The Federal government reports that there are 74,000 bridges in the US that are deficient. In light of the recent catastophic failure of the bridge in Minnesota, many people are asking more questions about what it means to have a deficient bridge. I tell people that it’s like being diagnosed with high blood pressure — you have to constantly monitor it, eat right, and if necessary take medicine — but it’s a managable health condition. The same holds true with our bridges. We have to inspect them, invest in them and take care of them. And because we do that, Kent bridges are safe, despite their deficiencies.
National Bridge Safety
Inspection of the nation’s bridges began after the 1967 collapse of the Silver Bridge at Point Pleasant, West Virginia. Undetected corrosion in the steel suspension led to a catastrophic structural failure of the bridge that claimed the lives of 46 people. In response, the United States Secretary of Transportation established National Bridge Inspection Standards (NBIS) with the passage of the Federal-Aid Highway Act in 1968.
The 1968 Act required each state to maintain a condition inventory of all Federal-Aid highway system bridges. This requirement was expanded in 1978 with the passage of the Surface Transportation Assistance Act to include inventory requirements on all local bridges on public roads greater than 20’ in length. The primary purpose of the NBIS is to locate, evaluate and act on bridge deficiencies to ensure the safety of the traveling public.
States generally requires bridge inspections to occur on an 18-24 month cycle, and Ohio falls in that category. Substandard bridges with advanced deterioration are often inspected on a more frequent basis, e.g., every six months.
Kent Bridge Inspections
The Engineering Division of the Department of Public Service serves as the lead agency in coordinating the City of Kent’s bridge inspection program with the Ohio Department of Transportation (ODOT). Because bridge inspections require a very specific expertise, Kent’s Engineering Division contracts with a state certified bridge engineering firm to perform the necessary inspection services.
The City shares bridge inspection responsibilities with the County and the State. For example, the City is responsible for all bridges on “city” streets, and the state is responsible for the bridges on any of the limited access highways in the City, e.g., Haymaker Parkway bridge. Likewise, the County still has responsibility for some bridges in Kent, e.g., Main Street bridge, as do the railroads due to some unique historical agreements, e.g., Middlebury Road used to be railroad maintained.
Here’s the bridges that the City is responsible for inspection and maintenance:
1. Sunrise (over Fish Creek)
2. Spaulding (over Fish Creek)
3. River Bend (over Cuyahoga River)
4. Mogadore Road (Plum Creek culvert)
5. Fred Fuller Park (over Cuyahoga River)
6. Cherry Street (Plum Creek)
7. Allen Drive (over Fish Creek)
8. Admore Drive (over Fish Creek)
9. Middlebury Road (over the Cuyahoga)
Here’s the County bridges:
1. Main Street Bridge (over the Cuyahoga & RR)
2. Crain Avenue Bridge (over the Cuyahoga)
3. Middlebury Road (over the railroad tracks)
Here’s the State bridges:
1. Haymaker Parkway (over the Cuyahoga and RR)
City bridge inspection includes a thorough on-site review of the structural elements of the bridge. Detailed records and photographs are used to identify problem areas and to monitor changes in bridge condition over time. This data is summarized on a “Bridge Inventory and Bridge Inspection Sheet” that is completed by the inspection team for each bridge.
The Bridge Inventory and Inspection Sheets are completed in the field and then the engineers use the field data to derive a numeric bridge “sufficiency” rating for each bridge (0=closed to 9=as new, excellent). The use of this scoring methodology provides a quantitative indication of relative bridge condition and public safety risk.
Here’s a general overview of the inspection and rating process:
ODOT has minimum bridge standards and if bridge ratings fall below those safety standards the bridge may be classified as either structurally deficient and/or functionally obsolete. A structurally deficient bridge typically has significant problems (deterioration, corrosion, strength loss, etc.) in the load bearing parts of the bridge. A functionally obsolete bridge would be an older bridge that was constructed using a design that fails to meet current design standards, e.g., bridge rails substandard, lanes too narrow, vertical and horizontal alignment substandard, etc.
Public safety is the main objective of bridge inspections and because structural deficiencies represent a greater risk to public safety than functional obsolescence, the structural deficiencies tend to carry more weight than the functional elements in the sufficiency formula.
Kent Bridge Ratings
So what does all this data mean?
It means Kent’s bridges, like bridges all over the US are aging, and need routine attention — which they get thanks to the inspections. And for those bridges that are showing their age the most, the City has capital projects programmed to take care of them.
As the folks in Minneapolis discovered, there are no guarantees, even with relatively new bridges, but the City will always err on the side of caution to be sure Kent’s bridges remain safe.