On-pavement signing shows a curve sign or other pavement marking symbol (such as the speed limit) in advance of a curve or other problem location.
Use of wording or signing on the pavement surface is more dramatic than vertical signing, which can get lost in the clutter of a streetscape. However, on-pavement signing has not been widely used in Iowa to address lane departures.
One study evaluated the use of on-pavement signing consisting of the word SLOW with a curve arrow framed between two horizontal bars. The treatment was applied along two curves. Both mean and 85th percentile speeds were reduced by around 1 mph (Hallmark et al. 2012).
No information is available about the crash impacts of on-pavement marking legends.
More information is provided in this technical brief, On-Pavement Signing (PDF), which summarizes information about pavement marking legends relevant to Iowa.
Hallmark, Shauna, Neal Hawkins, and Omar Smadi. Evaluation of Low-Cost Treatments on Rural Two-Lane Curves. Center for Transportation Research and Education, Iowa State University, 2012.