Truck Driver's Guidebook
Bridge Gross Weight Formula

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This vehicle has a bridge of 14'. Using the B/F chart, check the distance of 14' for two axles, finding a gross weight of 40,000 lbs. If this vehicle exceeds the formula weight of 40,000 lbs., the vehicle does not qualify for the bridge formula so only designated weights would apply.

This vehicle has a bridge of 24' between axles 1 and 3. Using the B/F chart, this vehicle would be allowed a gross weight of 54,000 lbs. If this vehicle exceeds the B/F gross weight of 54,000 lbs., the vehicle does not qualify for the bridge formula so only designated weights would apply.

This vehicle has a bridge of 21' between axles 1 and 4. Using the B/F chart, this vehicle would be allowed a gross weight of 56,000 lbs. If this vehicle exceeds the B/F gross weight of 56,000 lbs., the vehicle does not qualify for the bridge formula so only designated weights would apply. The group bridge between axles 2 and 4 is 8'.  Using the B/F chart, 8' would give this group 34,000 lbs. when designated loading is 13,000 lbs. per axle or 39,000 lbs. for the group - AXLE WEIGHTS WILL NOT BE LOWERED ANY LESS THAN DESIGNATED WEIGHTS.  If the bridge between axles 2 and 4 was 9', the group weight would be 42,500 lbs.

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** *The bridge formula allows up to 20,000 lbs. per single axle, if the vehicle is equipped with large enough tires.  Steering axle weights will vary depending on the gross weight of the vehicle.

Due to frequent changes in federal and state regulations, the Michigan Center for Truck Safety cannot ensure the accuracy of the material contained in the Guidebook beyond the date of publication. For current information, contact the Center at (800) 682-4682. This document is not intended for legal purposes.