Institute for Transportation

A recent NCHRP project 20-07/task 122 study by Dr. Dennis Mertz of a small sample of bridges reported that LRFR average about 7% higher than LFR for design-load inventory ratings. Our findings indicate that this would cause less than a 2% reduction in national eligible deck area on deficient bridges if all NBI inventory ratings were suddenly changed to LRFR. Other variations in LRFR vs. LFR, and the resultant impact on eligible deck area on deficient bridges, were evaluated. The findings are presented in the attachments. The FHWA does not intend to require the States to re-rate the large inventory of older structures that have already been rated by ASR or LFR with LRFR methods, but rather to allow the States to re-rate existing structures with LRFR per their own policies. Only structures designed or reconstructed using LRFD would be required to be rated using LRFR.