Washington State Department of Transportation’s State Route 520 Montlake Lid and Bridges project improved safety in an earthquake-prone area. State Route 520 is a vital connection across Seattle’s Union Bay, linking the Montlake neighborhood to the SR 520 floating bridge and Eastside communities. Built in the 1960s, the original structure relied on hollow columns and sat near three fault lines, making it vulnerable to collapse during a major earthquake—posing significant risks to public safety and regional mobility. To address these challenges, the Washington State Department of Transportation delivered the $487 million State Route 520 Montlake Lid and Bridges project, significantly improving both motorized and nonmotorized travel. The project replaced the vulnerable structure with a new earthquake resilient bridge and added a three-acre landscaped lid featuring regional transit stops and public open space. New bicycle and pedestrian trails now connects local and regional networks, including a car-free bridge over the highway. Located at one of the state’s most complex interchanges, the project also improved traffic flow through new high occupancy vehicle or HOV lanes, Americans with Disabilities Act accessible transit stops, and a multimodal transit hub with bike lockers and dedicated bus access ramps.