North Spring Street Viaduct
In June 2011, the City Council ultimately supported a new innovative approach for the bridge, a design that balances preservation and engineering goals and reflects out-of-the-box thinking. The plan now calls for widening the bridge about half of the original plan (twenty-one feet instead of forty), and it would widen it on only one side, to the south. This approach meets all minimum traffic and safety standards and still allows for dedicated pedestrian and bicycle access.
We are confident that we now have a plan moving forward that should meet the Secretary of the Interior's Standards and retain eligibility of the bridge as an historic resource.
With much community input and participation, the design for the North Spring Street Viaduct may serve as a test case, and perhaps provide a path for moving forward on other bridge projects currently in the works.
The BOE first proposed to retrofit and widen the North Spring Street Viaduct in 2006; the plan called for widening the bridge by approximately forty feet (twenty on each side) to accommodate new eight-foot-wide sidewalks, five-foot-wide shoulders, and a center median with left-turn lanes at each end. As originally conceived in design and scope, this plan would likely have destroyed the North Spring Street Viaduct’s eligibility as a historic resource. The BOE’s primary justification for the project was to upgrade the bridge to meet “major highway standards” and to add pedestrian-bicycle lanes. No new traffic lanes will be added.
The plan lingered without any action until March 2010, but then underwent an accelerated environmental review process on an extraordinarily fast timeline, due in part to secure federal Highway Bridge Program funding that would otherwise be lost.
The BOE proceeded with the environmental impact report (EIR) at a rapid pace, much to the anger and frustration of people concerned about the bridge. The hastened project schedule also contributed to significant errors and omissions in the draft EIR. Adding insult to injury, the EIR failed to consider a single alternative that would maintain the bridge’s historic status.
Conservancy members and supporters came out in full force, responding to our action alerts with more than seventy letters to the City and speaking against the proposal at public hearings. A turning point came in December 2010, when the project was brought to the Mayor’s Design Advisory Panel for review. Panel members strongly supported the preservation of the North Spring Street Viaduct and criticized the widening proposal. The panel directed the BOE, bicycle advocates, and the preservation community to work together to develop a more creative approach that would not irreparably harm the bridge or jeopardize its eligibility as a historic resource.
In April 2011, the Bureau of Engineering (BOE) came back to the Mayor’s Design Advisory Panel and presented revised plans that further reduced the width of the proposed widening of the bridge. As proposed, two options were still under consideration: a reduced scale dual-side widening, and single-side widening to the south.
Fortunately, the BOE was very responsive to the concerns of the Conservancy and the broader community, as well as to guidance from the Mayor’s Design Advisory Panel and the office of City Councilmember Ed Reyes, whose district includes the bridge.
The plan now calls for a subtly differentiated design for the south side of the North Spring Street Viaduct. Instead of being replicated at a wider scale, the bridge would stay original on the north side and be widened on the south side with a new, yet compatible, design. The new design features a more modern, articulated double-arch span that complements the original north side.
The Conservancy has consistently stated two primary positions:
1) North Spring Street Bridge should retain its eligibility as a historic resource following any proposed work.
2) BOE traffic projections should be fully scrutinized to reflect accurate current and future traffic volume conditions, as well as the consideration of a road diet. Initially, the Conservancy advocated an alternative that would leave the historic bridge intact and construct a stand-alone pedestrian crossing alongside it—a strategy that has succeeded elsewhere across the country. The BOE ultimately rejected this option, partly because this type of approach would not qualify for available funding.
With the single-sided widening – the Conservancy’s preferred approach of the two options – the current four lane bridge would be widened by twenty-one feet on the south side only to accommodate five foot sidewalks, five foot bike lanes, and eleven feet wide travel lanes with a four foot wide center median.
While the scale of the widening was reduced greatly, the design treatment for the bridge was still very much an issue. Initially, the BOE presented a design that would replicate (or otherwise imitate) all the design features on the south side of the bridge.
The Conservancy opposed the initial “full replication” design based on our opinion that it would not meet the Secretary of the Interior’s Standards, national principles for preservation that are often used to help guide projects to make sure changes are done in a way that retains a structure’s eligibility as a historic resource.
While the Standards are somewhat subjective and they set forth no definitive approach for bridges, any alterations or modifications should generally be differentiated from the original so that they do not present a false sense of history. The design should also be implemented in a way that is reversible, so that it could be removed in the future without impairing the essential form and design of the original bridge.