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Transportation Final 10-15-11 -   2.2 - State Bridge Conditions

 
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Transportation Final 10-15-11
1. Safety
2. Preservation
3. Mobility
4. Ferries
5. Stewardship
Action Plan
  
 
 

2.2 - State Bridge Conditions
What percentage of WSDOT-owned bridges are in fair or better condition?

 
 
Data Notes
Data Source:

WSDOT Bridge and Structures Office.

Measure Definition:

Data as of June, 30, 2011. Good -A range from no problems to some minor deterioration of structural elements; Fair-All primary structural elements are sound but may have deficiencies such as minor section loss, deterioration, cracking, spalling, or scour. Poor -Advanced deficiencies such as section loss, deterioration, cracking, spalling, scour, or seriously affected primary structural components. Bridges rated in poor condition may have posted truck weight restrictions.

Target Rationale:
Link to Agency Strategic Plan: Objective 2.3: Preserve and replace state bridges to provide safety and operability.
Relevance: The goal is to maintain 97% of all bridges in good or fair condition.

Notes: (optional)

 

Condition rating is based on the structural sufficiency standards established in the FHWA Recording and Coding Guide for the Structural Inventory and Appraisal of the Nation’s Bridges, which relates to the evaluation of bridge superstructure, deck, substructure, structural adequacy, and waterway adequacy.

* For fiscal year 2011 NBIS deck codes are now included as part of the "good/fair/poor" performance measure, previously only superstructure and substructure codes were included. The addition of deck codes brings WSDOT’s "good/fair/poor" into alignment with FHWA’s SD metric.

Also Available

Action Plan: Yes
Extended Analysis: Yes

 Drill Down Measures

 Summary Analysis

As of FY 2011 95% of WSDOT Managed Bridges in Good or Fair Condition

Inventory and Conditon Ratings

  • WSDOT manages over 3,039 vehicular bridge structures over 20 feet in length, 95% of which are currently in fair or better condition. The majority are in good condition (86%), while 9% are in the fair category. 
  • Roughly 5% of bridge structures (4.8%) had a condition rating of poor. No bridge that is open to traffic and rated as “poor” is unsafe for public travel.

WSDOT's "Good/Fair/Poor" Performance Measure

  • WSDOT's performance measure classifies bridges as good, fair, or poor using the National Bridge Inspection Standards (NBIS) bridge superstructure, substructure, and deck codes. Previously, WSDOT only used superstructure and substructure codes. For fiscal year (FY) 2011, the deck code was included as part of the performance measure because WSDOT has made improvements in the measurement and consistency of this data and the bridge deck is a primary load-carrying element. Prior to FY 2011, deck area codes were excluded due to data quality issues, which WSDOT has since worked to improve through better tracking.
  • The criteria WSDOT uses to determine the number of bridges in “Good/Fair/Poor” condition now matches the criteria used by the Federal Highway Administration (FHWA) to classify bridges as structurally deficient (SD), the number of WSDOT bridges rated “poor’ is now equal to the number classified as SD.

Inspections

  • All bridges in the state are inspected every two years using national standards.
    • There are exceptions: some bridges require annual (or quarterly) inspections due to their condition or design, while FHWA approved WSDOT to inspect newer concrete bridges that are in good condition every four years. 
    • For 2011, WSDOT has scheduled 1,500 bridges for inspection. Under-bridge inspection trucks (UBIT) will be required on 234 of those inspections.

Maintenance and Preservation

  • WSDOT prioritizes bridge preservation and replacement based on risk, condition, location and use, to make investments that extend the service life or, when necessary, replace the bridge. Bridges on key state and freight routes receive higher priority.