^ THere's all kinds of new crossovers, control points, & signals (including ones that have been obsoleted by PTC/Cab Signals), but I wonder how much they've actually been straightened? They've clearly benefitted from new & better drainage, new ties, and clean ballast (and way less scrub and trash trackside). (if we get too deep into CR, I'll move this to the "GLX impact on CR" thread that hasn't seen much action since the initial disruptions, Phase 1 bridge and trackside work, and the announcement of single-tracking and weekend bustitution)
The ROW geometry is exactly the same as before. So it's just the cleanroomed state-of-repair. The corridor hasn't been substantially renovated since 1979 when the most recent signal system was installed and the Somerville Jct.-Lowell trackbed was undercut to swap the Plate F freight clearance route here (replacing the Fitchburg Line + Fitchburg Cutoff when the Cutoff was retired for the Red Line Extension). So the layout of control points was from a different era, and most else was in a state of in-situ maintenance stasis sans any upgrading. Up until the earliest pre-prep work for PTC the line annoyingly still retained an asynchronous south-of-Wilmington speed limit of 70 MPH one direction vs. 60 in the other. It's all evened up to standard-spec Class 4/79 MPH now (individual speed zones below the max will vary by geometry, but at least they're the same in either direction now).
Optics are pretty much just observational bias, as older-but-100%-state-of-repair won't run any different but you've obviously got some nice whiter ballast spread around and no weeds poking through to goose pure cosmetics. The one thing that is different is that with cab signals in effect there are no longer any signal lights on the ROW except at the automatic switches & crossovers...which reduces the amount of field hardware and does superficially make the ROW look cleaner because it's minus a few signal heads that used to be there.
The first proof of any performance benefit will be if the new fiber-optic signal plant installed throughout the co-mingled GLX area and some degree north of there allows them to target the West Medford grade crossing speed restriction. High St. has no traffic signals near the crossing and retains a staffed crossing tender, imposing a painful 30 MPH restriction on thru
Downeasters and Haverhill-via-Wildcat expresses that skip West Med. Higher-tech traffic management has long been desired here, but the most oft-cited excuse (caveat: could very well be Joe Pesaturo B.S.) is that there was no nearby fiber plant for wiring up queue-dump signals timed to train passage. That may now be fully in-reach as result of all the inbound signal plant renewal. If they were able to install quadrant gates for stiffest protection around pedestrian darters (roadway has plastic-peg center dividers on both High & Canal, so is safe enough from vehicle gate-evaders), add a traffic light cycle for Harvard/Playstead abutting the crossing, and had the signal train-bombed for queue dumps the speed restriction could probably ease up to 60 MPH. We shall see the next time Medford has a townie bitch session about the crossings whether the "no fiber" excuse gets replaced by something else or if all parties are truly willing to get it done now. That's about the only coming attraction you could possibly direct-attribute to all this GLX-outflow work on the CR side.
Other than that, being regular old nonstop running track through the project area the other ancillary benefits are mainly "unsexy" related to refreshed state-of-repair and mildly simpler dispatching rather than anything that will show itself as 1 extra train or 1 minute in schedule savings.