Detecting and distinguishing vehicles with a maximum permissible weight up to 3.5 tonnes, among others required in the TLS 8+1 classification, due to the similar dimensions of selected vehicle groups is often a relatively complex process that requires the use of extensive classification methods. Detection of commercials vans is particularly important. Their parameters are similar to lorry vehicles and their incorrect classification, eg in systems of weighing vehicles in motion, results in the lack of information on exceeding the permissible total weight. The article presents the selected classification method and its effectiveness