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Load Rating

 

Load Rating

Load Ratings are performed to protect both the safety of traffic and the significant investment in the state’s bridge infrastructure. Knowledge of the capacity of each bridge to carry loads is critical for each function. A Load Rating that reflects the current condition of each bridge provides a valuable tool that is used in identifying the need for load posting or bridge strengthening and in making overweight-vehicle permit decisions. Load Ratings are also used in the bridge management system to prioritize bridge repairs and replacements.

ODOT Bridge Section has implemented the Load and Resistance Factor Rating (LRFR) method, based on the 2011 AASHTO Manual for Bridge Evaluation (MBE) with 2013 Interim Revisions. LRFR is a statistically-based, more accurate and defensible load rating than the previous method, now referred to as the Tier-1 Load Rating Procedures.

In the 2013 Interim Revisions of the MBE, the National Live Load Factors have been re-calibrated and are now very similar to the Oregon Specific Live Load Factors that are used for ODOT owned bridges. As a result, all bridges in Oregon (regardless of the owner) will be rated following the ODOT LRFR Load Rating Procedures. ODOT bridges will use the Oregon Specific Live Load Factors and all other bridges will use the re-calibrated National Live Load Factors. If a specific structure type is not currently covered in the ODOT LRFR Manual, contact ODOT’s Senior Load Rating Engineer (Jon Rooper) at (503)-986-3357 or at Jonathan.w.ROOPER@odot.state.or.us.

Resources for LRFR Load Rating Procedures