Originally Posted by
moondog
In Shanghai, at least, urban rail trains can't really sell out tmk (they are treated like subways), but they are S-trains, and I notice the Badaling trains have G prefixes, which makes them seem more organized to me.
There are a few S trains in Beijing, including S2 - the slow train to Badaling - but these have 2-3 trips per day and are for all intents and purposes worthless to the average commuter.