Also - einfach erstmal nachlesen:

https://wiki.openstreetmap.org/wiki/Tag:highway%3Dconstruction

"This tag is used together with construction=* for any type of highway, including roads, tracks and paths, currently under construction and impassable by the traffic it is intended for. "

Also wenn Valhalla da meint trotzdem durchfahren zu können kann ich dem nicht helfen.