"What's the obsession with Union Square? The Gap Fillers? Union Square is not the cause of bottlenecking on Lexington Ave."
I don't have an obsession with Union Square. It just happens to be a potential bottleneck, and also a place that's convenient for me to observe.
I have never claimed that Union Square is the limiting bottleneck for the Lex. All I said was that, because of the signaling at Union Square, and the frequency of random delaying events, I don't believe more than 28 tph can get through Union Square southbound.
I acknowledge that there may be other more serious bottlenecks. In fact, since the SAS SDEIS says that 29 tph get fed into the system in the morning rush, but only 25 tph make it through GCT, there appears to be a more serious bottleneck north of Union Square.
Perhaps if I had done the same type of observations at GCT or 59th in the AM rush, I would have been able to make a case for a lower maximum number. But I didn't and I haven't.
PS. I do suspect that there is no other station on the 4/5 where it appears that every T/O requires at least 80 seconds to get into the station after the previous train has departed (Stephen's theoretical number for the current signals is 76). GCT, 59th, and 86th probably have lower figures for this parameter, but higher dwell times.