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Dr. Michel Ghosn
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This report develops a Load and Resistance Factor Rating (NYS-LRFR) methodology for New York bridges. The methodology is applicable for the rating of existing bridges, the posting of under-strength bridges, and checking Permit trucks. The proposed LRFR methodology is calibrated to provide uniform reliability index values for all applications. The reliability calibration of live load factors is based on live load models developed using Truck Weigh-In-Motion (WIM) data collected from several representative New York sites. The live load models provide statistical projections of the maximum live load effects expected on New York bridges.

A new set of NYS Legal Trucks along with appropriate live load factors are proposed for performing Operating Level Ratings of existing bridges. Permit load factors are calibrated for unlimited crossings of divisible loads as well as single crossings and unlimited crossings of non-divisible loads. An equation is proposed for determining Posting weight limits for bridges with low Rating Factors as a function of the effective span length. It is proposed that different posting weights be imposed for single unit trucks and semi-trailer trucks.

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