When it comes to making roads safer for older drivers, reducing intersection crashes is a top priority. Drivers 85 and older are more than 10 times as likely as 40-49 year-olds to be in fatal multiple-vehicle crashes at intersections.
This reflects mainly the fact that seniors get injured more easily and are less likely to survive their injuries. But among the oldest drivers, who also get in more crashes, the problem may involve age-related declines in sensory functions. Many seniors find their vision isn't as acute. Sorting out visual distractions while driving becomes more difficult. Because of cognitive changes, many seniors need more time to recognize hazards and respond.
"Intersections can be complex and dangerous, especially for older drivers and pedestrians," says Richard Retting, senior Institute transportation engineer. "Anything we can do to simplify intersections is going to be a benefit."
Converting two-way-stop intersections into four-way stops reduces crashes by about 50 percent.
Circular intersections known as roundabouts (see "Roundabout reduce traffic backups and crashes, too," July 28, 2001) significantly reduce crashes, too, especially those that involve injuries.
A short all-red phase helps to reduce crashes by clearing intersections of late-crossing traffic. Longer all-red phases could give pedestrians more time to cross.
Among people 80 and older, the pedestrian death rate is 2-3 times as high as among younger people. Longer walk signals for pedestrians could provide more time to cross. Another approach is to build islands in the middle of streets to let people cross in two stages.
Protected left turn signals
Green arrows that permit turning only when other traffic is stopped put less burden on drivers to determine when it's safe to turn. Adding turn lanes can reduce left-turn and rear-end crashes, but a trade-off is that this measure widens intersections, which could increase the risk for older pedestrians.