Arlington wrote:Sorry if this has been asked, but neither the first 8 pages here or the MTA page say what the practical upside is when completed. Mostly just 100-year replacement with a bit of reliability in temp extremes and a bit of capacity due to power upgrades?
Well, it's just the cat, not the supply, that this project is about. CDOT's done quite a bit of outright power upgrades and power reliability upgrades to the source separately during the decade-long duration of this project. And they used the track outages during this project to replace more than a dozen undergrade bridges in the project area, refinish a bunch of overgrade span abutments and decks, and renovate some station platforms while the temp bridge plates were out in force. There was a lot of extracurricular going on in the coattails from this project that weren't directly part of the project. Definitely much more where that came from still needs to be done, but they threw a kitchen's sink worth of other SGR work between the margins and got their money's worth out of the ground time the track outages afforded their maint crews. The aggregate improvements go a lot further than just new overhead.
In addition to old components being old and shot, the switch to constant-tension cat is a big deal for reliability. Too many heat-related speed restrictions and brownouts with wire sag during summer, too many downed wires during winter. Too many intermittent track outages on any given day because a wire problem needed to be tended to. It was a very real and everpresent OTP drag for a line with such incredible traffic densities. And it would've prevented them from ever increasing train capacity making this new supplemental M8 purchase to run 10-car trains on the Stamford locals and New Haven expresses, because every extra pantograph per consist touching that bouncy old wire would've exacerbated the brownout problem and effectively imposed a cap on consist length that got shorter and shorter during summer heat and winter deep freeze. No matter how robust the juice was at the source, those +60-94 additional cars were never possible without full cat renewal.
On other parts of the NEC we mainly hear about constant-tension upgrades being coached in terms of Amtrak speeds
and reliability therein. This isn't going to make Amtrak go faster on the New Haven Line because traffic density on all 4 tracks in the limiter for Amtrak on the New Haven Line...but pound-for-pound C-T matters more here than in 150 MPH territory down in the Jersey swamp by keeping everything in that incredible traffic density moving more reliably with MUCH lower daily potential for wire-related speedos. We've already seen the positive effects with each new segment that's completed.