PALS 2.0 User's Guide

Full-Text PDF


E.G. Fernando

Publication Date:

October 1997


PALS is an acronym for Program to Analyze Loads Superheavy. Gross vehicle weights associated with superheavy load moves range from 1112 kN to more than 8896 kN and include loads like dragline components, off-shore pipe laying equipment, oil pressure vessels, and electric transformers. The number of superheavy load permit applications has increased over the years. Before a permit can be issued, TxDOT needs to determine whether the proposed route is structurally adequate to sustain the superheavy load. PALS is a tool for conducting this assessment. It incorporates an incremental, non-linear layered elastic pavement model for predicting the induced pavement response under surface wheel loads. Predicted stresses under a superheavy load are used with the Mohr-Coulomb yield criterion to evaluate the potential for pavement damage prior to the superheavy load move. PALS Version 2.0 is a major revision of the original program developed in Project 0-1335, "Movement of Superheavy Loads Over the State Highway System." Significant enhancements include the development of routines to evaluate the edge load condition and to determine the failure wheel load for a given pavement structure. The former modification is used to evaluate the potential for edge shear failure on moves where the wheel loads will travel close to the edge of a given pavement with unpaved shoulders. The latter modification is used in identifying alternative trailer configurations to prevent pavement damage during superheavy load moves. Instructions in the operation of PALS 2.0 are provided in this guide.

Report Number:



Superheavy Loads, Pavement Evaluation, Pavement Response Modeling, Nonlinear Material Behavior, Mohr-Coulomb Yield Criterion

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