|maxheight = default|
|No specific legal height limit (no sign), default height rules apply here|
|Used on these elements|
|Status: in use|
|Tools for this tag|
The tag maxheight=default is used on highways where all of the following conditions are true:
- There isn't any traffic sign specifying a legal height limit for vehicles.
- The default country specific height rules for vehicles apply.
- A potential height restriction exist, for example the highway is a tunnel or is passing under a bridge or building. This is not a mandatory condition for using the tag validly, but it defines where the tag is useful.
If the first condition is not met, the specified limit should be tagged instead using the numeric values of maxheight=*. Otherwise, if the second condition is not met consider using maxheight=below_default or if clearance is known consider using maxheight:physical=*.
If only the third condition is not met maxheight=* should not be used at all because using maxheight=default here would blow up the database and even contradict the purpose of the tag. If users were required to add maxheight=default to nearly every highway they would likely do without checking that conditions are really met. If they did so this would obliterate the information of the tag.
How to map
For a tunnel, building passage or covered highway, maxheight=default should be set on the respective way. For a bridge the maxheight=default should be set on the way going under the bridge. Usually it is not required to split the way because this tag is not specifying a restriction, but that no restriction exist. In most cases this is valid for the full length of the existing way. If the way is long and there is potentially any object which might restrict height, but which has not been checked for height restiction yet, the way needs to be splitted because maxheight=default might not be true for the full legth of the way. If a highway passing under a bridge consists of two consecutive ways being connected near to the bridge you might consider tagging both ways with maxheight=default. This is useful because due to an position adjustment of the connection node the other way might become the way under the bridge.