Evaluation of Truncated Arrow per Lane Guide Signs

Some freeway and expressway interchanges contain an interior option lane in which traffic in that lane can choose to exit or remain on the route at the split. The 2009 Manual on Uniform Traffic Control Devices requires that either the Overhead Arrow per Lane or the diagrammatic guide sign designs be used for all multilane exits at major interchanges that have an optional exit lane that also carries the through route. However, some practitioners believe that it is cost-prohibitive and unnecessary to install Overhead Arrow per Lane guide signs at minor interchanges. Given the benefits of Overhead Arrow per Lane guide signs, a condensed version of an Overhead Arrow per Lane guide sign is needed for use where a full Overhead Arrow per Lane guide sign is not a reasonable option. A truncated version of the sign, which could be displayed on existing cantilever structures, would eliminate the expense of installing larger structures while still reaping the benefits of the Arrow per Lane sign concept. This study identified five signing alternatives for potential use at minor and intermediate interchanges with multilane exits and an option lane. Participants viewed videos of either Overhead Arrow per Lane guide signs or one of the four truncated alternatives. Participants were asked to indicate which lanes they could use to exit in some scenarios and which to use to proceed through in other scenarios. Participants typically understood the alternatives that provided information about both through and exiting traffic (80% comprehension), whereas alternatives that provided information about exiting traffic, with little to no information about through traffic, resulted in relatively low comprehension (38%).