Doctor Yellow Class 923 Shinkansen Bullet Train poster print.
Doctor Yellow is the nickname for the high-speed test trains that are used on the Japanese Shinkansen (“Bullet Train”) dedicated express passenger train routes. The trains have special equipment on board to monitor the condition of the track and overhead wire, including special instrumented bogies and observation blisters.
The “Doctor” part of the name is from their test and diagnostic function, and the “Yellow” part comes from the bright yellow colour they are all painted. Some have a blue waistline stripe, some a green one.