Bridge inspection program
Through the Bridge Inspection Program, crucial data for each bridge is gathered. General data such as the bridge location; the member’s types, materials, and sizes; and the bridge spans and widths does not change from report to report.
The condition of the bridge members, however can and does change from report to report. This is the most important part of the report. It must be carefully reviewed to determine if and where any changes have occurred. These inspections are conducted every two years to track the rate of deterioration and to find any surprise changes before they can affect the safety of the bridge.
Bridge management program
The next step is to analyze the data and the recommendations in the bridge inspection reports. Some bridges only have a few minor repair items. These repair items are prioritized on the severity of the individual repair. Other bridges may have multiple repair items. These are the bridges that may be considered candidates for rehabilitation or replacement.
The Bridge Management Program is a tool that is used to analyze and prioritize those bridges with multiple issues for rehabilitation or replacement. It takes information from the Bridge Inspection Program (such as the structural condition of deck, superstructure and substructure; scour condition; lane widths; average daily traffic; approach road condition; waterway adequacy; and the bridge posting) and computes a single numerical rating for each bridge in the county.
This rating gives a starting point for choosing the bridges to be rehabilitated or replaced. Other factors such as the historical status of the bridge, or that the bridge provides the only access to a community, are not considered in the computer program. These factors can be more important than the input data and override the computer generated priorities. Therefore, the Bridge Management output must always be considered as a first cut tool, not an absolute rating.
Bridge rehabilitation program
The projects can be divided into four major groups: bridge maintenance, bridge repairs, bridge rehabilitation and bridge replacement.
Bridge maintenance items
Bridge maintenance items are tasks that are completed to maintain the overall current condition of the bridge. These tasks include power washing decks and beam seats to remove winter salt treatment residue, spot painting steel, trimming vegetation, removing trees that are too close to bridges, replacing expansion joint seals, replacing/tightening bolts, etc. These projects require minimal design work and are routinely handled by the Highways’ Bridge Crew.
Bridge repair items
Bridge repair items are minor repair tasks performed to improve the condition of a deteriorated member, such as patching a spalled area (pothole) in the deck, repairing a deteriorated beam, replacing a section of the traffic barrier, repairing a spalled abutment, replacing a minor bridge member, etc.. These projects require some design effort by our In-House Engineering forces but the work is generally still completed by the Highways’ Bridge Crew.
Bridge rehabilitation items
Bridge rehabilitation items include substantial repair or full replacement of one or more of the major members of the bridge, such as the deck, superstructure, or substructure units. This category also includes construction of stream scour countermeasures to prevent fast flowing streams from damaging or destroying bridges during major storms. In-house engineering staff will provide the design services for the minor rehabilitation projects and consultant engineers are hired to complete the more complex projects. Contractors generally will be hired to complete the construction of these projects.
Total bridge replacement
Total bridge replacement means the entire existing bridge is removed and replaced with a new bridge that may or may not be similar to the existing bridge. Consultants are almost always hired to design these projects because of the large investment of time that is required. Contractors are also almost always hired to complete these projects for the same reasons.
Most projects are funded solely by Harford County with no outside sources. The county does, however, seek federal funding for major bridge rehabilitation projects and bridge replacement projects that meet the federal program qualifications.