As somebody formerly involved with environmental analysis, I see the current change in emphasis from traffic operation to VMT as another faith-based thing, subject to very simple gaming. And the results won't be pretty.

Traditionally, near-road air quality has been tied to congestion and traffic volume, at points near "sensitive receptors". Good old-fashioned Level of Service provides a good screening tool for how much effect on local air quality will occur for a given project. LOS is now deprecated however; Vehicle Miles Traveled is the golden number. Adding capacity automagically produces more VMT because if you add capacity more people will drive. While that does seem to happen, it's not instant, and its effect on air quality is more regional and (for GHGs) global than local. For local impact screening, you still need to know how bad the traffic will be Right Here, and need a practical screening method (see LOS) to decide whether or not a lot of money needs to be spent on gathering data and running models. Funny thing: EPA has a procedure to follow that prescribes exactly that, with screening levels at certain LOS, traffic volumes, and truck volumes. BUT: because VMT is now the gold ticket, it's hard to get LOS from traffic studies. Go figure.

VMT can easily be gamed by limiting capacity and increasing congestion; in the limit, infinite congestion produces zero mph and therefore zero VMT. So road diets are popular in an effort to reduce VMT with no regard to traffic congestion and its very real effects on health and local economies. PSR can also be gamed - UP has done it in the past (and still does) without "knowing it" - simply eliminate on-line service for anything other than full trainloads. Raise the prices for carload and small-block service to the point where it's financially stupid to use a train. Once the traffic volume drops, it's easy to run the remaining trains at speed long distances.

Will it make more money? Probably, it will, in the short term. The Wall Streeters who only care about more profit, higher dividend, and higher stock price in the next quarter will love it. Once the "fat" has been cut along with enough muscle to see bone, though, it's hard to grow the business, and eventually that has to be done since just reducing cost can go only so far. CP and CN both found that out, and are now making capital investments again instead of just pulling up yards and selling the land; their stock prices while still good are no longer considered Growth candidates - more like Value and possibly just income. CSX probably will get there, too. The wheel turns...