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TfL’s three-week tube escalator trial shows the value of experimentation in designing policy

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Londoners have recently had their ‘common sense’ upended thanks to TfL’s willingness to challenge one of our sacrosanct rules with an experiment.

As Ellie Violet Bramley explains in the Guardian (with lovely accompanying graphics) the overcrowding at Holborn Tube Station during the rush hour got some transport engineers thinking about how to move people through the station more quickly and safely. They suspected that the time-honoured London practice of standing on the right only – so those in a rush or wearing fitbits can walk up on the left – might not be helping things. Although it sounds counter-intuitive, TfL decided to experiment with asking commuters to stand on both sides of the escalator on a hunch (backed up by some modelling) that this would move everyone up from the platforms faster.

And during the three week trial it did. During the busiest hour of the morning rush one escalator carried 16,220 people compared to 12,745 on a standing-on-left-side-only day, an increase of over 25%.

Given the likely cost of other possible measures to reduce congestion in the aged tube system this small experiment could point the way to a relatively simple change which could save vast sums of money.

The impact of changes to the escalators at Holborn is enviably quick to manifest and easy to measure (although changing commuters’ behaviour is another story altogether). Our work, understanding the impact of policies on local economic growth, is complicated by the length of time programmes run, the delay in measurable impact, and the multiplicity of outputs and outcomes which may be desired.

But this experiment is a compelling reminder of the dramatic results that can sometimes be achieved by challenging conventional wisdom. Small experiments, when their results are properly evaluated, can sometimes tell us a great deal about what works better before committing public funding to new policies.