The visuals are very nice, and I can see how these systems could lead to some interesting logic/sequencing puzzles, but the timer really worked against the game for me. The timer made the later puzzles actively frustrating e.g. the third stage required multiple quick actions, and a reset took you back to a quick and easy first stage.
Generally, you have to be a little too precise with where you're dragging, and the timer made that issue a bit worse. Here are some specific examples:
It wasn't very intuitive for me that you had to drag all the way to the target square to complete a route. I initially tried releasing the mouse one short because it visually looked like the road was connecting to the target building. It would have been nice if that had completed the route (unless it is ambiguous).
Dragging along a route, if you cut a corner that's off grid or invalid, you have to go back and re-do that movement. It would be really nice if the input areas around edges/invalid squares were a little more forgiving, and maybe if there was a little interpretation around corners.
I also found myself dragging to the end of the route and releasing my mouse past that space and off the grid, which reset the route. It would have been nice if that counted.
If you were going to remove the timer for a post-jam version of the game, those little things could still help improve the game feel.
I like the puzzle you have here (minus the timer). This really seems like something you could extend into a larger game with more mechanics and complexity, and it's a really good start.