National Highway Traffic Safety Administration May 11, 2009 – Federal Register Recent Federal Regulation Documents

This purpose of this report is to determine the effect of rear turn signal color on the likelihood of being involved in a rear-end crash. Federal Motor Vehicle Safety Standard No. 108 allows rear turn signals to be either red or amber in color. The primary conclusion is that amber rear turn signals are 5.3% more effective than red rear turn signals at preventing involvement in crashes where a careful driver would typically use the turn signals. The result is shown to be statistically significant and consistent with other published analyses on the influence of rear turn signal color.