Editing Shinkansen (section)

=== Speed increases ===
====Tōhoku Shinkansen====
[[E5 Series Shinkansen|E5 series]] trains, capable of up to {{convert|320|km/h|mph|abbr=on|round=5}}, initially limited to {{convert|300|km/h|mph|0|abbr=on}}, were introduced on the [[Tōhoku Shinkansen]] in March 2011. Operation at the maximum speed of {{convert|320|km/h|mph|abbr=on|round=5}} between {{STN|Utsunomiya|x}} and {{STN|Morioka|x}} on this route commenced on 16 March 2013. It reduced the journey time to around 3 hours for trains from Tokyo to Shin-Aomori, a distance of {{convert|674|km|mi|abbr=on}}.

Extensive trials using the [[Fastech 360]] test trains have shown that operation at {{convert|360|km/h|mph|0|abbr=on}} is not feasible because of problems of [[noise pollution]] (particularly [[Piston effect#Tunnel Boom|tunnel boom]]), overhead wire wear, and braking distances. On 30 October 2012, JR East announced that it was pursuing research and development to increase speeds to {{convert|360|km/h|mph|0|abbr=on}} on the Tohoku Shinkansen by 2020.<ref name="jreast20121030">{{cite web|url=http://www.jreast.co.jp/press/2012/20121013.pdf |script-title=ja:グループ経営構想V |trans-title=Group Business Vision V |date=30 October 2012 |publisher=East Japan Railway Company |location=Japan |page=5 |language=ja |archive-url=https://web.archive.org/web/20121202011722/http://www.jreast.co.jp/press/2012/20121013.pdf |archive-date=2 December 2012 |access-date=17 November 2012 }}</ref> The [[ALFA-X]] is undergoing testing.

====Hokkaido Shinkansen====
Upon commencement of services in 2016, the maximum speed on the approximately {{convert|82|km|mi|abbr=on}} [[dual gauge]] section of the [[Hokkaido Shinkansen]] (including through the [[Seikan Tunnel]]) was {{convert|140|km/h|mph|round=5|abbr=on}}, which was increased to {{convert|160|km/h|mph|round=5|abbr=on}} by March 2019.<ref name="saves3mins">{{Cite web |date=31 March 2021 |title=Seikan tunnel Shinkansen speed-up saves 3 min |url=https://www.railwaygazette.com/high-speed/seikan-tunnel-shinkansen-speed-up-saves-3-min/58804.article |url-access=subscription |url-status=live |archive-url=https://web.archive.org/web/20210919081124/https://www.railwaygazette.com/high-speed/seikan-tunnel-shinkansen-speed-up-saves-3-min/58804.article |archive-date=19 September 2021 |access-date=5 March 2022 |website=Railway Gazette International}}</ref> There are approximately 50 freight trains using the dual gauge section each day, so limiting the travel of such trains to times outside of Shinkansen services is not an option. Because of this and other weather-related factors cited by JR East and JR Hokkaido, the fastest journey time between Tokyo and Shin-Hakodate-Hokuto is 3 hours, 57 minutes.

During the 2020-21 New Year Holiday period, certain Shinkansen services were operated at {{convert|210|km/h|mph|round=5|abbr=on}} on the dual gauge section and was proposed again for the [[Golden Week (Japan)|Golden Week]] Holiday period from 3–6 May 2021, due to fewer freight trains operating.<ref name="saves3mins" />
 
To achieve the full benefit of Shinkansen trains travelling on the dual gauge section at {{convert|260|km/h|mph|round=5|abbr=on}} (the maximum speed proposed through the tunnel), alternatives are being considered, such as a system to automatically slow Shinkansen trains to {{convert|200|km/h|mph|round=5|abbr=on}} when passing narrow-gauge trains, and/or loading freight trains onto special "[[Train on Train]]" standard-gauge trains (akin to a covered piggyback flatcar train) built to withstand the [[shock wave]] of oncoming Shinkansen trains traveling at full speed. This would enable a travel time from Tokyo to Shin-Hakodate-Hokuto of 3 hours and 45 minutes, a saving of 12 minutes.