Load spectrum for utility trenches in the footway

Abstract

Local authorities are concerned about the adoption of cable television networks after they reach two years of age. Concerns have been raised about the shallow burial depth (250 mm to the crown for ducts in footways), the longevity of the reinstatement, and the possibility of future damage to footways under vehicle loading. The aim of this research was to develop a realistic load regime for footway utility trenches. This was achieved by parking surveys counting the type (HGV, LGV or car) and frequency of footway loading incidents. The final output from the parking surveys was used to derive a load spectrum for future application to laboratory trench box tests. From these daily survey results, extrapolated worst-case load regimes for a 20 -year design life were derived to assist engineers in their assessment of cumulative footway damage.