ATSSA: Improving Driver Behavior with Infrastructure Safety Countermeasures

5 American Traffic Safety Services Association • www.atssa.com fatal and injury single-vehicle roadway-departure collisions were reduced 13 percent to 16 percent for urban and rural freeways and 29 percent for two-lane rural roads. The Michigan Department of Transportation (MDOT) installed centerline rumble strips along approximately 5,400 miles of highways and expressways between 2008 and 2010. During an evaluation of their effectiveness, MDOT found that the centerline rumble strips reduced opposite-direction sideswipe collisions, multivehicle head- on collisions and single-vehicle roadway-departure crashes by 46 percent, 35 percent, and 31 percent, respectively. CASE 2: Roadway Signs Transverse rumble strips (also called in-lane rumble strips) are used to warn drivers in rural areas that they are approaching an intersection. The strips are grooves crossing the roadway surface to provide a tactile and audible warning for drivers. Effectiveness evaluations for this treatment applied to approaches at 154 stop-controlled intersections in Iowa and Minnesota indicate they may be effective in reducing severe-injury crashes, which could be related to a reduction in speed approaching the intersection that occurs once the driver is alerted by the noise and vibration of the rumble strip. ■ R oadway signs visually communicate regulations, warnings, directions, locations, and points of interest to drivers. These signs convey information to help drivers make better, quicker decisions while operating their vehicle. These decisions may relate to judging vehicle gaps through which to cross or turn at intersections, clearly identifying a particular street they are looking for, stopping for crossing vehicles or pedestrians, or safely navigating curves. Signs that are positioned correctly and not obstructed by vegetation or other roadside objects will clearly convey the appropriate message to the motorist. At night, some signs are brilliantly bright, and the message is clear and crisp due to “retroreflective” sheeting that is highly effective even in adverse weather conditions—day or night. Ultimately, drivers who make intelligent, informed decisions not only improve their own driving experience but often help improve driving conditions for all motorists. Today’s retroreflective sheeting technology provides for advance detection of roadway signs to notify the motorist of an upcoming change in the roadway or a warning for the motorist to make a decision soon. Figure 4. Faded, ineffective signs like this should be replaced to immediately improve roadway safety for motorists (Image: James Scott Baron, ATSSA) Advance warning signs give notice to drivers about an upcoming change in condition (such as an upcoming intersection, a reduction in speed, or the possibility of pedestrians in a school zone or a crosswalk) or the roadway environment itself. When installed correctly, these signs convey the warning message with sufficient time and distance for drivers to prepare for a change. An advance intersection warning sign provides the driver with the opportunity to make a safe lane change and adjust speed prior to turning at the intersection, reducing the potential for a rear-end crash. Additionally, roadway signs appropriately set for the speed limit of the roadway permit the driver to continue at speed without slowing down at each intersection to read a street name sign. Advance warning signs at intersections can help prevent crashes by alerting drivers that there may be traffic in their path. Prior to a curve, advance warning signs (post-mounted chevrons) notify drivers that the alignment is about to change and they should lower their current speed. Once in a curve, chevrons provide increased visibility of and delineation along a curve to help guide motorists. Retroreflective Figure 5. Retroreflective signage effectively guides motorists safely at night in a residential Virginia neighborhood (Image: James Scott Baron, ATSSA)