Hallo Mark,
Thanks for your comment. We didn't try to exactly replicate TDP, but have some functionality that we felt was missing at that time. Glad you like it.
Re Cancel of a route: I noticed you cancelled the route "backwards", first clicking the end block then the start block. It was never intended to work that way (only start block then end block), but apparently it is possible to proceed that way. However, that leads to a situation that keeps fragments alive you can't get rid of.
We will correct this in the upcoming Release 3.9.
We have not yet implemented the capability to give permission to pass a red signal. It is not really necessary right now, as you always can set a route, or if the signal was cancelled but the route is not cancelled yet, you can clear the signal (undo the signal cancel) just by clicking on the signal symbol with the left mouse button.
The passing of a red signal will be an issue if you want to send a train to a track that is occupied where a route cannot be set because of that reason. We have not worked out the details how to maintain 2 or more trains on a single block, which you need to so also if you want to merge or split trains. Once we've done that, we will be able to merge and split (via scheduling), and the passing of a red signal will be an option along with possibly allowing a signaled secured route into an occupied block.
In the meantime, enjoy the game.
Your WebRailRoader
Detlef