Monday, April 6, 2015

JR East mobile app pinpoints your location on the Yamanote Line

At about the same time Japan Airlines released a revamped mobile app that was actually useful, so did JR East. Many train companies have their own apps, but I rarely install them because they are only good for navigation within that particular rail network. Yeah, they probably have station information, route maps, and the like, but do you really need an entire app for that?

The JR East app is set apart from other train operator's apps by determining your exact carriage on Yamanote Line trains based on the MAC addresses of the on-board wifi access points (APs). This is exactly how your phone gets a location when GPS is unavailable. (Moving mobile APs on trains can also be the source of erroneous location information when one of these gets mapped into a location database.)

As you can see in the above screenshot, I was riding in car 4, which was slightly more crowded than the surrounding few carriages. Car 4 had the temperature set milder (弱) but the interior temperature was not significantly different from the other carriages at a pleasant 19˚C.

One of the things that completely annoys me to no end is the scarcity of carriage information posters in JR stations. You know, the ones that show which cars are close to which exits at each station along the line. If you're lucky, you might walk the entire length of a platform designed to accommodate a 15-car train and find between zero to one of these important posters, whereas the subway operators place them every few 10s of meters.

This app can also show you the platform information for upcoming stations, so that if you're on a tight transfer, you can head towards the carriage closest to where you need to be.

Unfortunately, all these cool features are limited to the Yamanote Line. I imagine that will change because it's possible to do this with any train that has on-board wifi. It's of course only available in Japanese, but as the 2020 Olympics approach, expect an English (at least) localization.

The app's home screen is expectedly a bit cluttered, and it's difficult to know exactly where to go to access these features. To get to the features I described, access the 山手線トレインネット.


  1. So I did the very unscientific test of trying each patch and leaving it in the same place for a few hours. The datasim_patcher may actually save more battery (mode 99 on Moto G v2) but to say definitively would need more testing.

    They both showed solid green on the cellular battery bar the whole time, however there were periods with datasim_patcher where battery level was completely flat, while with the DocomoSimPatcher battery level was always slightly declining. As with everything else, YMMV

  2. Thanks for the tip!

    I've found both English and Japanese JR East apps on the iOS App Store. The English one's publish date is 20th March whereas the Japanese one's is yesterday. I'll try both and see but the details bit for the English one mentions carriage temperature so I might just stick with that one.

  3. Hello there.
    After many problems I finally managed to install everything on my cellphone (Xperia SP) but I still have problems with the network (always cutting down and reconnect, and down....) and I don't have any Internet access....
    I've bought a OCM mobile ONE of 70Mb/day.
    I had many problem just to root my phone but after I succeed everything went smoothly for the installation.
    Do you have any ideas how to fix things and to have my network and internet? I'm gonna be crazy if I can't use it for my 5 months stay in Japan...
    Thanks in advance.