923 series Bullet Train Doctor Yellow

Data (as of 5 Apr 2025)

History

The 923 series is the incumbent Doctor Yellow, a famous measurement train not only in Japan but also in the world. The 923 series is based on 700 series, and two seven-carriage units were introduced. The 923 series monitors track and overhead wire conditions on Tokaido and Sanyo Shinkansen, but not on Kyushu Shinkansen.

Since Tokaido Shinkansen is the busiest high-speed rail in the world where up to 17 trains per hour on each direction run at a speed of 270 km/h (168 mph), the 923 series is designed to carry out measurement at the same speed. Even after JRs installed track monitoring devices to some N700 series in 2008, Dr Yellow was still necessary for precise assessments. Due to its distinctive appearance and rarity, the 923 series has been highly popular across the country.

JR Central and JR West have used the series respectively and those units have taken turns working every three months, but JR Central's unit retired in January 2025.

Current Operations & Future Prospects

The 923 series is a measurement train so that it runs as required. Generally, the measurement work takes place three or four times a month, and there are two patterns of fixed timetable.

JR West will retain it until around 2027. There will be no successor to the 923 series as JR West will install inspection and monitoring devices to ordinary N700S series units, indicating that the history of Dr Yellow will end then.