The more travelling I've done, the more I seem to appreciate NYC's existing subway system. Las Vegas, for example, has one hell of a useless monorail that can't even be called mass transportation.
So a lot of people have bemoaned the loss of a third track at 2 Avenue and 72 Street and the fact that pretty much all new subway construction will be double-tracked due to cost considerations. But after looking through track maps of different metros in the US and abroad, I've come to the conclusion that anything more has always been the exception and not the rule. Far more metro systems around the world are predominantly double-tracked, and most lack the luxury of extra tracks to orchestrate merging or redundant tracks for reroutes like the NYC subway does. And more likely than not, where a metro features interlining, the junctions are exactly like that at the 2 Avenue 72 Street station being built now.
Here are links to track maps of various metros for reference:
- Bay Area Rapid Transit (BART)
I must say that after my stay in San Francisco last month, the BART is very fast (even on crossover switches). The stations are spaced much farther apart outside the city (about a mile to 2 miles), and within the city the stations are about as far apart as those on the 2 Avenue line. The noise level is much louder though, and the entire system sounds like the Lexington Avenue line's express tracks at Canal Street right now. - Washington Metro
Trains here are also extremely fast, save for the longer station dwell times. There are only 2 triple-tracked stations in the entire system, and one of them (National Airport) can't be used for turning trains now that two switches have been removed from service; the other one is for short-turning trains and/or yard access. - Boston Metro
I can't say too much about the Boston Metro since I've only taken it between two stations to transfer between two Amtrak stations, but the ride was fairly quick. A look at the track map shows that while the Boston Metro is double-tracked for the most part, it has some triple-tracked sections (designed similarly to those in the BART), and makes use of more tracks at junction stations to hold merging trains. - Los Angeles Metro
I'll be visiting this city some time next year to see what it's like. - Chicago 'L'
I'll be visiting this city some time next year to see what it's like. - I've got nothing on the Philadelphia subway system yet, though its Broad Street line is said to be quadruple-tracked for a respectable length, spanning 15 stations.