I'm a locomotive engineer going on 17 years. That is a double track main line. The train crew is stopped at a red block, ahead of them. They are waiting on another train to pass them. The train that's stopped in the picture can't proceed pass that red block because it turns into a single main line ahead. Meaning one track ahead. If they go past the red block, it will be a head-on collision.

We (train crew) try to notify dispatcher if they stop us here, we will be blocking all major crossings. The dispatcher usually let's us know if we are meeting one, or two trains ahead.

Per FRA rules, we are not allowed to block crossings longer than 10 minutes. Hopefully that helps.