17479Q Site speed limit twenty mph Rigid Plastic (600x450mm) Safety Sign

A National Highways Safety Alert in 2025 (NHA359) highlighted the need to reduce potential driver confusion at construction sites by using only words rather than the numerical versions seen on public highways (as per TSRGD Fig.670 speed roundels). If you require alternative speeds please specify. This alert follows reports of incidents where drivers and vehicle automation systems misread works' speed limits, leading to sudden braking and hazardous situations in temporary traffic management zones.