# How can I tell if a 1x1 bridge is raised?

If I place a 1x1 bridge, and hook it up to a lever, how can I tell if that bridge is raised? If the lever is ON, will it always be raised (I dont think so, because I can hook it up while the lever is ON, thus flipping the bits, right?)

• A minor note, not really related to the question itself, but addressing an issue that may cause issues later which is revealed by the question. Flipping a lever does not flip the state of a bridge. It sets the state of the bridge to the state of the lever. So if you hook a bridge up to a lever that is already on, the first time you flip the lever nothing will happen. This can also cause issues if you are hooked up to something that sends open/close signals faster than the bridge/door/etc. can change state.
– Nick
Dec 10 '14 at 23:53
• @Nick Does that mean that if a bridge is only hooked up to one lever and it has been flipped at least once, then ON will always mean raised and OFF will always mean lowered? Dec 10 '14 at 23:55
• If you are very careful then yes. The wiki explains it more thouroughly at the page on levers. There is a delay in the change so if you pull the lever too fast several times in a row it won't change for all of the pulls and might end up in a different state. Also there are some other conditions that can prevent a bridge from changing state, such as very large monsters standing on them.
– Nick
Dec 11 '14 at 1:19

This is actually a problem for all bridges of length 1. The lever state cannot be relied upon to indicate the bridge state, especially if two or more levers (or other mechanisms) control the bridge. Here is the solution I have found.

There are two cases:

• In one case the bridge is submerged in liquid. If this is the case then the liquid will show instead of the bridge whenever the bridge is open (that is it can be passed because it is lowered). Conversely the bridge will show instead of the fluid when it is raised.

• In the other case where the bridge is on dry land you can determine the state of the bridge using meeting zones. Place a 1x1 zone on one of the tiles that the bridge occupies. If the bridge is lowered and dwarves can stand there then the zone will say that it has a tile usable as a meeting area. If the bridge is raised and behaving like a wall then the zone will have no tiles available as a meeting area. There are several other zone types that behave in the same way such as garbage dumps, pen/pasture, hospital and animal training.

Press b,d to build door. Hover the cursor over the bridge.

• If it says "Building present" - bridge is down (passable).

• If it says "Blocked" - bridge is raised.

• Way better solution than accepted answer! Nov 11 '18 at 6:33