Active traffic management: comprehension, legibility, distance, and motorist behavior in response to selected variable speed limit and lane control signing /

Active traffic management (ATM) incorporates a collection of strategies allowing the dynamic management of recurrent and nonrecurrent congestion based on prevailing traffic conditions. These strategies help to increase peak capacity, smooth traffic flows, and enhance safety on busy major highways. This final report describes a series of experiments that developed and tested alternative signs focusing on lane control signs (LCS) and variable speed limit (VSL) signs and used the deployments in Minnesota and Washington as inputs to sign development. Laboratory and field studies determined both the comprehension of the ATM signs as well as their respective legibility distances. Two driving simulator studies helped determine how motorists responded to these signs in a simulated driving environment. Research results are discussed for the various studies, including legibility distances, driver behavior, speed selection, and visual clutter with respect to the used of the LCS and VSL signs.

Static speed limits are the norm across the world's roadway networks. However, advances in technology and increased applications in intelligent transportation systems (ITS) provide a mechanism for upgrading traditional speed limits into an active traffic management system. More specifically, variable speed limits (VSLs) can be used in high crash severity locations and in real-time congestion and weather events to increase traffic safety and operations. Much of the available literature on VSLs focuses upon crash prediction algorithms for VSLs, simulations, and effectiveness of real-world VSL implementations. One noticeable gap in the existing literature is related to driver compliance under varied configurations of alerting drivers of the variable speeds. An additional gap in literature is related to existence of a conceptual framework for identifying optimal corridors for potential VSL implementation. Within this thesis drivers' willingness to comply with VSLs was investigated via focus groups and static surveys during the experimental process. Connections are made between driver speed choice and type of speed limit condition including uniform speed vi limit (USL) versus VSL, overhead mount versus side mount, presence of an explanatory message, and the numerical speed limit value. An analysis of the survey results was completed to isolate critical factors in VSL compliance. Opinions and perspectives on VSLs are derived through the focus group sessions Lastly, a case study approach is presented in which a region is chosen, and implementation metrics are analyzed on the major roadway networks using a GIS platform to create a composite ranking system for potential optimal VSL corridors. The study aims to be used as a foundation to justify use of certain types of VSLs in addition to creating a conceptual framework for VSL implementation zone identification.