Specific service signs provide motorists with business identification information along freeway approaches to interchanges. The Manual on Uniform Traffic Control Devices limits the number of these signs along an interchange approach to four and the number of logo panels per sign to six, although there are continuing requests to increase the number of panels allowed per sign. The present research evaluated specific service signs with four, six, or nine panels per sign and with all logo-based panels or all text-based panels. Participants were asked to determine whether a particular business was present on a sign. Mean reaction times indicated that for nine-panel signs, younger drivers took approximately 2.2 s to determine correctly the presence of a business, while older drivers took approximately 2.9 s. In considering drivers of all ages, an increase from six to nine panels brings mean reaction times from 1.8 s to 2.5 s for text signs and from 1.9 s to 2.5 s for logo signs. In a second task, participants were given 2 s to view each sign before reporting the businesses present on the sign. Participants reported three to four businesses on average, regardless of the number of panels on the sign. Considering the generally accepted standard that eye glances away from the forward roadway for greater than 2 s are unsafe, the study concluded that the benefit of providing more service information is presumably not great enough to outweigh the risk of information overload and driver distraction.

Summary: Drivers' eye glance behavior was examined as they drove on a variety of roadways that varied in visual clutter and the presence or absence of advertising billboards. Eye glance behavior appeared to be more heavily influenced by the nature of the driving task than by the stimulus attributes along the roadside. The mean proportion of glances to the road ahead ranged between 0.80 and 0.87 across conditions. The lowest mean proportion of glances to the road ahead was seen in conditions of high visual clutter, which contained offpremise billboards. Under high levels of clutter, drivers directed more glances to the left and right side of the road than under conditions of low clutter. The longest mean glance durations away from the forward roadway were to the right side of the road (0.105 s) and not to billboards. Mean glances to billboards were 0.078 s and 0.087 s under low and high clutter environments, respectively. The results showed that level of visual clutter present in the highway environment affects how drivers glance at scenes. However, this did not appear to be at the expense of focusing on the forward roadway.

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%).

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As drivers continue to purchase electric vehicles, there is an increasing demand for electric vehicle charging stations and, consequently, signing for these stations. Previous research evaluated a sign which was recommended to the Manual on Uniform Traffic Control Devices (MUTCD) team for addition to the MUTCD; however there remained concerns that drivers’ perceptions of electric vehicle charging stations signs had not been adequately addressed. The present research focused on driver comprehension and perceived risk of electric shock in regard to two electric vehicle charging station signs. Members of the driving public completed a computer-based survey which consisted of open-ended questions, rating tasks, and ranking tasks. Drivers did not necessarily associate a risk of electric shock with electric vehicle charging stations. In fact, nearly 100 percent reported that they would feel comfortable using a public electric vehicle charging station. When asked specifically about the risk of electric shock, statistically significant differences in sign alternatives arose only in the risk of electric shock implied by the sign. Further, drivers perceived the risk of shock from using an electric vehicle charging station as lower than many commonly used items which contain an electric charge (e.g., toaster, hair dryer, and extension cord). Given that both alternatives were well comprehended, either sign is suitable for use.