Can you be more specific about the objective of your project? Achieved speeds in the NYC subway are somewhat ambiguous, considering the fact that every operator has a different style of operation. No two trains on the same line traveling in the same direction are going to follow the exact same speed profile. Individual car classes within the system have different performance characteristics, and individual trains within a car class may perform differently based on the presence of dead motors or other defects. The general rule is that if you have a green signal ahead of you, you can keep the throttle @ 100%. The majority of curves now have timer control to automatically enforce curve limits, but again, each operator is going to approach the timers differently, some faster than others, depending on experience and level of comfort navigating that specific section of track. Additionally the state of timed sections is always in a state of change. Signal department is apt to install timers along a section of track that did not used to have them at any time. Case in point: the Rockaway bound approach into Howard Beach - JFK used to be un-timed, and trains could reach 40 mph before entering the station and taking a brake application. But within the last year, signal dept. installed a 20 mph grade timer on that approach, which slowed trains down significantly. Additionally, during the fall leaf season, several sections of out-door track have speed restrictions imposed to combat slip-and-slide conditions created by falling leaves. Finally, the presence of track work slows down trains through the area where work is occurring.
So again, if you can be specific on what you're trying to research and for what purpose, that would help us tailor our responses to your inquiry.