Mercer County Engineer's Office
About Us
Current Conditions
Links To The Past
Future Projects
History
Inspection
Design Process
Historic Bridges
CURRENT CONDITION OF OUR BRIDGES
AS OF JANUARY 1, 2012
AS OF JANUARY 1, 2012
Mercer County owns and maintains 255 bridges throughout the county. Of these, two are owned jointly with Trumbull County, Ohio, three are owned jointly with Crawford County, Pennsylvania, and one is owned jointly with Coolspring Township. The physical cost to replace all county owned bridges using base year 2002 costs amounts to $100,021,000. This figure represents the base construction cost and does not include design, inspection, right-of-way, and utility costs which are typically required to replace a structure.
Mercer County has 76 bridges, or roughly 30% that are considered "Structurally Deficient" or "Functionally Obsolete". In Pennsylvania, 34% of the bridges on the State system and 46% of the bridges on the local system are considered structurally deficient or functionally obsolete according to figures released for the year 2010 by the Better Roads magazine bridge inventory. Our bridges are in overall better condition when compared to both the state and local averages. Mercer County has removed six bridges from the Structurally deficient/Functionally obsolete category in the last year. However, four new bridges have been added to the structurally deficient list due to coding revisions for non-composite adjacent box beam bridges.
A bridge is Structurally Deficient if it is in relatively poor condition, or has insufficient load-carrying capacity. The insufficient load capacity could be due to the original design of an older bridge that used lighter design loads, or due to deterioration. A bridge is considered Functionally Obsolete if it is narrow, has inadequate under-clearances, has insufficient load-carrying capacity, is poorly aligned with the roadway, and can no longer adequately service today's traffic.
Federal law requires that all bridges on public roads be inspected at least once every two years in accordance with the National Bridge Inspection Standards (NBIS). Due to the large number of bridges in Mercer County, we inspect half one year and the other half the following year. Our inspection report data is sent to PennDOT for entry into their computer system and reporting to the federal government. Approximately 900 items are inventoried, reviewed and catalogued at each inspection for each bridge.
All bridges in Pennsylvania are inspected using the same criteria, and numeric ratings are assigned to various parts of the structure. All inspectors, if they are not registered engineers, are required to attend inspection training to assure all inspection conditions are properly coded and recorded. These numeric codes are used to develop what is known as the structure's federal sufficiency rating which indicates the overall condition of the structure and how critical it is in relation to other structures throughout the country.
The Pennsylvania Department of Transportation uses the numeric ratings to also determine a "Deficiency" rating. The deficiency rating system assigns higher priorities to bridges on the Interstate and Arterial roads than to those on collector or local roads. Based on the deficiency ratings computed, bridges are ranked County wide, District wide, and State wide.
Mercer County's worst bridges have federal and/or state funds allocated for either design or design and construction on the State Transportation Improvement Program. The federal or state participation is at least 80% of the cost with the remaining cost to be borne by the County. Therefore, our worst bridges are on a schedule to be addressed.
The state of Mercer County's bridges has been gradually improving due to an aggressive maintenance and replacement program. In 1983, the average sufficiency rating for all Mercer County owned bridges was 74.39 on a scale of zero to 100, with 100 representing a new structure. In 2004 this had increased to 86.94, and today it has fallen to 80.88. Although we have removed bridges from the Structurally deficient/Functionally obsolete category, the continued deterioration of the remaining bridges is expected to reduce the average rating over the next few years. We should not expect this number to go much higher. Approximately 46% of our bridges are between 40 and 144 years old, and the sufficiency ratings decrease more rapidly as a structure ages.