GovernmentSeattle, WA2024
Cascade Crossing
Challenge
A 1.2-mile elevated transit corridor spanning a major interstate highway and active railway, requiring seismic resilience for a 2,500-year return period and minimal traffic disruption during construction.
Approach
We used accelerated bridge construction with prefabricated segmental concrete box girders launched from both ends simultaneously. A real-time GPS monitoring network tracked alignment to within 3mm tolerance across all spans.
Result
The corridor opened four months early, carried its design-load certification on first attempt, and received the ENR Best Projects award for transportation.
Project details
- Length
- 1.2 miles
- Spans
- 14
- Max Span
- 280 ft
- Timeline
- 36 months
Client
Washington State DOT