Area-Wide Traffic-Calming Zone 30 Policy of Japan and Incidence of Road Traffic Injuries Among Cyclists and Pedestrians.

Objectives. To quantify the impact of the "Zone 30" policy introduced in September 2011 on the incidence of cyclist and pedestrian injuries in Japan.Methods. This was an interrupted time-series study. We used the data of cyclist and pedestrian injuries recorded by the Japanese police between 2005 and 2016. We evaluated the monthly number of deaths and serious injuries per person-time on narrow roads (width < 5.5 m, subjected to the policy) compared with that on wide roads (≥ 5.5 m) to control for secular trends. We regressed the injury rate ratio on 2 predictors: the numbers of months after January 2005 and after September 2011. Using the regression results, we estimated the number of deaths and serious injuries prevented.Results. There were 266 939 deaths and serious injuries. By 2016, the cumulative changes in the rate ratio spanned from -0.26 to -0.046, depending on sex and age, and an estimated number of 1704 (95% confidence interval = 1293, 2198) injuries were prevented.Conclusions. The policy had a large preventive impact on cyclist and pedestrian deaths and serious injuries at the national level.