they say it won't increase rail capacity downtown because the steel bridge is a huge chokepoint. The "Y" switch on the east side already causes delays (buses, cars, peds and trains all going through the one key link in the system), and they will add another one on the west side which will cause double the delays. Plus all the additional trains as well.
Last time I read any news on this issue Trimet was in talks with the RR (Steel Bridge owner), ODOT and PDOT about the possibilities of;
-making the MAX track lanes only for LRT, removing the only part of bus, auto and MAX mixed-traffic on the entire system.
-in the future making the entire upper deck MAX (and maybe bus) only with 4 lanes of tracks, and free up developable land where the current on and off ramps for autos exist.
-full upgrades to the bridge lift joints which are the most time reducing aspects to MAX crossings.
the actual switches on either side of the bridge are being worked on as part of the mall project which will help capacity (the east side already has full traffic light priority, and the west side will be brand new) as well as having a new route through downtown for the Green and Yellow lines, leaving more room for the Blue and Red lines to expand (this leaves only the traffic lights, 200 ft blocks and the Steel Bridge joints as capacity restrictions).