How to calculate the rating factor (RF) A1 = Factor for dead loads A2 = Factor for live load C = Capacity of the bridge D = Dead load effect I = Impact factor L = Live load effect C – A1 * D RF = A2 * L*(1 + I) It is usually expressed as a (rating) factor (RF) of a defined vehicle OR as a gross tonnage for a defined vehicle axle configurationīasic Equation for Calculating the Rating Factor (RF) A load rating can be expressed in terms of a “rating factor” for a particular vehicle. What Is Bridge Load Rating? The safe live load carrying capacity of a highway structure is called its load rating. Consequently, even though pedestrian and railroad structures fall under the definition of “Bridge”, and they are inspected and inventoried, they are not load ratedĪASHTO HS 25 Truck (current Ohio design load) HS 25 40k 40k 10k Varies (14’-30’) 14’ĪASHTO HS 20-44 Truck (still to be used for Ohio load ratings) HS 20-44 8k 32k 32k Varies (14’-30’) 14’

Permit Loads & Superloads Note: The Feds only require highway loads to be used for load rating.

Superimposed dead loads (barriers, overlays, utilities, etc.).

There are Two Primary Types of Loads used in Load Ratings?

Ohio Department of Transportation (ODOT) Definition (based on the Ohio Revised Code): A Bridge is ANY structure that… 1.) is on, above, or below a highway AND 2.) Is greater than or equal to10’-0” (measured the same way as in the FHWA definition).

Federal Highway Administration (FHWA) Definition: A Bridge is ANY structure that… 1.) is erected over a depression or obstruction (water, highway, railway, etc.) AND 2.) has a track or passageway for carrying traffic or moving loads AND 3.) has an opening greater than 20’-0”(measured along centerline of roadway between undercopings of abutments or spring lines of arches, or extreme ends of openings for multiple boxes it may also include multiple pipes, where the clear distance between openings is less than half of the smaller contiguous opening).ODOT BRIDGE LOAD RATING A basic how and why overview

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