Weight Limit For Motor Non-Regulated Vehicles


ROD-IS is using its expertise in WIM and Load modelling in providing input into the regulations which govern the use of particular vehicles on the Irish Road Network. Using an Irish Weigh in Motion (WIM) database collected in 2014, this recently completed project for the Irish National Road Authority (NRA) was performed to assess the effects of amending the Road Traffic (Construction and Use of Vehicles) Regulations (S.I 5/2003, as amended) in order to include Gross Vehicle Weight (GVW) limit regulations for a number of specific vehicle configurations on general road bridges, masonry arch bridges and pavements. The general road bridge assessment was performed by carrying out statistical extrapolation for characteristic 1000-year load effects for 143 typical bridge configurations. The vehicle types considered included;


  • 5-axle rigid vehicle

  • 4-axle trucks drawing 2-axle trailers

  • 3-axle trucks drawing 3-axle trailers.


For the 5-axle rigid vehicle ROD-IS were required to derive a gross vehicle weight (GVW) limit as well as a specific configuration as these were not available in the WIM data. For the 4-axle trucks drawing 2-axle trailers the effect of moving from an allowable GVW of 42 tonnes to 46 tonnes was assessed. For the 3-axle trucks drawing 3-axle trailers the impact of increasing the allowable GVW from 44 tonnes to 46 tonnes was assessed. As a supplementary project, ROD-IS staff cleaned and screened the database to ensure it was appropriate for the study and to remove any suspect records.