Vehicle to Pedestrian Connections

Connected Vehicle technology can be used to help prevent many types of traffic accidents, including those between vehicles and pedestrians.  UMTRI researchers are examining two methods for detecting pedestrians crossing the road. By detecting pedestrians in the road, and by using technology deployed as part of the Ann Arbor Connected Environment, some drivers will be able to receive warnings in their vehicle about pedestrians in the road ahead.  

Four “mid-block” (i.e., not at intersections) crosswalks along Plymouth Rd. in Ann Arbor, MI have been equipped with systems that can both detect pedestrians, and broadcast a “Pedestrian Safety Message” to approaching vehicles when there is a pedestrian crossing the road.   In this study, the detection of pedestrians can happen in two ways: through a phone application, or through the use of an overhead camera.   Pedestrians who report crossing at one of the equipped crosswalks regularly can download a cell phone application which uses the phone’s GPS to determine when the phone is in or near one of the target crosswalks.  When the application believes it is in a target area, it communicates with equipment installed on the side of the road, and the Pedestrian Safety Message is activated.   Also, above each of the four target crosswalks, a camera is mounted looking down at the street.  When an object enters certain areas of the video and moves in a manner consistent with a crossing pedestrian, the Pedestrian Safety Message is activated.  

About 800 vehicles currently driving around Ann Arbor are equipped with both a connected vehicle system, and a driver-vehicle interface.  The connected vehicle system is made up of a small box hidden in the rear of the vehicle and two antennas.  This device receives information from GPS satellites, processes the information, and then transmits out its own GPS location wirelessly.  It can also hear the transmissions from other vehicles and road-side equipment.  The driver-vehicle interface is simply a row of LED lights mounted in-view of the drivers and a small speaker hidden under the dashboard.  When the connected vehicle system determines that there may be the potential for a crash (another connected vehicle is stopped ahead, a pedestrian is in a crosswalk ahead) it can warn the driver by flashing the LED lights and playing warning tones or messages from the speaker (“Pedestrian Ahead”).  When a properly equipped vehicle approaches one of the equipped crosswalks, and the  connected vehicle device on-board receives a Pedestrian Safety Message from the roadside equipment, red LEDs on the dashboard light up and the speaker under the dashboard plays a voice saying “pedestrian ahead.”

Both the “pedestrian-based” method (cell phone app) and the “infrastructure-based” method (camera detection) have benefits and drawbacks.   The cell phone app could be configured to work anywhere that is in transmission range of roadside equipment (most of the city), but this would likely lead to false alarms in areas with unusual layouts.  An infrastructure-based solution can only work in one area, but it can work for all pedestrians, not just those who are actively using the cell phone application.

In this study we are examining both the effectiveness of the two different detection systems as well as the safety benefit realized when drivers can receive the pedestrian safety message.