Basic Information

About Bridge Load Rating

Bridge load rating determines the safe load-carrying capacity of a bridge. The Inventory Rating represents the maximum permissible load for indefinite traffic, while the Operating Rating represents the absolute maximum permissible load.

Bridge Geometry

Material Properties

Loading Conditions

Member Properties

Load Rating Results

Load Rating Factor (LRF)

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Capacity / Demand ratio for the bridge

Inventory Rating

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Conservative rating for indefinite traffic

Operating Rating

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Absolute maximum permissible load

Safety Status

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Bridge safety assessment

Vehicle Compatibility

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Interactive Guide

Bridge load rating determines the safe load-carrying capacity of a bridge under various loading conditions. It helps transportation departments and engineers decide if a bridge needs repair, strengthening, or load posting.

The rating is typically expressed as a Load Rating Factor (LRF) which is the ratio of the bridge's capacity to the demand from applied loads. Values greater than 1.0 indicate the bridge can safely carry the load.

Inventory Rating represents the maximum permissible load level that can safely utilize the bridge for an indefinite period. It uses more conservative assumptions and factors of safety.

Operating Rating represents the absolute maximum permissible load level to which the bridge may be subjected. While safe, using the bridge at this level continuously may reduce its service life.

This calculator follows the AASHTO Manual for Bridge Evaluation standards for load rating calculations.

Key standards applied:

  • LRFD Bridge Design Specifications (for LRFD method)
  • Standard Specifications for Highway Bridges (for ASD method)
  • Live load models: HS20, HL93, etc.
  • Impact factors and distribution factors as specified

  1. Enter basic bridge information (type, design method)
  2. Provide bridge geometry (span length, width)
  3. Input material properties (steel, concrete, etc.)
  4. Specify loading conditions (dead load, live load model)
  5. Enter member properties (section modulus, moment of inertia)
  6. Click "Calculate Load Rating" to get results
  7. Review Inventory and Operating ratings
  8. Check vehicle compatibility if needed
  9. Export or print results for your records