Visibility of children behind 2010-2013 model year passenger vehicles using glances, mirrors, and backup cameras and parking sensors.
This study identified the areas behind vehicles where younger and older children are not visible and measured the extent to which vehicle technologies improve visibility. Rear visibility of targets simulating the heights of a 12-15-month-old, a 30-36-month-old, and a 60-72-month-old child was assessed in 21 2010-2013 model year passenger vehicles with a backup camera or a backup camera plus parking sensor system. The average blind zone for a 12-15-month-old was twice as large as it was for a 60-72-month-old. Large SUVs had the worst rear visibility and small cars had the best. Increases in rear visibility provided by backup cameras were larger than the non-visible areas detected by parking sensors, but parking sensors detected objects in areas near the rear of the vehicle that were not visible in the camera or other fields of view. Overall, backup cameras and backup cameras plus parking sensors reduced the blind zone by around 90 percent on average and have the potential to prevent backover crashes if drivers use the technology appropriately.
The ability of rear-mounted convex mirrors to improve rear visibility
The Cameron Gulbransen Kids Transportation Safety Act of 2007 requires the National Highway Traffic Safety Administration (NHTSA) to “initiate a rulemaking to revise Federal Motor Vehicle Safety Standard 111 to expand the required field of view to enable the driver of a motor vehicle to detect areas behind the motor vehicle to reduce death and injury resulting from backing incidents, particularly incidents involving small children and disabled persons.” It goes on to state that this may be accomplished “by the provision of additional mirrors (emphasis added), sensors, cameras, or other technology to expand the driver’s field of view.” An advanced notice of proposed rulemaking was published on February 27, 2009. This paper examines whether rear-mounted convex mirrors could provide an image with sufficient quality that may be useful in aiding drivers in performing backing maneuvers. There are three main configurations of rear-mounted convex mirrors: a single “look-down” mirror, a single corner mirror, and a pair of cross-view mirrors. NHTSA measured fields of view and image quality of one look-down mirror and three pairs of crossview mirrors for passenger vehicle applications. Field of view and image quality were also estimated for one rear convex corner mirror based on previous research with that mirror relating to its use on medium straight trucks. Note that this study did not attempt to examine whether drivers will successfully use rear-mounted convex mirrors to successfully detect obstacles or pedestrians behind a vehicle. This question of potential overall effectiveness of rearmounted convex mirrors, relative to other solutions to expand the driver’s rear field of view, will be the subject of additional agency research. The useful fields of view (FOV) of the five rearmounted convex mirrors were determined. The potential backover risk reductions were estimated for the five mirrors studied, using only that portion of their FOV’s with an image quality rating of better than “impossible.” The estimated potential backover risk reductions ranged from 33.4 percent (for the Toyota 4Runner rear cross-view mirrors) to 2.2 percent (for the ScopeOutTM passenger car rear crossview mirror).
Field Measurement of Naturalistic Backing Behavior
A series of observations and measurements were made as subjects drove their own vehicles in an assortment of naturalistic backing tasks conducted on public roads in real world driving conditions. As the subjects performed eight backing tasks, the following data were collected: glance direction, hand position, velocity and acceleration, and distance to object in back of the vehicle. The results provide a set of normative data usable by automotive system designers for the design of backing warning systems and other ITS applications. The results of this study were divided into glance direction, backing speed, and time-to-collision. Glance directions were found to vary greatly between tasks. Elderly drivers demonstrated more use of their mirrors and looked over their shoulder less then the young drivers. Looking over the right shoulder was the most frequent glance location across all tasks. Except for the extended backing maneuvers, backing speeds averaged around 4.8 km/h (3 mph). The maximum backing speed for the young drivers was faster than the elderly and males backed faster than females. The time-to-collision was relatively constant over the majority of the backing sequences. Minimum time-to-collision values were generally over 2 seconds.