Concept

A dynamic display device would replace stop or yield signs for control of traffic at non-signalized intersections.  This device would function as a stop or yield sign in response to local traffic, time of day, weather, emergency, and/or other data provided through wireless connection to the Connected Vehicle network. 

Users

All drivers regardless of connectivity with the Connected Vehicle system would benefit from implementation of this concept. 

Benefits

Implementation of the this device would result in decreased travel time, less wear on vehicles and infrastructure, decreased fuel usage, and improved traffic control with corresponding positive impacts on mobility, the environment, and safety.  

Use scenario(s)

Primary usage of the proposed device would center on stop- or yield-controlled, non-signalized intersections where intersecting traffic varies widely with time of day or where other special traffic conditions exist (nearby emergency vehicle traffic, manufacturing shifts, event traffic, etc.).  More widespread usage, though beneficial, would need to be balanced with cost considerations.

Operation

Studies have found that overall trip time, fuel usage, vehicle wear, and air pollution decrease at intersections using yield signs as opposed to stop signs.  However, stop signs are often used in response to concerns over liability and implemented with worse case scenarios and nearby residents’ traffic calming concerns in mind.  Traffic engineers’ decisions as to what type of sign is needed are often based on traffic volume, sight distances, night time visibility, and other factors.  The proposed device is a dynamic display that would replace stop or yield signs at an intersection.  This device would communicate wirelessly with the Connected Vehicle system and potentially with Connected vehicles.  Data with regards to traffic, weather, emergency preemption, etc. available from the Connected Vehicle system would be used to determine what message is displayed by the dynamic display whether “Stop”, “Yield”, or another message (Figures 1 & 2).  Other messages might include emergency preemption or other special notifications.  A driver in a vehicle equipped for Connected Vehicle might also be warned of their approach to a hidden sign, or to one it’s apparent they haven’t recognized, by a flashing display or audible warning from the sign or via the in-vehicle interface.   Figure 1.  Dynamic Sign Operation During Periods of Increased Traffic or Special Conditions    Figure 2. Dynamic Sign Operation During Periods of Low Traffic

Communication Requirements

Wireless communications would be accomplished by DSRC, cellular, or other wireless methods.  DSRC would likely be required for communication between the dynamic sign and nearby vehicles.  Use of the device as a “repeater” node on a DSRC mesh network would provide an option for reliable, widespread, and inexpensive expansion of the Connected Vehicle communication system. 

Implementation

Implementation of the dynamic stop/yield signs would require the following: Development of a relatively low cost, energy efficient, dynamic display at least as visible as that of static signage.  The unit would be weatherproof and powered preferably through energy harvesting from solar or in-pavement sources.  The device would include a unique I.D. for registration with a known location or a built in GPS receiver to provide location and time data.  A wireless transceiver would be integral within the unit. Development of an algorithm that uses traffic, weather, and other data for determination of display mode is appropriate.  Development of a dataset that includes all data required for operation of the dynamic stop/yield algorithm. Replacement of existing stop or yield signs at suitable intersections.      Attachment(s): Figure 1. File -  “stop-yield-sign(1).jpg” Figure 2. File – “stop-yield-sign(2).jpg” Animated GIF of Figs. 1&2 -  “stop-yield-sign.gif”

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