SMART trains are FRA-compliant DMUs. They *can* run at the same time as freight trains, like the WES line near Portland OR but unlike the light rail DMUs that Sprinter (Oceanside-Escondido CA) uses. However, freight will most likely run at night or midday - outside commute times - as you state, simply because SMART will need all the sidings it has to run the passenger trains. If the line turns out to be popular, they might need to add sidings, or lengthen some into 2 main tracks for some distance, to make better schedules possible. As it stands, they spent all their money (and more) to turn 2 streaks of rust into a usable, though not great, passenger line. It ain't no BART and wasn't intended to be. Oh, and there's no freight service on the southern part of the line (south of Ignacio); freight traffic comes in from the east at about Hwy 37 and runs north to Windsor, slightly past the current end of the passenger zone at the Airport.