Rising Tides Expected to Take Toll on Transportation Infrastructure

One of the more significant impacts of climate change on the Bay Area’s built environment will be to transportation infrastructure. Many freeways, tunnels, bridge approaches, and transit corridors around the region are located near or even below current sea level and could be impaired during high tides and storm surges, to say nothing of the long-term implications of sustained sea level rise.

According to findings of the Adapting to Rising Tides (ART) project — a joint effort of the San Francisco Bay Conservation and Development Commission (BCDC) and the National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center — significant national, regional, and local transportation assets are at risk, even within the limited scope of the project’s target area, the Alameda County shoreline.

This extends to BART tracks, stations, and tunnels; street-level access to the Oakland International Airport; the Webster and Posey tubes linking Alameda Island to Oakland; passenger and cargo rail tracks; and sections of interstates 80 and 880.

Most of the ground-transportation assets evaluated by the ART project could be exposed to tidal or storm-event flooding by the end of century — and in some cases much sooner. Today’s occasional floods will be the future’s high tides.

But assessing risk and vulnerability is only the beginning. Planning for adaptation falls to subsequent reports, including two coming from ART later this year. These are preceded by a transportation-specific study released in December by the Metropolitan Transportation Commission (MTC), Caltrans, BART, and BCDC, and funded by the Federal Highway Administration, which also supported the transportation component of the initial ART assessment.

The recent study pushes science and policy efforts one step closer to action through a focus on three areas identified to be both highly vulnerable and poorly understood: the Oakland approach to the Bay Bridge, including the toll plaza and the Transbay Tube entrance; the Hayward approach to the San Mateo Bridge, including the toll plaza, the Bay Trail, and ecological assets; and the Oakland Coliseum area, including the new BART airport connector, the Coliseum BART station, the Amtrak station, and a section of Interstate 880. “We wanted to take a more significant, zoomed-in approach to vulnerability there, and then come up with some adaptation strategies,” said Lindy Lowe, a senior planner at BCDC and the project lead for ART. “We also wanted to see how the process works when you get to the project scale, as opposed to the regional scale.”

The latest document is as much a blueprint for future work as it is an advance in adaptation efforts for a few at-risk Alameda County locations. The three target areas benefit from the increased scrutiny and serve as case studies for the entire Bay Area. “We are doing the real work, while we’re also watching ourselves do the real work,” Lowe said. “There were a lot of processes that we developed that we think will be helpful moving forward, not only for these projects but for others around the region.”

For example, the agencies developed new criteria to weigh adaptation strategies, verified regional-scale flood maps against ground measurements, and agreed to more formally integrate climate-change considerations into decision-making processes — an outcome that alone could have far-reaching implications, Lowe said. “It was clear that transportation agencies need to have a more systemic approach to this problem than they have, and MTC and BART agreed too.”

Meanwhile, proposed adaptation strategies for the three targeted areas ran the gamut: at the Bay Bridge site, to build both a levee and an offshore breakwater at Radio Beach to protect the toll plaza from flooding and waves; at the San Mateo Bridge site, to conduct a drainage study to better understand existing conditions; and at the more inland Coliseum site, to build a levee around Damon Slough.

“It was quite surprising and alarming what happens at Damon Slough,” Lowe noted. “Flood control channels have to deal with not only the water that’s coming down, but also the new water that’s coming up.”

The City of Oakland plans to redevelop the Coliseum area, offering an opportunity to modify Damon Slough to better protect adjacent transportation assets, but other urbanized waterways throughout the region may not have it so easy, Lowe said. “There’s going to have to be a new water regime in those flood-control channels.”

The Alameda County waterfront isn’t the only place receiving such focused attention; similar adaptation efforts are underway in San Mateo County, Contra Costa County, Benicia, and San Francisco, while regional efforts include the Bay Area Climate and Energy Resilience Project and the nascent Regional Sea Level Rise Adaptation Strategy, both managed by the Joint Policy Committee, of which MTC and BCDC are members.

Nate Seltenrich (Nate-Reports.com) is a Petaluma-based science and environment writer.