DFI / EFFC WORKING PLATFORM TASK GROUP TRACK PRESSURE FRS#2 & DESIGN METHODS FRS#3-PDF

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The DFI/EFFC Working Platform Task Group report evaluates methods for calculating track pressures and designing unreinforced granular working platforms for construction machinery. It supports development of the second edition of the Guide to Working Platforms, addressing the lack of a universal design standard and the safety risks posed by inaccurate loading assumptions and uncertain ground conditions.<br /><br />The report reviews established design approaches—including BRE BR470, CIRIA SP123 and TWf—and calculation methods such as load-spread, punching-shear, T-Value, Miller, DIN 4017, Okamura and Eshkevari. It compares their assumptions, safety factors, applicability and predicted platform thicknesses for cohesive and granular subsoils. Python scripts were developed and checked against published examples, while field and model-scale data were used to assess how predictions compare with observed performance.<br /><br />Results show substantial variation between methods: conservative approaches may require impractically thick platforms, while more economical methods can underestimate requirements in weak soils or under concentrated and cyclic loads. Field measurements also show that track pressures are often non-uniform, with high edge concentrations, and that settlements can increase over time. No single method is suitable for every situation.<br /><br />Platform friction angle and subsoil strength are decisive design inputs. Higher-quality, properly verified platform material and wider tracks can reduce required thickness, while groundwater can reduce bearing resistance. The report recommends thorough site investigation, cautious and verified parameter selection, realistic machine-specific track-pressure assessment, and in-situ quality testing. Designers should use each method within its stated limits and never combine favorable assumptions or safety factors from different methods. For very weak or complex ground, conservative design, reinforcement or advanced numerical analysis may be needed.

Keywords

working platforms

track pressure

granular platforms

unreinforced design

construction machinery

ground conditions

bearing resistance

design methods

subsoil strength

site investigation