Caltrain issues emergency order to repair rail bridge that connects Menlo Park, Palo Alto

Caltrain declared an emergency on Monday, March 27, to repair damage to the embankment that holds up the rail bridge between Palo Alto and Menlo Park after a series of recent storms undermined the soil supporting the structure.

The Caltrain Finance Committee voted to authorize the emergency, which allows the rail agency to enter into a construction agreement to repair damage to the north embankment of San Francisquito Bridge.

Caltrain personnel examined the bridge after the recent storms and found that on the Palo Alto side (the southern side), the concrete wall that protects the bridge abutment and the historic El Palo Alto redwood had moderate scouring below the base of the concrete wall. Scouring is the localized loss of soil around the foundation.

The bridge is directly adjacent to El Palo Alto Park and the iconic El Palo Alto redwood, the city’s namesake. The storm drain below the park, the embankment and the concrete bag slope protection for the drain’s outfall pipe also experienced severe scour and embankment erosion. The loss of supporting soil is also compromising the structural integrity of the outfall, said Rob Bernard, deputy chief of design and construction.

The pedestrian footbridge that is just east of the rail bridge also is in a similar condition with erosion to the embankment below and needs stabilization, he said.

On the north side is the Menlo Park section, where the bridge was far more threatened. That side of the structure is held up by the dirt embankment rather than concrete, Bernard said during Monday’s meeting. Underneath the railroad bridge, the soil embankment experienced severe scour that has undermined the bridge’s eastern span. A large tree nearby also now has an exposed root mat from significant soil erosion and scour around that tree. The bank soil, which is now nearly vertical rather than at a slope, is unstable. Consequently, the soil will continue to erode if action is not taken, Bernard said.

“Now I want to be very clear … the bridge is not in imminent danger. However, an emergency repair is necessary to prevent additional erosion, which could undermine the structure. So it’s not an imminent danger, but we must act (now),” he said.

Caltrain is proposing to restore or backfill the slope with soil on the Menlo Park side near the railroad bridge to the proper angle for stabilization, and then would provide protection against further erosion and scour. One proposed option would build a concrete wall on the Menlo Park side similar to the existing one in Palo Alto, but that design could be potentially damaging to the Central California Coast steelhead, a federally protected endangered fish species living in San Francisquito Creek, Bernard said. A less invasive method would add “riprap,” which are large boulders to protect the repaired bank, he said.

Any work would need to be finished within a narrow window of about four months, from June 1 through Oct. 15, when it would not interfere with the fish migration, Bernard said. Caltrain would need to prepare its plans and have them and the permitting approved in the next two months, he added. Eight agencies would review the design.

Caltrain doesn’t yet know what the project will cost, however. Staff expects to come back with estimates in about a month, Bernard said.

The emergency declaration allows Caltrain to speed up the process by bypassing the usual bidding process and awarding the contract to Walsh Construction, which is currently working on repairs at another bridge in south Santa Clara County, he said.

Caltrain board member Ray Mueller, a San Mateo County supervisor who was a Menlo Park City Council member for 10 years, said he wants to make sure that all of the stakeholders are included in the process and that Caltrain gets a release from liability for the work.

“There are, I can tell you, further down that bend (of the creek), there are homes that are being affected by pretty significant erosion taking place. And I am a little concerned and I’m sure our engineers will work it out. But if you replace that with concrete, will that actually speed up the water flow going through that area?” he said.

Dan Lieberman, a spokesperson for Caltrain, said the agency is aware of the historic El Palo Alto tree and the work will not cause any impacts to it.

“The emergency repair work will focus on the north channel embankment while the El Palo Alto tree is located on the south side of the creek,” he said.

Palo Alto City Council member Pat Burt, who is on the Caltrain board, said by phone on Thursday that he wants to make sure that Caltrain’s work doesn’t damage El Palo Alto.

“I want to make sure there’s a hydrologist involved and … that there’s not a shift in scouring to the south side,” he said.

The Palo Alto council’s Rail Committee also discussed the situation at its meeting on Wednesday, March 29, he said. He acknowledged that Caltrain is under a serious time crunch to repair the damage before it gets worse.

“There’s a real sense of immediacy before the next rainy season,” he said.