During the environmental review phase, we will study and document the benefits and drawbacks of each alternative. By the end of this process, we will have selected a final alternative to design and build.
Over 100 options were studied during this project’s Feasibility Study Phase (2016-2018), including tunnels, ferries and other bridge options. From that study, four bridge alternatives (and a no-build or “do-nothing” option) were recommended for further evaluation.
The Fixed Bridge alternative was dismissed from further study in 2019 due to a large number of impacts that were identified through a navigational study. The Fixed Bridge would have extended far into town on both sides of the river to achieve the height needed for river traffic to pass underneath.
As part of the study, the In-Kind Replacement alternative expanded to include two design options, a conventional (Short Span) bridge alternative and a Long Span bridge alternative. The Long Span alternative is a variation of the conventional (Short Span) alternative that requires fewer support columns than the current bridge.
All the remaining alternatives are movable bridges and include:
Enhanced Seismic Retrofit
This alternative would upgrade the existing bridge to maintain functionality after a large earthquake and strengthen the bridge to accommodate heavy commercial vehicles, and to improve post-earthquake recovery. It includes a combination of retrofitting portions of the bridge and replacing others. The width would remain the same as the existing bridge.
Replacement: Short Span
This alternative would construct a new movable bridge at about the same height and location as the current bridge (also considered a conventional in-kind replacement). It would be wider than the existing bridge to accommodate more space for bikes, pedestrians and transit.
Replacement: Long Span
This alternative is a variation of the conventional (Short Span) replacement bridge that has longer and fewer spans, and thus requires fewer support columns. In order to build longer spans, additional above deck structure is needed. Like the Short Span alternative, the Long Span alternative would construct a new movable bridge at about the same height and location as the current bridge. It would be wider than the existing bridge to accommodate more space for bikes, pedestrians and transit.
Replacement: NE Couch Extension
This alternative would construct a new movable bridge of about the same height as the current bridge. The intent is to smooth out the tight existing NE Couch Street curve, allowing easier movement for freight, large vehicles, and a future westbound Streetcar. Instead of NE Couch Street connecting into Burnside where it does now on the eastside, the bridge would extend out and over Northeast 2nd Avenue and the highway and connect back to the bridge at a point over the river. At midspan, it would be wider than the existing bridge to accommodate more space for bikes, pedestrians and transit.
A cross section identifies how street space is shared among people walking, cycling, taking the bus and driving motor vehicles. The cross section for the Enhanced Seismic Retrofit alternative utilizes the existing bridge width, whereas the cross section for the Replacement alternatives provides additional width to accommodate all users.
Note: These cross sections do not include specific design features or amenities. Those details will be considered at a later point in the project.
Two options for travel during construction are being studied: 1) installing a temporary bridge to maintain some level of traffic during construction, and 2) fully closing the bridge and detouring traffic to other bridges.
Burnside Bridge construction is estimated to take approximately 4.5 to 5.5 years. A temporary bridge would increase that duration to approximately 5.5 to 6.5 years. The Environmental Review is studying the benefits and drawbacks of these options to help determine which is preferred.