Examining the Effect to Highways and Structures by Vehicles Equipped with Lift Axles

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The rise in Lift Axle Trucks in Maryland Roadways has brought attention to truck policies and regulations. A lift axle is an additional axle located on the truck that has the ability to be raised or deployed based on the Gross Vehicle Weight or the weight of cargo carried by the truck. Lift axles allow the truck to carry substantially higher payloads or cargo for a small increase in vehicle cost. There is much concern in the lift axle operation (the rise and deployment) based on weight, it could have a significant effect on the condition of pavement and bridge structures. This research study examined the federal and state truck regulations as well as lift axle truck configurations. Furthermore, based on truck digital weight and size data, the study explored the behavior of pavement and highway bridges based on the rise and deployment of lift axle, punching shear, yield line analysis as well as girder analysis and pavement damage. Results show that high rear tandem axle weights will have a higher effect on pavement and bridges than compared to tridem rear axle truck configuration (single unit truck with axle down) due to the loads being more distributed.