I-90 over Mercer Slough

Poor Condition86 years old74,410 vehicles/day

Location

StateWashington
CountyKing
Location6.4 E Jct I-5
CarriesI-90
CrossesMercer Slough
Coordinates47.57953, -122.19022

Condition Ratings

Overall ConditionPoor
Deck6 (Satisfactory)
Superstructure4 (Poor)
Substructure6 (Satisfactory)
Channel/Waterway8 (Very Good)
Scour Critical4 — Foundations need monitoring

Physical Characteristics

MaterialConcrete Continuous
DesignBox Beam - Multiple
Total Length2812.0 ft (857.1 m)
Max Span95.1 ft (29 m)
Deck Width65.0 ft (19.8 m)
Deck Area16970.6 sq m
Main Spans7
Year Built1940 (reconstructed 1970)

Traffic

Avg Daily Traffic74,410 (2023)
Truck Traffic3%
Lanes On Bridge4
Lanes Under Bridge4

Inspection & Ownership

Last Inspection223
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Structure Number0008610B0000000

Nearby Bridges

I-90 over Mercer Sl 0.0 mi Poor I-90 S-e Ramp over I-90 Mercer Slough 0.1 mi Fair E-e Ramp over I-90 Ramps Mercer Sl 0.1 mi Good I-90 over Mercer Slough 0.2 mi Fair I-90 over Mercer Slough 0.2 mi Fair I-90 over Mercer Slough 0.2 mi Fair I-90 W-n Ramp over I-90 Wbcd 0.3 mi Fair Skagit Key over Coal Creek 0.5 mi Good Newport Key over Coal Creek 0.5 mi Good I-90 Ramp over Mercer Slough I-90 0.5 mi Good