Quote:
Originally Posted by Nouvellecosse
What I want to know is how all these double tracked lines manage to have 24 hr service. For years I've been hearing that it's only possible in places like NYC that have additional tracks since that makes it possible for overnight maintenance work to happen by shutting down some tracks and not others.
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In Chicago, the majority of the 24/7 red and blue lines are only twin-tracked (the Northside red line is quad-tracked for roughly 7.5 miles, but most of the stations there only have center median platforms, so the outbound express tracks can't even access the platforms anyway).
To perform routine track maintenance, the CTA periodically closes roughly 1 - 2 mile-long sections of one side of the twin-tracks at a time in the middle of the night, and then runs two-way single track ops over that section. Obviously not ideal for wait and travel times when in effect, but I guess the CTA thinks it's worth it to keep the lines running 24/7.