Shiosai services operate over the Sōbu Main Line, stopping at the stations listed below. All 7 round trips are operated daily except for one inbound trip which is not operated on Saturdays and holidays. No services operate as "Local" all-stations services in any section; this characteristic is different from that of Wakashio ltd.exp.[1][2][3]
Shiosai services are operated using Kamakura-based 6-car E259 seriesEMU and Makuhari-based 10-car E257-500 series EMU formations. The E257-500 series formations have no Green (first class) cars.[5][2]
255 series 9-car EMUs (10 December 2005 – 15 March 2024)[4]
Formations
Trains are formed as shown below, with car 1 at the Tokyo end.[2]
9-car 255 series
Car No.
1
2
3
4
5
6
7
8
9
Numbering
KuHa 254
MoHa 254
MoHa 255
SaRo 255
SaHa 254
SaHa 255
MoHa 254
MoHa 255
KuHa 255
Accommodation
Reserved
Reserved
Reserved
Green
Reserved
Non-reserved
Non-reserved
Non-reserved
Non-reserved
5+5-car E257 series (No. 4 only)
Car No.
1
2
3
4
5
6
7
8
9
10
Numbering
KuHa E256-500
MoHa E257-1500
MoHa E256-500
MoHa E257-500
KuHa E257-500
KuHa E256-500
MoHa E257-1500
MoHa E256-500
MoHa E257-500
KuHa E257-500
Accommodation
Non-reserved
Non-reserved
Non-reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Non-reserved
Non-reserved
Past formations
183 series EMU on a Shiosai service, May 2005
Trains were originally formed of 9-car 183 series EMUs, including one Green car, or 6-car sets with no Green car,[6] but from December 1994, services were formed of 8-car 183 series sets with the Green car removed, as shown below.[7][8]
8-car 183 series
Car No.
1
2
3
4
5
6
7
8
Accommodation
Reserved
Reserved
Non-reserved
Non-reserved
Non-reserved
Non-reserved
Non-reserved
Non-reserved
History
165 series EMU on a special Inubō revival working in November 2002
The Shiosai service was introduced from 10 March 1975 following the completion of electrification of the Sōbu Main Line in October 1974, using 9-car 183 series EMUs, replacing five of the seven daily diesel-powered Inubō (犬吠) express services that operated between Shinjuku/Ryōgoku and Chōshi.[8]
From the start of the November 1982 timetable revision, further 183 series EMUs were drafted in, displaced from Toki limited express services following the opening of the Joetsu Shinkansen,[9] and the remaining Inubō express services were discontinued and absorbed into the Shiosai services, giving seven return workings daily.[8]
From the start of the revised timetable on 10 December 2005, 255 series 9-car EMUs were introduced on Shiosai services.[10] From the same date, services were made entirely no-smoking.[10]
From the start of the 14 March 2015 timetable revision, all Shiosai services started and terminated at Tokyo Station, with no services operating from Shinjuku.[11]
From the start of the 16 March 2024 timetable revision, E259 series 6-car EMUs used on Narita Express services are scheduled to also be used on Shiosai services for six return trips. Meanwhile, E257 series trains in 5-car formations will continue to be used for one return trip. As a result, 255 series sets will no longer operate on these services.[4]
^ abc"2023【ダイヤ改正日】 2024年3月16日（土） - JR東日本" [2023[Timetable revision date] Saturday, March 16, 2024 - JR East] (PDF) (in Japanese). JR East. 15 December 2023. Retrieved 22 December 2023.
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