Note: this post is marked archived as construction was completed.
The JR Shibuya station platform and track realignment of the Yamanote Inner Circle line takes place October 23~24 (unless bad weather postpones it to November 20~21). All Yamanote Inner Circle train service between Ikebukuro and Osaki stations is suspended all day, both days.
JR East posted multilingual information in English, Chinese, Korean (deleted after the construction was finished) that includes detour transfer guidance to non-JR lines during the line closure. The English wording is fuzzy because the exact distinctions between mag-strip commuter passes, Suica commuter passes and Suica IC transit fare are not always clear to the reader. It’s also important to understand detour transfer rules.
Tokyo area transit operators have special detour transfer rules to deal with transit situations when there is an unexpected stoppage and in-transit users suddenly need to use a different transit route from the normal one to reach their destination. Detour transfers have one rule for Suica or PASMO commuter passes, both mobile and plastic: do not use automatic transit gates during the detour portion of the route, go to a station agent window gate instead and use the reader. The station agent checks the validity of the commuter pass and waves you through, the NFC equivalent of visually inspecting printed tickets and passes. Regular non-commuter pass Suica, PASMO and other transit cards are outside of detour transfer rules and are charged normal IC transit fare.
For example, my normal commute route from JR Asagaya to Tokyu Ikegami has a line transfer point at Gotanda. A Gotanda transfer isn’t possible during the service suspension. Instead I plan to transfer at Shibuya to the Tokyu Toyoko line, ride to Jiyugaoka > transfer to Tokyu Ooimachi line > transfer at Hatanodai to Tokyu Ikegami line > exit at Ikegami.
In this case I make 2 automatic gate reads and 2 station agent window reads with my Apple Watch Suica commute pass: the JR Asagaya start point (automatic gate as always), leaving JR Shibuya (JR station agent window reader) transfer to Tokyu Toyoko line (Tokyu station agent window reader), Tokyu Ikegami (automatic gate as always).
This poster at the Tokyu Ikegami station clearly shows the ‘do not use automatic gates during detour rule,’ and which kinds of tickets can be used for detour transfers: Suica and PASMO commuter passes and all mag strip passes and tickets. For Apple Pay Suica and PASMO commuter passes, always use the station agent window reader on the detour portion and you’ll reach your final destination even with a long detour.