Social norms as a cost-effective measure of managing transport demand: Evidence from an experiment on the London underground

Demand for public transport in cities has been and is projected to increase, putting existing transport networks under increasing strain. Nudging passengers to behave in certain ways through the creation of a salient social norm has the potential to be a cost-effective mechanism to manage transport demand. Transport for London (TfL) implemented in the second half of 2017 an experiment on one of its busiest metro train platforms. The platform surface was painted to highlight the exact location of the train doors once it comes to a full stop and to direct passengers to wait in parts of the platform that would not obstruct passengers from alighting from the train and leaving the platform. Drawing on millions of individual train waiting times, we estimate the effect of this intervention to change passenger behaviour on the platform on train waiting and delay times. We use different sets of assumptions about what the counterfactual change in waiting and delay times would have been in the absence of the intervention. The intervention has reduced train waiting times by up to 6.6%. This reduction came about mainly through reducing delay times of trains once they are delayed. The reductions tend to occur during peak traffic hours. The implied cost-savings amount to a return of £6 per £1 investment.