Traffic Operations Control For Older Drivers And Pedestrians: Summary Report

NHTSA · 1996 · ROSA P / Turner-Fairbank Highway Research Center

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Summary

This 1996 summary report from the Turner-Fairbank Highway Research Center addresses the disproportionate number of accidents involving older drivers at intersections, particularly during left-turn maneuvers. Motivated by previous studies linking these incidents to age-related deficits in useful field of vision, attention, and visual search, the investigation aimed to identify specific intersection operational characteristics that could be altered to accommodate older drivers. The study focused on two key areas: the comprehension of left-turn signalization and the physical response behaviors (decision-reaction times and deceleration) to traffic signals. The first component was a paper-and-pencil study assessing how well drivers understood various “protected” and “permitted” left-turn signal configurations. The test included standard Manual on Uniform Traffic Control Devices (MUTCD) arrangements, such as 4-lens and 5-lens vertical stacks, as well as regional variations like Delaware’s flashing red arrow, Michigan’s flashing red ball, and Washington State’s flashing yellow ball. Participants included 121 younger drivers (under 65) and 126 older drivers (over 65) from Maryland, New York, and Virginia. Subjects viewed illustrations of intersections with specific signal states and selected the appropriate driving action from a list of seven choices, such as stopping, proceeding straight, or turning left with or without yielding. The second component was a controlled field study using an instrumented vehicle to measure decision-reaction times and decelerations. Drivers navigated a closed course at 48 km/h (30 mi/h), encountering experimenter-controlled traffic signals. The protocol included loops where drivers drove normally, followed by loops where they were instructed to stop if the light changed from green to yellow, both at 32 km/h (20 mi/h) and 48 km/h. This design allowed researchers to compare the braking performance and reaction speeds of younger and older drivers under standardized conditions. The results indicated that older drivers demonstrated poorer comprehension of left-turn signalizations compared to younger drivers. However, the study found that neither group possessed a full understanding of the various signal configurations. Consequently, researchers concluded that targeting countermeasures specifically for older drivers was inappropriate; instead, efforts should focus on improving signal comprehension for the entire driving population. Regarding physical responses, there were no significant differences between younger and older drivers in decision-reaction times, the frequency of stopping on yellow phases, or deceleration rates. Based on these findings, the report determined that it is unnecessary to modify yellow signal phase timing to accommodate older drivers.

Key finding

Older drivers understood protected/permitted left-turn signals worse than younger drivers, yet neither group understood them fully.

Methodology

mixed_methods

Sample size: 247

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (7 acquisition events logged).

Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• signaling behavior
• pedal misapplication
• rail grade crossings