Looking at https://stackoverflow.com/questions/7829097/android-accelerometer-accuracy-inertial-navigation https://stackoverflow.com/questions/7829097/android-ac

Looking at https://stackoverflow.com/questions/7829097/android-accelerometer-accuracy-inertial-navigation https://stackoverflow.com/questions/7829097/android-accelero... it seems that this could be doable - generally it looks like these devices are too noisy for straightforward inertial navigation, but constraining the problem to how far along your train is in a tunnel with occasional wifi is much more possible.