Hey there,

I've stumbled across some discussions in the past regarding modification in the vanilla bot pathfinding. Example, to make the bots do their job without leaving the logistic network, even if for that it wouldn't follow a straight line.

One example of such discussion is the following:
https://www.reddit.com/r/factorio/comments/6lta82/mod_request_limiting_bot_pathing_to_within/

In all occurrences of the discussion that I've stumbled upon, that idea has been turned down mainly because pathfinding is expensive, and would drop UPS significantly. And that does make sense, pathfinding is expensive, and the devs solution for bots to make only straight line paths, which is cheap to calculate, also makes sense.

Now for the question: How does Transport Drones not dramatically reduce the game UPS?

The question is more a curiosity and from a mod development perspective. I hope I didn't bore you too much with it.
Thanks for the great mod!

The main reason is that they only walk on the specific road tiles and don't collide with any entities.

This reduces the number of nodes available to check, constraining the pathfinding, so there is a smaller search space.
And then doing the collision check is orders of magnitude cheaper by not doing any entity lookups.

Oh cool, awesome.

Thanks for the reply :D

If the UPS problem is solved with the exclusive road, would it be possible to use the vanilla logistic system (bots, roboports, logistic chests, etc...) but change the bots behavior to be same as in the mod?

Say, if we change the logistic network reach to, instead of a range around the roboport, to be the road itself (similar to what this mod does: https://mods.factorio.com/mod/Robot_Zone). The road would remain exclusive for the bots. And then change the bots to be ground based, as in the mod, and to be able to move only inside the road, which happens to be the logistic network zone itself.

Would that be something possible/feasible?

A mod can't change any of the behavior of the logistic robots.

Oh okay, I didn't know that.