Assigned Load Ratings

Per the September 29, 2011 FHWA Assigned Load Rating Memo, FHWA has determined that the Inventory and Operating level ratings may be assigned based on the design load when:
  1. The bridge was designed using either the AASHTO Load and Resistance Factor Design (LRFD) or Load Factor Design (LFD) methods to at least HL-93 or HS-20 live loads, respectively. The engineer shall provide or verify that the proper design plans showing the required design load and design method are available in the Bridge Inspection Management System, AssetWise; and
  2. The bridge was built in accordance with the design plans; and
  3. No changes to the loading conditions or the structure condition have occurred that could reduce the inventory rating below the design load level; and
  4. An evaluation has been completed and documented, determining that the force effects from State legal loads or permit loads do not exceed those from the design load; and
  5. The checked design calculations, and relevant computer input and output information, must be accessible and referenced or included in the individual bridge records
TxDOT’s Load Rating Statement (form 2495) for assigned ratings is applicable when the following conditions are met:
  1. The bridge must be designed using AASHTO Load and Resistance Factor Design (LRFD) or Load Factor Design (LFD) methods to at least HL-93 or HS-20 live loads, respectively.
  2. The principal structural elements of Items 58 (SNBI: B.C.01), 59 (SNBI: B.C.02), 60 (SNBI: B.C.03), and 62 (SNBI: B.C.04) must have a condition rating greater than or equal to 5.
  3. The bridge elements in their current state continue to maintain structural capacity equal to the original design.
For assigned load ratings, the coding for items 63 (SNBI: B.LR.04) and 65.1 (SNBI: B.LR.04) must be "C - Assigned rating based on LRFD reported in tons" (SNBI: AR) or "A - Assigned rating based on LFD reported in tons" (SNBI: AR) respectively.
Prestressed beams designed with AASHTO Standard Specifications 1961 or later included strengths checks and are considered to meet the requirements for Load Factor Design.