Traffic Signal Installation Day

What Is Traffic Signal Installation Day?

Every August 20th is "Traffic Signal Installation Day" (交通信号設置記念日, Kōtsū Shingō Setchi Kinenbi) in Japan. On August 20, 1931, Japan's first automatic three-color traffic signals — red, yellow, and green — were installed at 34 intersections in Tokyo, including the famous Ginza 4-chōme crossing and Kyōbashi crossing. The introduction of automatic traffic signals marked a watershed in Japan's urban traffic management, imposing order on streets increasingly overwhelmed by automobiles, bicycles, rickshaws, and pedestrians.

Traffic Control Before Signals

Before the 1931 signal installation, traffic at major Tokyo intersections was controlled manually by police officers (交通巡査, kōtsū junsa), who directed the flow of vehicles and pedestrians by hand signal and whistle. As automobile traffic grew through the 1920s — Japan's automobile population roughly doubled in that decade — manual control became increasingly inadequate. The electric traffic signal, already in use in the United States since 1914 and in European cities since the early 1920s, offered a scalable, consistent solution.

Japan's Traffic Signal Network Today

Japan now operates approximately 210,000 traffic signals — one of the world's densest networks relative to road length. Japanese traffic signals incorporate numerous features that have become international standards: pedestrian signals with audio tones for visually impaired users, countdown timers showing time remaining before signal change, and protected left-turn phases (Japan drives on the left). Major intersections in urban areas now use sophisticated traffic management systems that adjust signal timing in real time based on traffic density.

Road Safety and Traffic Engineering

Japan's traffic signal network is part of a broader traffic safety infrastructure that has achieved remarkable results. From a peak of nearly 17,000 traffic fatalities in 1970, Japan reduced road deaths to under 2,500 by the early 2020s — one of the lowest rates among large developed nations — through a combination of improved road engineering, vehicle safety standards, traffic signal optimization, and sustained public education campaigns.

Fun Facts

• Ginza 4-chōme: The Ginza 4-chōme crossing — one of the sites of Japan's first traffic signals in 1931 — remains one of Tokyo's busiest and most famous intersections, used by hundreds of thousands of pedestrians daily.
• LED signals: Japan has converted most of its traffic signals to energy-efficient LED technology, reducing energy consumption dramatically while improving signal visibility in bright sunlight and adverse weather.