Traffic simulation experiments were carried out for an urban road network to explore the effect of road vehicles’ individual traffic congestion avoidance efforts, in which on-board visual line-of-sight (LoS) exteroceptive sensors (ECSs) and related on-board traffic congestion detection (OTCD) capabilities are put to use on the network level traffic situation. OTCD requires a visual LoS constellation between the subject vehicle and some vehicles in the vehicle queue ahead. The experiments concern themselves with the comparison of undisturbed, disturbed and mitigated traffic. PTV Vissim traffic simulator was used in the experiments. The process of congestion detection, avoidance and mitigation was tentatively modelled via proxy parameters. Two series of experiments are reported herein. A new approach to route planning has been identified and earmarked for future research.