Child pedestrian deaths: sensitivity to traffic volume--evidence from the USA.

STUDY OBJECTIVE In case centred epidemiological studies, traffic volume has been shown to be a potent risk factor for child pedestrian injuries. Nevertheless, over the past two decades child pedestrian death rates have fallen in many countries despite large increases in traffic volumes, suggesting that other factors are responsible for the long term decline in death rates. This study aimed to investigate the relationship between short term changes in traffic volume and child pedestrian death rates. DESIGN The relationship between child pedestrian death rates and traffic volume in the USA for the period 1970-88 was investigated. Trends in death rates and in traffic volume were removed by the time series method of differencing. RESULTS After removing the long term trends, there was a close relationship between the year to year variation in traffic volume and the year to year variation in the child pedestrian death rate. Most notably, in the two periods when traffic volume actually fell, the falls in the child pedestrian death rate were considerably larger than those seen at any other time. Overall, decelerations in the rate of increase in traffic volume were accompanied by accelerations in the rate of decline in the child pedestrian death rate. CONCLUSION While other factors may determine long term trends in child pedestrian death rates, they are very sensitive to short term changes in traffic volume. Public policy changes which limit the growth in traffic volume have the potential to accelerate the decline in child pedestrian death rates.