Seattle Department of Transportation (subconsultant to COWI)
2018 - 2020
The 103-year old Ballard Bridge is a major connection across the Lake Washington Ship Canal. The bascule bridge opens for marine traffic, connects the Ballard and Interbay neighborhoods and is a key link to downtown Seattle. In 1982, it was added to the National Register of Historic Places.
While the bridge structure is currently in good condition, it is apparent that it will soon require significant rehabilitation. The Ballard Bridge Study looked at different options to not only improve the structure, but also to address functional and operational challenges. The study’s goal was to identify cost-effective solutions embraced by both the City and the community, so plans can be made for future improvements and for pursuing funding.
Working with teaming partners, SCJ’s design team first analyzed the existing corridor to determine constraints and opportunities. The neighborhood around the bridge is a highly developed corridor that constrains the footprint of a new design, as does the abutting Fishermen’s Terminal.
The existing bascule section of the bridge has a fixed, narrow sidewalk, requiring cyclists to eventually get off their bikes and walk across. The only other bike alternative across the Ship Canal is the Fremont Bridge, two miles away. This project also provides a way to address the needs of the bicycle and pedestrian communities.
Efforts had to be coordinated closely with Sound Transit to allow for the West Seattle Ballard Link Extension. A parallel bridge structure was not possible given the tight constraints. One possibility considered was designing a structure high enough to be built over the existing bridge, while another option was to build a temporary structure to the east that uses the same approaches. The team also coordinated with the Port of Seattle and BNSF regarding impacts to their facilities.
Evaluation of these constraints and opportunities allowed the design team to identify possible solutions, begin screening concepts, and package viable alternatives. These include a low-level rehabilitation of the existing bridge, a mid-level replacement that raises the structure approximately 30 feet and reduces the number of bridge openings, and a high-level replacement that eliminates all bridge openings. Each alternative improves bicycle and pedestrian connectivity across the bridge and replaces the Emerson/Nickerson intersection with a single point urban interchange (SPUI) designed by SCJ.
An alternatives analysis followed, comparing impacts on right-of-way, the environment, traffic operations, cost, constructability, and different modal connectivity. The goal of the analysis was not to select one alternative, but to identify the advantages and disadvantages of each option to help the City make informed decisions as they evaluate the entire corridor.
To help clearly communicate the options, SCJ’s Transportation Design team aided in the creation of graphics and boards for public display and represented the City at a series of public drop-in sessions.
For the Ballard Bridge, we tested out different innovative ideas to rehabilitate or replace this historic structure to see what would work best. I enjoyed starting the project from the beginning and working with every possible solution to try to find the best one for the City and community. In the end, we came up with three feasible bridge solutions for consideration that took into account vehicular, marine, and bike/pedestrian traffic. We also designed a cool single-point urban intersection (SPUI) design that would greatly improve traffic flow at the Emerson/Nickerson intersection.
Susann Babaei, PE