In the UK, the length of a goods carrying vehicle is limited to a maximum of 16.5 m for a standard articulated vehicle and 18.75 m for a draw-bar combination. This research has investigated the environmental, economic and practical impacts of expanding the volumetric carry capacity by increasing maximum length of vehicles to 25.25 m, while maintaining the maximum gross weight at the current UK limit of 44 tonne. The scope is limited to the consideration of 25.25 m vehicle variants that are currently in use in the Netherlands. The investigation was based on a variety of techniques that included bench research and case study modelling. It concludes that, although the picture is complex and there are a number of operational issues to be addressed, the introduction of high-capacity vehicles (HCVs) to the UK would yield valuable environmental and financial benefits at vehicle and operator level, provided that vehicle utilisation levels do not deteriorate as compared with current fleet. At the national level, financial benefits would be partially offset by infrastructure costs and there is some risk of environmental benefits being partially eroded by modal shift – but on both measures a net benefit is highly likely to remain. In addition, provided that appropriate risk control measures are adopted, use of HCVs is highly unlikely to have an adverse impact on road safety.