A gantry (a.k.a. sign holder or road sign holder or sign structure or road sign structure) is a traffic sign assembly in which signs are mounted on an overhead support, or railway signals supported.
Gantries are usually built on high-traffic roads or routes with several lanes, where signs posted on the side of the highway would be hard to see for drivers. Gantries may be cantilevered or one sided on the left, right and center (sometimes referred to as a half-gantry or Butterfly gantry), or they may be bridges with poles on each side. Similar gantries are used in railway signalling on multi-track lines.