+47.64754, -122.34736
47°38'51" N, 122°20'50" W
Source: National Bridge Inventory
Information not verified. Use at your own risk.


Name:SR 99 over LAKE UNION
Structure number:0001447A0000000
Location:7.7 N JCT SR 509
Purpose:Carries highway and pedestrian walkway over highway, waterway, and railroad
Route classification:Principal Arterial - Other Freeways or Expressways (Urban) [12]
Length of largest span:799.9 ft. [243.8 m]
Total length:2955.2 ft. [900.7 m]
Roadway width between curbs:56.4 ft. [17.2 m]
Deck width edge-to-edge:69.6 ft. [21.2 m]
Vertical clearance below bridge:134.8 ft. [41.1 m]
Owner:State Highway Agency [01]
Year built:1931
Historic significance:Bridge is on the National Register of Historic Places [1]
Design load:M 18 / H 20 [4]
Number of main spans:8
Main spans material:Steel [3]
Main spans design:Truss - Deck [09]
Deck type:Concrete Cast-in-Place [1]
Wearing surface:Bituminous [6]

Latest Available Inspection: August 2015 

Status:Open, no restriction [A]
Average daily traffic:58,319 [as of 2012]
Truck traffic:3% of total traffic
Deck condition:Satisfactory [6 out of 9]
Superstructure condition:Fair [5 out of 9]
Substructure condition:Satisfactory [6 out of 9]
Structural appraisal:Somewhat better than minimum adequacy to tolerate being left in place as is [5]
Deck geometry appraisal:Basically intolerable requiring high priority of replacement [2]
Underclearances appraisal:Somewhat better than minimum adequacy to tolerate being left in place as is [5]
Water adequacy appraisal:Equal to present desirable criteria [8]
Roadway alignment appraisal:Equal to present desirable criteria [8]
Channel protection:Banks are protected or well vegetated. River control devices such as spur dikes and embankment protection are not required or are in a stable condition. [8]
Pier/abutment protection:Navigation protection not required [1]
Scour condition:Bridge foundations determined to be stable for the assessed or calculated scour condition. [8]
Operating rating:40.6 tons [36.9 metric tons]
Inventory rating:23.8 tons [21.6 metric tons]
Evaluation:Functionally obsolete [2]
Sufficiency rating:46.5

Previous Inspections 

DateSuff. ratingEvaluationDeckSuper.Sub.ADT
August 201546.5Functionally obsoleteSatisfactoryFairSatisfactory58319
August 201346.5Functionally obsoleteSatisfactoryFairSatisfactory58319
August 201144.4Functionally obsoleteSatisfactoryFairSatisfactory69463
December 200944.1Functionally obsoleteSatisfactorySatisfactoryFair71085
June 200755.2Functionally obsoleteSatisfactorySatisfactorySatisfactory73836
May 200553.2Functionally obsoleteSatisfactorySatisfactorySatisfactory73836
July 200353.2Functionally obsoleteSatisfactorySatisfactorySatisfactory73836
March 200153.2Functionally obsoleteSatisfactorySatisfactorySatisfactory73836
June 199953.2Functionally obsoleteSatisfactorySatisfactorySatisfactory73836
May 199759.3Functionally obsoleteSatisfactorySatisfactorySatisfactory73836
May 199527.9Structurally deficientSatisfactoryPoorSatisfactory73836
June 199329.3Structurally deficientSatisfactoryPoorSatisfactory59363
January 199227.8Structurally deficientFairPoorSatisfactory59363