[supercat]

One thing I was curious about: to what extent do any existing railway systems make use of an express/local system sharing one set of tracks (except for selected passing points) such that someone who wishes to travel 40 stops may travel 35 stops by express and then five by the local? In places where infrastructure could be adapted to support such a thing, it would seem that if it were well-coordinated it could significantly improve efficiency. I know Chicago has A and B trains, but what other such systems does anyone know about?

[glorgau]

I know Chicago has A and B trains,

Nope, they phased out the AB stops as a cost saving measure. I forget when, but here is a link to system maps. The last time they are shown is from the 1985 maps. A shame IMHO. The whole idea of transit is to make it more convenient than cars. All the extra stops add substantially to the total travel time during rush hours.

[steveegg]

I don't think that Metra runs like that (but don't quote me).