Doctor Yellow (ドクターイエロー) 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. In build and appearance, they are very similar to production, passenger carrying Shinkansen trains, and line inspection is carried out at full line speed (i.e. up to 270 km/h or 168 mph on the Tōkaidō Shinkansen).