Engineering our Highways for Older Drivers in Minnesota

Factors that affect Older Drivers and SafetyPhysical changes Strength Flexibility Range of motion

Factors that affect Older Drivers and SafetyVision Changes Visual acuity Contrast sensitivity Glare sensitivity

Factors that affect Older Drivers and SafetyCognitive changes Working memory Selective attention Processing speed

Solutions

Make the Turning Movement Easier Increase Intersection Recognition Increase Sign Visibility Improve Contrast Improve Signal Systems

Solution: Make the Turning Movement EasierAnything you do to simplify the

operation of an intersection, particularly the demands on left-turn traffic,

is an elderly mobility countermeasure.

Solution: Make the Turning Movement EasierRealign skewed intersections

Before

After

Solution: Make the Turning Movement EasierEliminate Left Turns Roundabouts

Conventional Intersection Roundabout

High speeds Low speeds

Little response time Situation changes slowly/More PRT

High energy crashes Low energy crashes

Unforgiving environment Forgiving environment

High severity crashes Low severity crashes

Complexity Easier to judge gaps

Wide visual scans Narrow visual scans

Solution: Make the Turning Movement EasierRoundabouts

Solution: Make the Turning Movement EasierIndirect Lefts Avoids interlocking left-turning movements along divided

highways Only always right-hand turns

Solution: Intersection Recognition

Solution: Intersection Recognition Flasher beacons on signs

Solution: Intersection Recognition Intersection lighting

Solution: Intersection Recognition Advance street name signs

Solution: Increased Sign Visibility

Solution: Increased Sign Visibility Larger Signs

Solution: Increased Sign Visibility Brighter signs

Prismatic sheeting that returns nearly twice as much reflected light

Solution: Increased Sign Visibility Use fluorescent yellow or fluorescent yellow-

green for ALL yellow signs

Solution: Increased Sign Visibility Use advance street name signs

Solution: Increased Sign Visibility Use curve and intersection delineation

Solution: Improve Contrast

Solution: Improve Contrast

Wet reflective pavement markings

Solution: Improve Contrast

Rumble stripes

Solution: Improve Contrast

Contrast markings

Solution: Signal Improvements

Solution: Signal improvements LED signals

Brighter than incandescent bulbs Background shields

Easier to see in cluttered environments Left turn signal phases

protects left turners from opposing traffic

All-red clearance intervals Extra time to insure the

intersection is clear

Solution: Signal improvements One signal face per lane

(centered over each lane)

Solution: Signal improvements Supplemental signal heads – always 2 signal indications for left turn

12” Lens Mast arms instead of span wire

What is good for older drivers is almost always good for all

categories of drivers.

Contact Information

Mn/DOT Office of Traffic, Safety and Technology

Sue Groth, State Traffic Engineersue.groth@state.mn.us

Dave Engstrom, Safety Engineer david.engstrom@state.mn.us

or traffic.dot@state.mn.us