The Texas Transportation Institute's Jerry Ullman talks about the state of the art in work zone safety in the US. Work zones are places where, perhaps more than anywhere else on the road network, mobility and safety are strongly linked. Historically, field crews and contractors wanted vehicles in work zones to be moving as slowly as possible, assuming that made conditions the safest for work crews. We are though starting to see a shift in such thinking with the realisation that excessive delays or slow-down