Older Driver Performance across Six Naturalistic Studies [Traffic Tech]

Staplin, L.; Lococo, K. H.; Mastromatto, Tia; Sifrit, Kathy · 2021 · ROSA P / United States. Department of Transportation. National Highway Traffic Safety Administration

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Summary

This report addresses the challenge of balancing mobility and safety for older adults, a demographic that constituted 16% of the U.S. population and 20% of licensed drivers in 2018. As the population ages, understanding how age-related physical and cognitive changes affect driving behavior is critical. The study synthesizes data from six National Highway Traffic Safety Administration (NHTSA)-sponsored naturalistic studies and compares findings with data from the Strategic Highway Research Program 2 (SHRP2) to determine relationships between functional status, driver performance, and driving exposure. The NHTSA combined dataset included participants from Virginia and the Carolinas, with sample sizes ranging from 20 to 60 per study. Data collection involved clinical measures of functional status, formal driver performance evaluations by certified driver rehabilitation specialists, and naturalistic driving exposure data collected over up to one month. To address limitations in sample size and duration, the analysis also incorporated SHRP2 data, which included 1,045 drivers aged 60 and older from across the United States, instrumented for one to two years. Both datasets utilized similar functional testing protocols, allowing for comparative analysis of how cognitive and physical capabilities influence on-road behavior and crash avoidance. The analysis of the NHTSA combined data revealed only weak correlations, accounting for at most 10% of the variance, between functional status, driver performance, and driving exposure. While poorer functional scores were associated with lower trip speeds and higher error scores, the associations were inconsistent, potentially due to subjective evaluation protocols and limited geographic scope. Similarly, the larger and longer-duration SHRP2 dataset showed weak relationships between functional status and driving exposure. These findings indicate that healthy older adults’ decisions regarding when, where, and how often to drive are driven primarily by habits and mobility needs rather than their fitness levels. However, SHRP2 data did identify specific performance deficits in crash scenarios; drivers with serious cognitive impairment exhibited a statistically significant longer "Latency 1" interval (time to perceive a peripheral threat) by 0.3 seconds compared to those without impairment, highlighting vulnerabilities in peripheral scanning. The significance of these findings lies in the conclusion that functional ability has little influence on the self-regulation of driving exposure among healthy older adults. Consequently, relying on functional status to predict driving habits is ineffective. Instead, the results underscore the need for precise research framing regarding how aging affects crash avoidance behaviors, particularly in peripheral conflicts. The study suggests that safety interventions should focus on countermeasures that address specific behavioral vulnerabilities, such as reduced scanning, rather than assuming older drivers will naturally limit their exposure based on their functional decline.

Key finding

Functional and cognitive status correlated only weakly with driving exposure in both the combined NHTSA data and the 1,045-driver SHRP2 sample, accounting for at most about 10% of the variance.

Methodology

naturalistic

Sample size: 1045

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

Ranked by relevance to this paper. Hover a topic for its definition.

• older drivers
• mci dementia driving
• cognitive capacity variation
• older driver retraining
• age related perceptual decline
• sex gender

Information type

What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).

• Empirical Findings: observational prevalence, crash risk outcomes
• Methodological Resource: dataset resource