Reduction of traffic accidents and improvement of road traffic produced by 5th five-year project for the installation and upgrading of traffic safety facilities (for ITS deployment in Japan).

Since 1966, Japanese Police have been promoting a project for installing and improvement of traffic safety facilities aiming at attainment of safe and smooth traffic. The effects are analysed for prevention of traffic accidents and attainment of smoother traffic by installing new signals and upgrading signals, which were investigated over 5 years from the 1991 fiscal year through the 1995 fiscal year throughout Japan. The effects of them are as follows: (1) new installation of traffic signals works to reduce occurrence of traffic accidents by 75% or more; (2) among upgrading to computer-controlled signals of existing traffic signals: (i) speed sensitive control (dilemma-eliminating control) by using speed sensor works to reduce encounter collision accidents by 61%; and (ii) split traffic adjustment by use of blue arrow signalling works to reduce occurrences of right-turn accidents by 46%; and (3) offset adjustment for smoother vehicle travels improves the travel time by 17 to 21% and reduces traffic congestion time duration at intersections by 29 to 33%.