Guide to Design of Culway - WIM

Spectrum of Bridge fatigue assessments need continuous and cumulative data to
provide the whole operating traffic load; including truck weight, vehicular configuration
and frequency of the traffic that uses any given structure. Bridge engineering studies in
Europe have shown that the 50 to 75% quartile of stress range distribution on a bridge
has the highest impact on bridge fatigue, long term changes to this distribution only
affects future lifespan not the elapsed one. Overestimations or crude assumptions will
heavily penalise bridges sensitive to fatigue. Bridge lifetimes can be greatly extended
and significant cost savings may be made where the load limits and density can be
reduced.
Culway data can be used to assist in the design of pavements in particular repair layers
to existing pavements as the data provided by Culway can give the Designer an
accurate picture of historical and current pavement loadings, which should lead to an
adequate and cost effective design.
Grossly overloaded trucks cause accelerated pavement wear, Culway data allows the
Asset Manager to budget and plan for future pavement reconstruction. Knowing the level
and frequency of overloading on a road will provide a more accurate estimate of
pavement life, thereby providing, improved safety, serviceability and cost savings to the
road owner.
It should be noted that Culway data is not accurate enough for enforcing axle-loading
regulations.
MAIN ROADS Western Australia
Guide to the Design of Culway.doc
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