Japanese high-speed inspection train
The also known as the East-i, is a high-speed diagnostic train used on JR East's Shinkansen lines. Entering service in 2001, it is based on the E3 series and carries out line inspections at a maximum speed of . It operates on the Jōetsu Shinkansen, the Tōhoku Shinkansen as well as its two mini-shinkansen branch lines, the Yamagata Shinkansen and Akita Shinkansen; the train also operates on the Hokkaido Shinkansen, owned by JR Hokkaido, as well as sections of the Hokuriku Shinkansen owned by JR West. Similar types of diagnostic trains called Doctor Yellow operate on the Tokaido Shinkansen and San'yo Shinkansen.
Overview.
The Class E926 is a non-revenue earning diagnostic train designed to replace the aging Class 925 inspection train. The Class 925, based on the 200 series, had a lower top speed than newly-introduced trainsets at the time, such as the E3 series. Its loading gauge was also incompatible with the mini-shinkansen, which used narrower trains. At the time, the mini-shinkansen relied on KuMoYa 743 series inspection railcars. In response to these needs, the Class E926 was introduced in 2001, with the Class 925 withdrawn that same year. 
The i in East i stands for intelligent, integrated, and inspection. Since the routes and times of operation of the East i train are not publicly disclosed, it is considered lucky by railway enthusiasts when the viewer sees it.
Formation.
There are 7 East i series inspection train cars that were built. Cars 2 and 4 are equipped with a single arm pantograph. Prior to the scrapping of car E926-13 in 2015, when the 6-car train was being maintained, a spare track inspection car was inserted into an E2 series set.
References.
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