International Bridge Technologies

Sound Transit East Link Extension I-90 Crossing – Seattle, Washington

Technical details
Sound Transit Central Puget Sound Regional Transit Authority

Construction Completed: 2023

Seattle, Washington
Prime Consultant: HNTB, Jacobs, Hatch, and Mott MacDonald
Contractor: Shimmick and Parsons
SYSTRA IBT’s Role: Segmental Superstructure Design Consultant


Main Span: 360 ft (109.8 m) main span, 245 ft (74.7 m) and 250 ft (76.2 m) side spans.

The Sound Transit East Link Extension I-90 Crossing expands the existing Seattle light rail system from Seattle across Lake Washington to Bellevue.

The 14 mi (22.5 km) alignment is primarily situated at grade with isolated elevated and tunnel sections. The I-90 crossing at the eastern terminus of the I-90 floating bridge is one of two long-span structures along the alignment. This cast-in-place segmental balanced cantilever bridge includes a 360 ft (109.8 m) main span with 245 ft (74.7 m) and 250 ft (76.2 m) side spans.

The double-track alignment traverses a compound curve with a minimum centerline radius of 526 ft (160.4 m). The segmental super-structure consists of 175 ft 8 in (53.6 m) cantilevers off of each of the two main piers and 60 ft 6 in (18.4 m) and 65 ft 6 in (20.0 m) falsework sections at each end pier. Typical segments are 15 ft 4 in (4.67 m) long.

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