It affects speeds a lot, but if you turn on Google Terrain View you can see that it's nearly all geography-induced with few viable options for straightening. It's meandering around some very high cliffs, and there's no way you're plowing some Hoosac Tunnel-equivalent through Grafton & Union Hills plus the drainage region for Lake Quinsigamond. EMU's should be able to recover speed a smidge better coming off the curves, but that will always be a slow zone. The main thing planners will have to look at for any attempts at speeding things up is taking the segments that are already pretty straight and doing curve-easing on the much slighter curves that divide that territory up...such that you're running up the score a bit more where speeds are already good. The Worcester Hills are what they are, and Palmer to Grafton will always be subject to severe speed restrictions at the most unavoidable curves. But if the severe curves are few because the mere 'mildly annoying' ones out in Westborough and Ashland have been tweaked, you rack up meaningful improvements. That's where to focus the energy, if it can be done anywhere.This is really a commuter rail question, but what how much does the final stretch of the Worcester line — all the curves and loops — affect train speeds? And as a follow up, is there any chance at all that there would ever be a project within Worcester and Grafton to straighten out the line in order to achiever faster service to Boston?
I'll pour ice cold water on any notion of using the Pike median...which is just zombie residue from the wholly unbelievable NEC FUTURE I-84 tunnel-a-thon rejected alignment that borrowed segments of Pike median and the 1000% environmentally illegal Sudbury Acqueduct ROW to carve a hypothetical HSR line through the Worcester Hills. The highway grading is so much steeper than FRA-permissible RR grading it's physically impossible to do without dozens of miles of tunnel, and electric or no the constant changing of grades puts the trains in too much recovery time from ruined acceleration so the resulting performance would be awfully pedestrian in the real world even if it looks nice and straight in 2D. Pay no mind to it even as it shows up as umpteenth-Alternative alignments on official docs. The fact that the NEC FUTURE commission was so face-palmingly irresponsible as to not check its acid-fever alt. alignments against the laws of physics...then print those alignments as part of its report...means those zombie alignments will keep coming up again and again and again regardless of their impossibility. It was in a fed study, therefore it's going to get name-checked logic-be-damned in other studies years down the line. In the physical world, a passenger train bolted to the Pike is going to perform like ass on the constant substandard bunny-hop through the hills and cost an asstillion dollars in tunneling to ever hope to level out.