Doctor Yellow

is the nickname for a series of high-speed diagnostic trains that are used on JR Central's Tokaido Shinkansen and JR West's San'yō Shinkansen lines. The trains have special equipment on board to monitor the condition of the track and overhead wires, including special instrumented bogies and observation blisters. Line inspection is carried out at full speed, up to on the Tōkaidō Shinkansen and on the Sanyō Shinkansen. Doctor Yellow trains make three round trips between and Hakata Station every month. Depending on the day, trains follow the stopping pattern of either Nozomi or Kodama trains. A similar type of diagnostic train called East i is operated by JR East on the Tōhoku Shinkansen.

"Doctor" in the name "Doctor Yellow" refers to their test and diagnostic function, and "Yellow" refers to the bright yellow livery they are painted in. The original color scheme of yellow with a blue stripe (applied to the Class 921 track-recording cars) was created by reversing the colors (blue with yellow stripe) used by track-recording cars on Japan's narrow-gauge railways. Some Doctor Yellow sets are painted with a green waistline stripe rather than a blue one. In build and appearance, they resemble the production, passenger-carrying Shinkansen trains they are based on.

Because the schedule for this train is not made public, witnessing a Doctor Yellow in operation is a matter of chance. As a result, seeing one is said to bring the witness good luck or happiness. Railfans have set up websites and social media accounts to predict Doctor Yellow's arrival dates and times at stations along the route.

On 13 June 2024, JR Central announced that they would terminate use of Doctor Yellow trains on the Tōkaidō Shinkansen line in January 2025, with plans for farewell events – including commemorative train rides, displays, and souvenirs – to be announced at a later date. At the same time, JR West announced plans to retire their trains after 2027. They are scheduled to be replaced with commercial N700S Series Shinkansen trains that incorporate inspection and observation equipment.

List of Doctor Yellow trains past and present

For Tōkaidō and Sanyō Shinkansen

* Non-powered track recording cars (Yellow with blue stripe):
** 921-1: Built in 1962 (initially numbered 4001), and retired in 1980.
** 921-2: Converted in 1964 from former MaRoNeFu 29-11 sleeping car, and retired in 1976.
* 0 series type (Yellow with blue stripe):
** 922-0 (Set T1): 4-car set converted in 1964 from the prototype set ( class 1000 Set B) built in 1961, and retired in 1976.
** 922-10 (Set T2): 7-car set owned by JR Central. Built in 1974 and retired in 2001.
** 922-20 (Set T3): 7-car set owned by JR West. Built in 1979 and retired in 2005.
* 700 series type (Yellow with blue stripe):
** 923 (Set T4): 7-car set owned by JR Central. Delivered in 2000. Retired on 29 January 2025.
** 923-3000 (Set T5): 7-car set owned by JR West. Delivered in 2005. To be retired in 2027.

File:922 T2 Gifu-Hashima 19981011.jpg, JR Central Class 922 set T2, October 1998
File:Doctor-yellow.jpg, JR West Class 922 set T3, October 2004
File:923-0 T4 20130428.jpg, JR Central Class 923 set T4, April 2013
File:923 shinkansen T5 20080728.jpg, JR West Class 923 set T5, July 2008

For Tōhoku, Jōetsu, Hokuriku, Hokkaido, Yamagata, and Akita Shinkansen

* 200 series type (Yellow with green stripe):
** 925/0 (Set S1): 7-car set owned by JR East. Delivered in 1979 and retired in 2001.
** 925/10 (Set S2): 7-car set owned by JR East. Converted from former Class 962 test train in 1982 and retired in 2002.
* E3 series type (White with red stripe)
** E926 (Set S51): "East i" 6-car set owned by JR East. Delivered in August 2001.

File:925 sendai untensyo.jpg, Class 925 set S1, 1987
File:925-10 S2 Takasaki 20020925.jpg, Class 925-10 set S2, September 2002
File:TypeE926.jpg, E926 East i train, August 2020

Interior (Class 923)

Source:

File:Dr.yellow1号車.JPG, Interior of car number 1 used to inspect signalling, communications and power
File:Dr.yellow2号車.JPG, Interior of car number 2 used to measure electricity
File:Dr.yellow3号車.jpg, Observation window in car number 3
File:Dr.yellow5号車.JPG, Seats in car number 5
File:Dr.yellow6号車.JPG, A meeting table in car number 6

Retirement from JR Central Services

On January 29, 2025, the T4 set Doctor Yellow departed from Tokyo Station bound for Hakata Station for its final run on the Tokaido Shinkansen before its retirement, and for this special occasion, "ありがとうT4"(Thank You T4) was decorated on its windows. After Doctor Yellow's retirement, JR Central plans to use N700S Series units equipped with inspection tools to patrol its tracks.

Preserved examples

Currently, two examples of the Doctor Yellow units have been preserved:

* 922-26 (ex-set T3, built 1979 by Hitachi) at SCMaglev and Railway Park, Nagoya, since March 2011 to be moved to a tourist facility in Hakusan, Ishikawa Prefecture sometime after May 2025
* T4 (debuted in 2001) at SCMaglev and Railway Park, Nagoya

See also

* Comprehensive Inspection Train, used to evaluate the condition of the China Railway High-speed network.
*New Measurement Train, the British equivalent of Doctor Yellow, used to assess the condition of track
* TGV Iris 320, the French counterpart of Doctor Yellow, used to monitor the condition of the French tracks (mainly the high-speed railways LGV) used by high-speed trains, as well as High Speed 1 in the United Kingdom.

References

External links

{{Shinkansen

2025 disestablishments in Japan
Shinkansen train series
Non-passenger multiple units
Track recording trains