To evaluate the reliability of a bridge, the maximum traffic load that is expected to occur during bridge operation needs to be known. The distribution of vehicle distances in congestion is an important parameter that co-determines the expected maximum traffic load effect. However, up to now only very few data exist that address this issue. In the presented study, measurement of vehicle distances was performed using an innovative camera solution called “Mobility Observation Box” (MOB). Video data acquired at two highway sites was processed to detect vehicle trajectories and evaluate vehicle distances. This data served to determine probabilistic distributions of vehicle distances. To separate behavior in congestion from the flowing traffic, the evaluation was executed in several velocity ranges. A bimodal distribution was fitted to describe the vehicle distances in particular velocity ranges. The presented paper describes methodology of acquiring more accurate data on distances of vehicles in congestion and shows first results of an application. The applied methodology seems useful – after performing more measurements at different sites – to provide vehicle distance distributions for the assessment of traffic loads on bridges.