The Earthquake Ready Burnside Bridge project is moving forward, despite an unresolved funding strategy. As Multnomah County works through the formal environmental impact process, public outreach is already shifting focus to the new bridge design. This post records the public comments that I submitted for both concurrent phases of outreach.
Draft Environmental Impact Statement
There are a few sections of the DEIS that appear biased against retaining the bridge. For example, the historic section 104f analysis places unwarranted importance on the Burnside skatepark relative to the bridge. The impact of losing the national register listed bridge is orders of magnitude more significant than the impact of losing the register-eligible skatepark. Saving the skatepark barely makes a dent in mitigating the impact of losing the bridge.
The analysis also appears to neglect the shorter construction time for the retrofit alternative. The seismic analysis report proposes phased construction that would enable temporary bridge access during construction. But other sections of the DEIS state that the retrofit requires a full 3.5 year closure. Table 2.2-2 states a 2 year closure for bridge access within the 3.5 year construction timeframe, compared to a 4 year closure with the long span alternative. Regardless of the specific duration, the retrofit alternative appears to deliver the project sooner and with shorter construction impacts than all replacement alternatives.
The project team concludes that it is not possible to seismically retrofit the Burnside Bridge while maintaining its historic integrity and designation. They also propose a significantly different form to replace the historic bridge. The Burnside Bridge is among the largest and most prominent historic resources in Portland. The team should take every practical measure to save as much of the history as possible. The massing and form of the historic bridge should be preserved even if the physical structure must be replaced. Therefore, a short-span replacement is more appropriate than a long-span bridge if the existing bridge cannot be saved.
Bridge Type Selection
West (Shorter) Span
A girder approach for the west span is the most respectful of the current historic bridge profile. It improves the openness below the bridge with the removal of dozens of existing columns while maintaining the completely open above-bridge experience. This above-bridge transparency preserves views into and from the historic buildings at the west bridgehead. Using the girder approach for the new bridge sets a strong precedent for appropriately-scaled (contextual) new construction within the adjacent historic districts. And girders best reflect the historic condition exhibited by the current bridge.
Center (Operable) Span
The center span should remain a bascule configuration similar to the existing bridge. The current bascule span is mirrored in the adjacent Morrison bridge. Together these two slender-profile bascules are bookended by bulky through-truss vertical lift bridges that define the waterfront extents of downtown. Introducing vertical lift towers on the Burnside bridge would clutter this implied logic and symmetry in the four-bridge configuration along the downtown core waterfront. Additionally, the bascule lift minimizes above-deck structure to preserve views from the bridge to the city and across the bridge from adjacent buildings.
East (Long) Span
A through-truss structure reinforces the industrial character of existing downtown bridges, directly referencing the Hawthorne, Steel, and Broadway Bridges. A through truss also references the existing below-deck trusses on the Burnside Bridge, but in a likely-more-cumbersome way. The existing trusses visually disappear below the deck’s shadowline, allowing the decorative guardrail to read as the most prominent design feature along the length of the bridge. The existing bridge stands out for its elegant design, from the thin profile to the decorative operator’s houses and the arched concrete railings. The tied arch concept best reflects the restrained elegance of the original design, particularly if thoughtfully detailed and paired with the west girder and bascule options.
However, the design team should reconsider a shorter-span girder strategy for the east approach. The repeated public statements that this is not feasible attempt to preemptively avoid such suggestions while showing that the community has already pushed for this approach. It is of course feasible to add one or more additional support piers, with corresponding geotechnical improvements, to reduce or eliminate the above-deck structure on the east side. While this may ultimately result in a design closer to the “short-span” alternative that was previously considered, minimizing the overall scale of the new bridge structure is necessary mitigation for the removal of the historic bridge.
Bridge Type Summary
The new bridge should be respectful of the historical condition. The current bridge is low-profile, creating expansive views from and over the bridge. The Burnside Bridge acts as a visual couple with the Morrison Bridge, symmetrically bookended by visually-heavy through-truss vertical lift bridges.
All of the proposed east span structures are overscaled relative to building height limits (and built projects) at the eastside bridgehead. There is presently an implied gateway configuration with two 200-foot-tall towers at either side of the east bridgehead. Introducing an even larger vertical bridge element adds complexity to the overall skyline composition. The large bridge structure on the east span draws attention to this side as the asymmetrically-longest span. Given that most of the span is not over water, the result visually promotes the existing freeways as the most important element below the bridge along its length. The design should instead seek to draw focus to the river, and to waterfront park. Ideally the design of this new 100-year bridge will promote the eventual decommissioning of the eastside waterfront freeways.
If the new bridge introduces a more substantial “iconic” element, it should focus on a single feature. Multiple towers or arches spread across different spans are not coherent. Any combination of cable-supported and lift bridges should seek to consolidate the towers supporting each span. The current bridge uses the two bascule piers and associated control towers as the primary iconic feature. These elements are elegant in their restrained proportion and are appropriately scaled to the historic structures at either end of the bridge.
Conclusion
The design team should consider how the bridge relates to all existing elements of the built environment. This includes the historic buildings at both bridgeheads, as well as the newer buildings on the east side, and the adjacent Willamette River bridges at a larger contextual scale. The Burnside Bridge represents both a critical functional link between high-density nodes and iconic wayfinding element as the central east/west axis for Portland. The design should better respond to these considerations than the existing bridge to support the approach to demolishing the historic bridge, even if the resulting design carries a larger cost.