Bridge Inventory Management and Maintenance Program

Orange County Public Works (OCPW) maintains 64 bridges within unincorporated Orange County. OCPW has developed a Bridge Inventory Management and Maintenance Program (BIMMP) to organize and monitor bridge inventory, rank bridges by type of work needed, and identify bridge projects for County’s Capital Improvement Plan (CIP) and Maintenance Improvement Plan (MIP). Currently County’s MIP averages $2.5M dollars a year and consists of maintenance of 3-4 bridges per year and County’s 7-Year CIP includes 9 bridges identified for replacement and rehabilitation, valued at approximately $74M.
BIMMP organizes inspection data from Caltrans bi-annual bridge inspection reports for bridges registered in the National Bridge Inventory (NBI) database. Caltrans inspection reports include conditions and rankings of various elements of the bridges and work recommendations. County supplements Caltrans inspection reports with its own inspections to verify work recommendations. For structures that are not inspected by Caltrans but are still within County’s jurisdiction, OCPW performs own inspections to collect data of the bridge components. The County combines its own inspection data with that of Caltrans to get a comprehensive understanding of the maintenance needs.
Once the condition data is entered into the database, bridges receive a ranking based on a pair of scores that determine their relative priority compared to other bridges in the County’s inventory. First, a bridge receives a score based on an importance factor as determined by (1) the current average daily traffic, (2) the condition score of the bridge, and (3) a special bridge ranking modifier that is used to adjust for site-specific conditions such as proximity to critical infrastructure, lack of detours, etc. The second component of the ranking score is determined by the work recommendations associated with the bridge. These important factors are compiled in three different ways to create a score for the bridge where larger work recommendations and higher importance work will increase the bridge ranking. The first method ranks the bridges by the single most important work item for each bridge. The second method ranks the bridges by the sum for the work item scores. Finally, the third method takes the vector sum of the prior two methods and gives a clear picture of priority candidates for maintenance or capital improvement projects.
The BIMMP also includes the ability for the County to input construction quantity and unit cost data, allowing the County to program bridge projects based on allocated budget amounts. The program also includes various filters, including eligibility under Highway Bridge Program (HBP), condition rating (poor, fair, good,) and age of the bridge structure. With all the information provided within the database, the County staff is able to prioritize and deliver bridge maintenance and capital improvement projects more efficiently.