Lane-use signals within the tolling industry are not as standardized in appearance and function as other equipment and devices used along or within the toll lane, such as the ITS, ACM, and loop detector. However, the simplicity and clarity of the message these devices are intended to display allows variation in design that is expected to result in minimal user confusion.
Conventional lane-use signals are specially fabricated overhead displays/signals that permit or prohibit the use of specific lanes. The two types of lane-use signals used most often by toll agencies are distinguished by their shapes and symbols. The rectangular fabricated signs typically display either an arrow or an ‘X’, using green and red colors, respectively. A variation to this scheme is shown in Exhibit 3.6, where a third state, flashing concentric yellow circles, is used when the lane is operated as a dedicated ETC lane. The other type of lane-use signal deployed above conventional plaza lanes is the traditional signal heads similar to those used at signalized intersections on arterials, with the signal heads positioned in a horizontal alignment.
From the survey responses, approximately 60% of toll agencies use lane-use signals consisting of traditional signal heads positioned horizontally. Sizes of the two primary lane use signals deployed today vary, with lane-use signal display panels ranging between 14 and 42 inches high, and signal heads ranging from 8 to 12 inch diameter are predominantly used. Although square display panel configurations are most common, rectangular displays are also being used by some agencies.
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