Ensuring the safety of Oregon’s bridges
The collapse of the I-5 bridge over the Skagit River in Washington has directed attention to the health of the nation’s bridges and led people to ask whether other bridges — including those in Oregon — could face the same fate.
Oregon’s bridges are in relatively good condition thanks to significant investment in bridge repair and replacement projects. The $2.46 billion Oregon Transportation Investment Act (OTIA) III package passed by the Oregon Legislature in 2003 allocated $1.3 billion to state highway bridges and $300 million to local bridge projects. Under the OTIA III State Bridge Program, 263 bridge repair and replacement projects have been completed and open to traffic, seven are under construction and one bridge remains in the design phase. The program was designed to strengthen the state’s aging transportation infrastructure. Beyond the bridge funding provided by OTIA III, Oregon invests tens of millions of dollars annually in bridge maintenance, repair, and replacement.
More than 20 of these structurally deficient bridges are being repaired or replaced through the Statewide Transportation Improvement Program or other specific programs through 2015. About 15 bridges become newly classified as structurally deficient each year. This is expected to increase to 23 additional structurally deficient bridges each year on average over the next ten years. As a result, over the long term the condition of Oregon’s bridges will deteriorate significantly unless sufficient funding for bridge preservation and repair activities becomes available.
ODOT inspects bridges at least once every two years – more often as the condition of the bridge declines. ODOT uses inspection results to help prioritize bridge repair investments. If a bridge is deemed unsafe, it is immediately closed to travel. Often, ODOT must restrict the weight or size of vehicles a bridge can carry. A restriction does not mean the bridge is unsafe.
Attention has focused on the truck that hit the Skagit River Bridge, triggering its collapse. Bridges in Oregon are hit from time to time, usually due to driver error. When a bridge is hit, ODOT inspectors are immediately dispatched to assess the damage, and actions are taken to mitigate future damage. For example, after the OR 99E Harrisburg Bridge was hit by a truck, ODOT deployed an over-height warning system that uses an infrared beam and signs with flashing lights to stop trucks that would damage the structure.
Oregon’s oversize truck permit system also minimizes the chance for a bridge to be hit by a truck. An oversized load – over-height, over-width or overweight – traveling through Oregon must have a permit issued through ODOT’s Motor Carrier Transportation Division. Highly trained staff uses a database to route trucks safely based on their size and weight. ODOT’s Motor Carrier Transportation Division and Highway Division work hand in hand to ensure the database is up-to-date and inclusive. The database includes vertical clearance information for bridges, overpasses, tunnels and other infrastructure. The measurements are updated by ODOT staff on a regular basis, including whenever a new bridge is built or when a project is completed that might change the clearance, such as a new layer of pavement under a bridge.