Proverbially, there are lies, damn lies, and what? The time-honoured answer is not ‘the outputs from traffic models’....

We should be on guard against the way numbers are used to make a case. The numbers themselves may be accurate, and their use technically truthful; but the story that they’re used to tell may be partial or even disingenuous. Thus, for example, a reduction in the number and severity of injuries arising from collisions in a given street may mask (and be used to mask) a worrying increase in the number and severity of injuries sustained by a particular user group, says Jhn Dales...