I realize they theoretically "can" hold more capacity, but I would suggest that they WON'T move more people per hour than the two dedicated traffic lanes do today.
according to the DOT, I90 express lanes move about 7,000 vehicles an hour at peak, including buses and carpools https://www.wsdot.wa.gov/North...
ST projects (and they usually offer VERY optimistic projections) that in 2030, the entire eastlink project will carry 50,000 riders/day. So, in 13 years, along the whole route, ST "projects" that the trains will "almost" carry the amount that cars carry today, for free.
http://www.soundtransit.org/ea... (bottom right rail has the projection)
but overall, yeah, they're a great boondoggle. tell me again why not just more buses,a nd keep the lanes available for carpools, buses, ambulances, etc?