TRL assessed the potential for casualty reductions in collisions between Heavy Goods Vehicles (HGVs) and vulnerable road users, if European Union (EU) legislation made it a mandatory requirement for close proximity mirrors (Class V) to be fitted to all new and existing goods vehicles above 7.5 tonnes. The study also investigated side-swiping accidents involving left hand drive (foreign registered) vehicles. The work included a detailed review of mirror legislation, previous research, injury and non-injury accident statistics from a number of different sources, computer simulations of HGV fields of view using different HGV and human models, an HGV driver questionnaire on the use of mirrors, and research into the numbers of HGVs, in the UK and EU member states, affected by any EU requirement to fit Class V mirrors. Further work with Kent Police investigated the numbers of side-swiping accidents involving LHD vehicles. A partial regulatory impact assessment was developed in conjunction with the results in this report. (A)