PLENARY SESSION 4: A Critical Look at Working Platform Design-Paper

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The paper reviews the EFFC/DFI Guide to Working Platforms, Second Edition (2025), arguing that it lacks practical guidance for designers, particularly those new to the subject. The authors explain that working-platform design involves a strong granular layer over weaker ground, and that bearing-capacity calculations rely on approximations because no simple exact solution exists for the layered system.<br /><br />A central concern is the use of high-friction-angle platform materials. Their strength strongly affects predicted capacity and platform thickness, so small errors in friction angle can produce substantial design changes. The authors emphasize the need for suitable testing, sensitivity analysis, and careful specification.<br /><br />They distinguish complete design methods—which combine rig loading, a bearing-capacity model, and a safety approach—from calculation methods that estimate capacity alone. In their view, BR470 is the only established complete method, with components calibrated together against benchmark platform thicknesses. Its components should not be mixed with other loading or calculation approaches without equivalent calibration. They also question whether the TWf method’s model accuracy and safety factors have been adequately validated.<br /><br />The paper raises concerns about rig-track loading data and the Guide’s tables, and discusses the limitations of plate-load and other field tests. It notes that platform variability may make limited testing unreliable, while ongoing research is exploring the use of light-weight deflectometers.<br /><br />The authors further stress that temporary status alone does not justify reduced safety margins, and that designs must also address global stability, groundwater, ramps, and edge-related exclusion zones. They conclude that substantial revisions to the Guide are needed, alongside improved testing methods and clearer advice on calibration and design practice.

Keywords

working-platform design

EFFC/DFI Guide

bearing capacity

granular layer

friction angle

safety factors

BR470 method

rig-track loading

plate-load testing

design calibration