40d:Traffic

Once a settlement begins to grow in size traffic may become an issue. Movement in narrow hallways are slowed by dwarfs moving past each other and vegetation will tend to die in outdoor areas with high traffic, eventually exposing bare soil.

Some traffic problems can be prevented by good fortress design, such as making hallway which are likely to be high use double width and placing stockpiles close to relevant workshops. Other difficulties may be reduced by setting traffic areas.

Setting Traffic Areas

The do combination sets traffic areas, which are used to manipulate the movements of dwarves. Traffic areas can be designated as high, normal, low or restricted. When walking from one point to another, dwarves consider these designations in finding the shortest path. High level traffic costs the pathfinding AI 1 point per square, normal (the default, and unmarked) costs 2 points per square, low costs 5, and restricted costs 25. You can change these values in init.txt.

• It is often a good idea to set any water source in a biome with seasonal freezing to restricted so your dwarves will be less likely to be caught on it when it melts.
• Some dwarves get disturbed if they walk through a butcher's shop and see an animal being slaughtered, so you may with to designate as restricted the shop.
• If an area occasionally gets flooded, or is dangerous for some reason, routing dwarves around it could be lifesaving.
• Setting high traffic areas along roads outdoors prevents vegetation from being needlessly trampelled.

Setting Restricted does not forbid a dwarf from traveling over those squares, but rather makes them willing to walk around them – for the normal cost table, 12.5 times further, or up to 25 times longer if there is an alternative high-traffic path. If you have an area that absolutely must not be stepped on by dwarves, consider walls.