I have a problem with dwarf pathing that I wonder if any of you have a solution to. I'm constructing a spike corridor intended on exposing trap avoid creatures to a series of retracting spike traps while causing non-trap avoid creatures to safely bypass the corridor. Here's the corridor under construction with the pathing enforcement hatch covers, doors, and pressure plates in place and functional.
The center corridor was eventually going to be filled with spike traps hooked up to a repeater. The pressure plates at each end are hooked up to the hatch cover and door next to each pressure plate. The two breaks in the walls near the middle of the three corridors are covered by hatch covers over a pit. They are intended on providing maintenance access to the dwarfs for corpse removal and such. When the repeater is running, the hatches are open denying access. And when the repeater is off, the hatches are closed, permitting access. In the image provided, the hatches are open.
Now for the problem I'm having. The dwarves get "stuck" in a loop with this construction. I ordered a channel to be dug for a grinder off to the right of the image. The miner that took the task was off to the left of the image. Here's what he did.
1. Approached the passage ways heading east until he reached the western pressure plate.
2. Upon hitting the pressure plate, both the door and hatch cover opened, denying access to the central corridor and granting access to the southern corridor.
3. Dwarf took the southern corridor and continued east.
4. Upon reaching the end of the corridor and taking the NE jog, the dwarf then turned NW until he hit the eastern pressure plate. When this happened, the door and hatch cover both opened, denying access to the central corridor and granting access to the northern corridor.
5. The dwarf then proceeded to take the northern corridor heading west until he exited it just west of the western pressure plate.
6. Finally, he headed east again until he hit the western pressure plate and the cycle repeated with the dwarf going around the entire circuit counter clock wise until I eventually had another dwarf pull the lever to close the two maintenance hatches. When that happened, the dwarf entered the central corridor, pathed west for a short bit, then pathed east and finally heading towards his original pathing goal.
Obviously, that pathing behavior means that my original plan isn't going to work. I've tried various combinations of designating high/normal/low/restricted traffic on the three corridors to no avail. If all else fails, my alternative plan is to have a relatively short spike corridor with protective pressure plates and hatches to keep the dwarves safe and a longer non-trapped corridor that they'll actually travel to get to their destination. But it isn't as guaranteed to prevent trap avoid creatures from taking the same longer but "safe" path.