We have developed a model of traffic-related particle behaviour in a street canyon and in the near vicinity that accounts for the particle dynamics, with robust insight into the evolution and fate of traffic induced multicomponent ultrafine particles (UFP) in the presence of Semi-Volatile Organic Compounds (SVOC). We evaluate the UFP evaporative potential and composition changes of multicomponent organic particle in realistic atmospheric conditions and compare our results with observations from London, UK. Evaporation is found to be very fast in reducing particles diameter for nucleation mode particles. 97% volatile material on the surface of nucleation mode praticles is required to explain the observed behaviour of particles diameter reduction. Findings for the Aitken mode are inconclusive due to the variety of sources and emissions not directly linked with traffic. This work is part of the FASTER project, sponsored by the European Research Council (ERC).