Engineer and planner resources
Engineering and planning for the elder road user takes into account the changes in vision, fitness and flexibility, attention span, and reaction time that occur as we age. Engineering and planning with Iowa's aging population in mind is critical to the mobility of Iowa's seniors and has the added benefit of improving safety for everyone.
Improvements that benefit mature drivers
The Iowa Safety Management System (SMS) facilitated a Safe Mobility Decisions for Older Drivers Forum in 2002, where several engineering improvements were identified as priorities for older road users including the following.
- Improve pavement markings and delineation: Brighten markings with wet-reflective tape, raised pavement markers or special paints; maintain edge markings and centerline markings with more durable materials or more frequent applications; widen 4-inch pavement markings to 6 inches or wider; install plowable raised pavement markings on curves of two-lane roads or other specific application locations that can be plowed.
- Improve shoulders: Widen shoulders; pave shoulders (minimum 24 inches, ideally 6 feet); install rumble strips.
- Improve intersections: Differentiate better between two-way and four-way stops; use dilemma zone protection at high-speed intersections when warranted; install protected left turn signals; install destination lighting at rural intersections.
- Improve driver cues from signs, signals and lighting: Install better lane and route designation cues (word or diagram on a sign); install advance street name signs; use larger visual signals.
- Improve roadway design features: Create more and longer turn lanes; install shoulder and centerline rumble strips.
Other helpful resources for planners and engineers include the following.
- The NCHRP Report 500 – Guidance for Implementation of the AASHTO Strategic Highway Safety Plan Series includes A Guide for Reducing Collisions Involving Older Drivers. This guide provides engineering, planning, education, and policy guidance to highway agencies on how to better accommodate older drivers’ needs. To view a copy of this guide, click here or visit the Transportation Research Board's Web site at http://trb.org.
- The Federal Highway Administration’s (FHWA) Highway Design Handbook for Older Drivers and Pedestrians is a resource for engineers, which provides practical guidance on how to accommodate the needs and functional limitations of the older driver on both new and existing roadways. For more information, click here or visit http://www.tfhrc.gov/humanfac/01103/coverfront.htm.
- The FHWA’s Office of Operations prepared A Pocket Guide to Improve Traffic Control and Mobility for Our Older Population to help transportation professionals account for the unique needs of the nation’s increasing older population when making decisions on traffic control devices. The guide focuses on intersections and interchanges, curves and temporary traffic control zones. For more information, click here or visit FHWA's Web site at http://mutcd.fhwa.dot.gov.
Seniors sometimes experience difficulty crossing the street because their walking speeds tend to slow with age. Refuge islands, particularly for multi lane highways, can provide older pedestrians a safe place to wait for the signal to change and countdown pedestrian signals provide older pedestrians with information on how much time remains to safely cross the street. There are several resources on designing safe pedestrian facilities for older road users including the following.
- The AAA Foundation on Traffic Safety report on Pedestrian Signal Safety for Older Persons investigated the walking speed of older pedestrians at signalized intersections. The study found that in most cases the walking speed of older pedestrians was faster at intersections with the pedestrian countdown signals compared to traditional signals. To view this study, click here or visit the foundation's Web site at http://www.aaafoundation.org.
- The Pedestrian and Bicycle Information Center is a national clearinghouse of information related to pedestrians and bicyclists. Their web site includes a section on Designing for Special Pedestrian Populations. To view a copy, click here or visit the Center’s Web site at: http://www.walkinginfo.org/engineering.
Intersections can be the most dangerous of roadway features and pose a greater safety risk for older drivers who may have problems judging the speed and distance of conflicting traffic movements.
The FHWA Publication - Public Roads, January/February 2007, Vol. 70, No. 4, "Older Drivers at a Crossroads," summarizes various design and operational improvements that have been implemented and found to improve the safety of older drivers at intersections. To view a copy of this report, click here or visit http://www.tfhrc.gov/pubrds/07jan/02.htm.
Protected left-turn lanes that use a dedicated left-turn signal, assist the older drivers who often have trouble making left turns due to an inability to accurately judge the speed and distance of the approaching traffic. The following studies investigate the effectiveness of protected left-turn lanes and signal phases.
- The Center for Transportation Research and Education at Iowa State University conducted the study, “Impact of Left-Turn Phasing on Older and Younger Drivers at High-Speed Signalized Intersections” and found that protected left-turn phasing reduced the crash experience for older drivers compared to protected/permitted phasing or permitted phasing. To view this report, click here or visit the Center’s Web site at http://www.ctre.iastate.edu.
- FHWA Publication "Safety Effectiveness of Intersection Left- and Right-Turn Lanes" provides a summary of intersection safety studies and can be accessed by clicking. To view a copy, click here or visit http://www.tfhrc.gov.