Signing and Pavement Marking Principles to Optimize Safety of Multilane Roundabouts

Mark Johnson

Principal Engineer
MTJ Roundabout Engineering

Mark Johnson is Principal Engineer for MTJ Roundabout Engineering. Mark founded MTJ in 2005, after 12 years of public- and private-sector transportation engineering positions, including 4 years for the City of Loveland, Colorado, and 4 years at the Wisconsin DOT where he was a key contributor to WisDOT’s roundabout program.
Mark has published papers on roundabout design and application issues and is a co-author of the 2010 FHWA Roundabout Guide Design section. Mark is an authorized FHWA Peer-to-Peer Roundabout Reviewer, an active member of the TRB Roundabout Committee, and Vice Chair of the ITE Roundabout Committee.

Conventional signalized intersections that have been replaced by multi-lane roundabouts have experienced a substantial reduction in both injury and fatal crashes. However, some have experienced a significant increase in PDO crashes. This has caused some jurisdictions to question the suitability of multi-lane roundabouts despite their benefit of reduced injury and fatal crashes. The question arises as to why some U.S. multi-lane roundabouts have substantially higher numbers of PDO crashes while other outwardly similar roundabouts do not. This presentation examines the hypothesis that the cause of the higher numbers of PDO crashes at some U.S. multi-lane roundabouts is driver confusion and information overload, arising from a combination of poor signing and pavement marking designs. We will review research and explore the best practice for roundabout signing and pavement marking using established traffic engineering principles and discusses aspects of the 2009 MUTCD that may contradict these principles. The paper highlights case studies of poorly performing U.S. multi-lane roundabouts, where the revised signing and pavement markings achieved 37%-80% reduction in PDO accidents. (from TRB/TRR published paper 2019)

Learn roundabout signing and marking design techniques that simplify decision-making and provide clear, concise information as to the correct way to drive the roundabout. Target audience: Traffic engineers and policy makers involved with implementation of roundabouts.

It is important to discuss updating the MUTCD signing and marking methodology for roundabouts, based on the application of proven human factors/signing and marking principles to reduce driver confusion