History of the National Bridge Inspection Program
On December 15, 1967, as holiday rush hour traffic streamed across the Silver Bridge between Ohio and West Virginia, it collapsed and sent 46 people tumbling to their deaths in the freezing Ohio River. This tragic loss of so many lives focused national attention on the condition of the nation’s bridges. In response to that tragedy, the Federal Highway Administration (FHWA) issued the National Bridge Inspection Standards (NBIS).
The NBIS, published April 27, 1971, established a program for regular comprehensive inspection of all federal highway system bridges. Minimum qualifications were set forth for bridge inspectors, specific types and frequencies for bridge inspection were established, and the reporting of certain standard information about each bridge was required. In 1978, these requirements were extended to all public bridges carrying vehicular traffic.
A national bridge inspection program has been in place ever since, and state and local agencies have performed bridge inspection in accordance with these guidelines.
City of Puyallup’s Bridge Inspection Program
The City of Puyallup has been inspecting all of it bridge assets, both road and trail, according to the requirements set forth by the FHWA and the NBIS. In the City’s Bridge Inventory files, there are historical inspection reports of the bridges dating back many years. Though the items reported have changed over time, these inspection reports can still give the reader a glimpse of the state of the City’s bridge structures. In 1995, the reporting method switched to one that would give a numerical number to better illustrate the overall condition, or health, of the bridge. This was called a Sufficiency Rating (SR) and it went from 100 (best) to 0 (worst/failure). This rating also allowed the system to indicate when a structure becomes Functionally Obsolete (FO) or Structurally Deficient (SD).
Functional Obsolescence (FO) occurs when a bridge does not meet current standards for such geometric parameters such as lane width, sidewalk width, guardrail, handrail, speed, clearance (over or under the structure), deck geometry, and alignment adequacy.
Structural Deficiency (SD) can occur when a bridge does not meet current operating load requirements; it has superstructure condition deficiencies, or sub-structure condition deficiencies.
The FO state is driven by the adequacy of the guardrail system, width of shoulders, sidewalk width, as well as the handrail system, and whether they meet current FHWA standards. The SD state is much more complicated. However, the primary driving forces are the rating of the superstructure and whether there is a load restriction on the bridge.
The City Bridge inventory consists of a total of 20 bridge structures. Of those 20, nine are traffic carrying structures that are required to be reported to WSDOT and FHWA. The remaining 11 structures are pedestrian bridges located in the City’s parks and trails.
The overall health of the City’s bridge system is rated at 78 out of 100, or a C+. The state and national average, according to the latest American Society of Civil Engineer report from 2013, rates State of Washington’s bridges as a C- and the nation’s bridges as a C+. Once the Milwaukee Bridge is rehabilitated in 2018, it is anticipated the City’s overall bridge grade would jump to a B- or a B.
Currently, the City has one bridge which is rated SD. This is the Milwaukee Bridge on 8th Ave NW. This project is currently funded to be rehabilitated using Federal Bridge Replacement Advisory Council (BRAC) funding. The City also has one structure listed as FO. This would be the bridge over Willows pond, located on 39th Ave SE.