Test a car-light street for 90 days, with the measurements published

The problem: arguments about closing or calming a street are usually fought with predictions, so the loudest voices win.

The proposal: run a time-limited trial, say 90 days, with success measures agreed before it starts. Measure air quality and noise, travel times for people walking, cycling, using buses and driving, shop footfall and sales, and resident satisfaction. Publish a baseline, publish interim results, and publish the end-of-trial decision rule in advance, for example "extend if at least three of five measures improve and none worsens badly".

Who acts: the local authority runs it; local traders and residents help choose the measures; an outside group, such as a university, checks the numbers.

Costs and trade-offs: a trial is cheaper than a permanent build and easier to reverse, but a temporary scheme may behave differently from a permanent one, so treat results as evidence, not proof.

First step: pick one street, write the measures and the decision rule, and share them before anything is moved.