A Review of Working Platform Design

The publication of BR470 in 2004 provided a major step forward in formalising the design of working platforms for tracked plant. However, since that time limitations in the design method have become apparent. A notable limitation is its stated inapplicability to clays of shear strength less than 20kPa. It is also generally considered to underestimate the effect of geogrid reinforcement, which resulted in a review document in 2011 permitting the use of alternative design methods, as well as to overestimate the stone requirement on granular formations. The use of BR470 is reviewed in this Paper and modification factors derived to allow its use with clays of all strength, as well as other modifications which improve the effect of geogrid reinforcement and reduce the stone thickness requirement for granular formations. The modifications have been based on extensive analyses using the program LimitState:GEO for both cohesive and granular formations, as well as through review of published data.