A bridge shall have calculated load rating if it is not eligible for Assigned or Assumed Load Rating. Traditionally Inventory or Operating Ratings were determined using either Load Factor Rating (LFR), Load and Resistance Factor Rating (LRFR), or Allowable Stress Rating (ASR) methods. The selection of calculated load rating method shall be in compliance with the FHWA memo of “Bridge Load Ratings for the National Bridge Inventory” dated on 10/30/2006.

LFR or LRFR may be used for most bridges. ASR should be used only for timber and masonry bridges.

A Load Rating Summary Sheet should be completed for all calculated load ratings.