Au fil des ans, certains incidents ont permis aux autorités municipales d'apprendre que des marchandises dangereuses, toxiques et même parfois radioactives, des isotopes médicaux par exemple, traversaient régulièrement leur territoire sans qu'elles en soient informées.
Over the years there were a number of incidents where it came to the knowledge of the municipal governments that on a regular basis certain dangerous goods, toxins, and in some cases even radioactive material such as medical isotopes, were moving through their jurisdictions and they had no idea it was happening.