The Voorhees law of traffic: when overtaken slow cars seem to always catch up at a red light

Maths researcher explains seeming inevitability of phenomenon experienced by many motorists It is a situation experienced by many motorists: one driver overtakes another only to find the slower car is right behind them when they reach a red light. Now a researcher has used mathematics to reveal why the situation feels inevitable. Dr Conor Boland from Dublin City University has called his work “The Voorhees law of traffic”. The name is a nod to the character Jason Voorhees from the American horror film franchise Friday the 13th. “I always thought of him because he seems to just walk everywhere … His victims are running away, they’re sprinting, but he just catches them,” Boland said. However, in the case of cars it is traffic lights rather than stones or tree branches that prevent the “escape” of the faster individual. Writing in the journal Royal Society Open Science, Boland explains that as two cars travelling at different speeds encounter a traffic light, the spacing between them can either increase, stay the same, partly decrease or be completely lost, depending on the colour of the traffic light, its duration, the time advantage of the faster car and the overall time it takes fo