The 9 was only removed becuase the ridership patters on the north end of broadway changed, to the point where the 9 was no longer effective. the IRT began to suffer from passenger boarding at a 1 only stop and wanting a 9 only stop or vice versa. Basicly 168th was getting a little crowed and thats not good for a station 100 feet down.
The J and Z's traffic is mostly peak direction and transfer points. The J/Z are an effective set up, which is why we still have the Z. It worked in the past, the line had skip stop service from 1959 to 1977 when service past Queens Blvd was cut. It was put back the day the Archer line opened.
yes it only runs for an hour, but it's giveing hundrids of people in that hour a quicker ride (acutally it's much more than one hour. Z trains normaly put in from ENY, run reverse peak local to the terminal, then run skipstop, then deadhead back). the average train holds a good 2-3 thousand people.
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