Through-service wasn't provided up to Nijo Station, the former west-end station on the Tozai Line, and it is said that the reason generally pertained to relationships with Keihan Electric Railway about the usage rates of train cars.
かつての東西線の最西駅である二条駅まで直通しなかったのは、京阪電気鉄道との車両使用料の関係が大きいとされる。