026 Northern California APWA Project of the Year, chosen out of 25 nominated projects, the highest-level honor the chapter gives
That second award automatically qualified the bridge for the APWA National Competition, which runs at the Public Works Expo in Houston, Texas, later this month.
The Next Decision Splits Toward San Ramon or Danville
The county is not done. A design phase is currently underway for an express bicycle lane along the trail, and Andersen has said the pilot project is planned for the stretch between San Ramon's current overcrossing at Bollinger Canyon Road and the future one planned at Crow Canyon Road, which puts the first real test of this idea squarely inside San Ramon rather than a neighboring city. She has also started design on the first phase of a related "dual tracking" project, meant to physically separate wheeled traffic from pedestrians, which she put at roughly 65 percent complete as of the July 2026 update, funded in part by about $500,000 in park impact fees collected from unincorporated San Ramon.
Once San Ramon's segment is built and tested, the county has already named where it looks next.
| Segment | City | Status as of July 2026 | What's driving it |
|---|---|---|---|
| Bollinger Canyon Rd. to Crow Canyon Rd. overcrossing | San Ramon | Design phase, dual-tracking ~65% complete | First pilot for the express bike lane concept |
| Crow Canyon Rd. to Sycamore Valley Rd. | Danville | Top candidate for the next phase | Named by Andersen as the leading option after San Ramon |
| Segment near Dublin/Pleasanton BART | Dublin (Alameda County) | Informal discussions only | Tied to a new pedestrian bridge already built in downtown Dublin |
Andersen has also talked about the road not taken. Before the current bike-lane pilot took shape, the county studied a very different use for this reserved right-of-way. In a 2020 study on what officials called a "bicycle super-highway," the county looked at Glydways, then still operating under the name Wayfair, an autonomous pod system built to travel in a lane roughly the width of a bike path. Andersen has confirmed the concept is not being pursued now, but it is a useful reminder of how open-ended that 1989 mass-transit clause really is. Almost anything that moves people through a narrow, grade-separated corridor has qualified as a candidate at some point.
What This Means If You Use the Trail Every Week
None of this changes what the trail is for most people on a normal Tuesday. The city of San Ramon's own page on the Iron Horse Trail still describes 4.24 miles through the city, flat, paved, wheelchair accessible, open to walkers, runners, cyclists, equestrians, and leashed dogs, with views toward the Mt. Diablo ridgeline along the way. That has not changed and is not on the table to change.
What has changed is the assumption that the trail is a finished piece of infrastructure that will look the same next year as it did last year. It will not. Between the active Danville-area detour, the design work already underway inside San Ramon, and a named list of segments the county is eyeing next, this corridor is going to keep showing up in city council agendas for a while. If you rely on a specific stretch for a daily walk or a commute ride, it is worth checking the city's construction pages before you plan around it, rather than assuming the version of the trail you know today is the final one. If dog-friendly options along the way are more your focus, we have gone deeper on that in a separate guide to San Ramon's parks, trails, and play spaces.
The trail earned three of California's top public works awards this year for a reason. It is also, underneath the new plantings and the bridge deck, still the same piece of land the state set aside for a train that was never built. San Ramon is currently the city deciding what comes next.
If you are watching how a place like San Ramon keeps investing in the infrastructure around it and wondering what that means for property values or timing a move here, that is exactly the kind of on-the-ground read Cynthia Money tracks for clients across the East Bay. Reach out to request your personalized consultation.
