On January 22nd, the five railway companies, Yokohama Minatomirai Railway, Tokyu Corporation, Tokyo Metro, Tobu Railway, and Seibu Railway, announced the outline about their new timetables for going-through service between Hanno Station on Seibu Ikebukuro Line or Shinrin-koen Station on Tobu Tojo Line, and Motomachi-chukagai Station on Yokohama Minatomirai Railway Line via Tokyo Metro Fukutoshin Line and Tokyu Toyoko Line.
According to the press releases and new timetables, it is an important point that those five lines have a different pattern of train service and most trains change the name of service at the border station between the companies. For example, In case of a limited express train on Toyoko Line going through Fukutoshin Line and Ikebukuro Line, the name of service changes to express on Fukutoshin Line at Shibuya Station and does to rapid express on Ikebukuro Line at Kotake-mukaihara Station.
On the weekdays, fourteen trains go through Fukutoshin Line from Toyoko Line an hour. Six local trains (as local trains on Fukutoshin Line), four express trains (as local trains on Fukutoshin Line), and four limited express trains (as express trains on Fukutoshin Line) serve. More specifically, two local trains terminate at Shinjuku-sanchome Station, four express trains and two local trains are bound for Wakoshi Station, two limited express trains and two local trains go toward Ikebukuro Line, and two limited express trains toward Tojo Line. In the morning and evening, the limited express trains and the commuter limited express trains go through Fukutoshin Line (as commuter express trains) and Ikebukuro Line (as rapid trains). The express trains do (as express trains toward Ikebukuro Line or commuter express trains toward Tojo Line). Also, some local trains from Senkawa Station toward Toyoko Line and terminated at Ikebukuro Station from Toyoko Line started to serve.
From here, I would like to write about my opinions. First is about the comparison to JR East Shonan-shinjuku Line, second is the pattern of the train service.
It takes 38 minutes by going-through train on Toyoko Line and Fukutoshin Line between Yokohama Station and Ikebukuro Station, which is three minutes longer than that of Shonan-shinjuku Line. However, the travel time of the going-through service train between Yokohama Station and Kawagoe Station is shorter. It takes 78 minutes without transfer. In case of travelling JR lines, it does more 12 minutes via Shonan Shinjuku Line and Saikyo Line with a transfer.
About the pattern on Ikebukuro Line, the fast trains from Fukutoshin Line serve as the rapid trains or semi express trains on Ikebukuro Line because the trains have to stop at Nerima Station. However, those from Toyoko Line does as the rapid express trains, which is the second-fastest service. I see that Tokyo Metro and Seibu may accept Tokyu's request to serve the fast and convenient service on Fukutoshin Line and Ikebukuro Line.
On the other hand, all trains from Fukutoshin Line stop at all stations on Tojo Line. In my opinion, it would be better that the express trains on Fukutoshin Line serve as the express trains or the rapid express trains on Tojo Line to be faster and to extend its service to Shinrin-koen Station. Because of a few train services toward Tojo Line, some local trains from Fukutoshin Line need to extend the service to Kawagoeshi Station. However, Tobu Railway has no plan to extend trains toward Fukutoshin Line and Toyoko Line to farther than Kawagoeshi Station because of long distance and no demand.
Some railfans who know the history of Japanese railway may be surprised at the going-through service between Toyoko Line and Ikebukuro Line. In 1950s and 1960s, Tokyu Corporation and Seibu Railway competed to develop tourist attractions in Hakone, Kanagawa Prefecture. Also, the sidetrack at Shinjuku-sanchome Station for returning the trains from Toyoko Line may remind some railfans of an old extension plan to Shinjuku Station of Toyoko Line.