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The Impact of Long Term Usage and Short-Term Impairment from Cannabis on the Ability of Senior Drivers to make Safe and Beneficial Use of Advanced Vehicle Technologies


Three emerging trends will have major impacts on transportation safety and society at large. These are: (1) the aging of our society, (2) the rapid deployment of advanced driver systems in the U.S. fleet, and (3) the extent to which older drivers embrace cannabis for medical and/or recreational use as its legalization expands across the U.S. This research needs statement is concerned with the interactions among these and the potential such has for positively or negatively impacting transportation safety.

It is anticipated that the percentage of those 65 and older in the U.S. will increase by almost 55% from levels seen in 2016 to those projected in 2060 (U.S. Census Bureau, 2017). This trend will increasingly and critically stress all of society’s institutions, including transportation, in the coming decades unless equally transformative trends, policies, and/or technologies can be put into place.

One emerging technological trend which could help to address transportation problems for senior drivers is in-vehicle advanced vehicle technologies (AVT). These include not only fully autonomous vehicles, for which broad implementation may be many years in the future, but also technologies which are currently and rapidly emerging into the U.S. fleet including such key safety-related features as: adaptive cruise control (ACC), blind spot alerts (BSA), forward and rear automated emergency braking (AEB), and lane keep assist (LKA). Each of these, if properly implemented and tested with senior drivers in mind, may provide substantial help in keeping seniors driving longer and safer in their personal vehicles, thus alleviating some of the stress on the overall transportation infrastructure.

The legalization of marijuana is a “wild card” in this milieu, as the effects on driving while under the influence of cannabis impairment are just now being studied from a variety of perspectives. In particular, one uncharted area for research is the likelihood that older persons will have used cannabis long term as well as in their current lives and choose to operate a motor vehicle. Specifically, for those who do, it is unclear how long term cannabis use or short term cannabis-induced impairment affects seniors’ ability to make effective use of AVT.


U.S. Census Bureau (2017). 2017 National Population Projections Tables. https://www.census.gov/data/tables/2017/demo/popproj/2017-summary-tables.html (accessed on 1/10/2019)


The purpose of the proposed study is to evaluate the effects of cannabis usage and impairment on senior drivers’ ability to drive and make beneficial use of AVT.


The expected benefits extend to enhancing senior driver safety and mobility in the context of the key emerging trends discussed in the Background section above. Armed with this information, those stakeholders engaged with seniors can provide better advice to them, their families, and their physicians. Further, OEM or Tier 1 system designers can be better armed with information about how their systems are being used, misused, or avoided altogether. This will increase sales and profits for these entities, but more importantly this will lead to safer vehicles, drivers, and roadways for all.


Phase I: Literature Review and National Survey

o Task 1: Perform literature review – Scan latest literature in the area of the impacts of short/long term cannabis usage on senior driver behavior/performance/safety and specifically in the context of making beneficial use of the safety benefits afforded by AVT.

o Task 2: Conduct national survey

* - Task 2a:* Determine eligibility criteria (e.g., short/long term cannabis usage, driving while under the influence, ownership of a vehicle with AVT, age range, use of others as a source of comparison data (e.g., middle aged drivers))

  • Task 2b: Determine best methods to find participants, consent them, deliver survey, and compensate them; this includes procuring sample from vendors, as appropriate

  • Task 2c: Create survey content; create items to fully address the research objectives

o Task 3: *Analyze results

o Task 4: Generate final report and/or journal article(s)

o Task 5: Present results to stakeholders in other formats/venues

Phase II: On-Road Data Collection

o Task 1: Use instrumented vehicle with AVT (which is initially disabled) that is ‘loaned’ to each participant for one month, to allow acclimation in order to obtain baseline measures of following distance, braking behavior, ‘dilemma zone’ choices, and responses to unexpected hazards

o Task 2: Characterize differences/variability in sample with respect to all behaviors

o Task 3: After obtaining baseline measures naturalistically, introduce AVT with both naturalistic driving and naturalistic driving that translates seamlessly to a controlled environment where responses to specific experimentally induced perturbations could be measured in a way that could not be done safely or ethically in a naturalistic study.

o Task 4: Examine differences/variability in sample with respect to all behaviors, with hypothesis that behaviors with negative safety implications will be ameliorated.

* *

Sample: Drivers aged 60-75, 75+, and possibly a middle-aged control group; both ‘medical’ and ‘recreational’ users may participate – all must agree to a toxicology analysis, and to provide self-report of what, when, and how much cannabis product has been consumed and over what period of time in the past.


The proposed study is envisioned in two phases:

Phase I, as specified above, should have a high probability of success with few barriers. This initial step could lead to follow-on studies (Phase 2) where actual behavioral and performance data are collected on test track(s) and/or in the real-world using naturalistic methods also has a high probability of success, as these techniques have been successfully applied for many years.


The potential users of this research are all stakeholders concerned with senior mobility and safety in today’s world of emerging technology on the one hand and the growing trend of permissiveness regarding cannabis usage across the U.S. These include Federal and state DoTs, DMVs, urban planning commissions, physicians, OEMs and Tier 1 suppliers, and all seniors and their family members.

Sponsoring Committee:ANB60, Safe Mobility of Older Persons
Research Period:Longer than 36 months
Research Priority:High
RNS Developer:Jon Antin, Ph.D., CHFP, VTTI; Loren Staplin, Ph.D., TransAnalytics
Date Posted:03/01/2019
Date Modified:05/21/2019
Index Terms:Marijuana, Aged drivers, Impaired drivers, Driver support systems, Drug use, Drugged drivers,
Cosponsoring Committees: 
Safety and Human Factors
Vehicles and Equipment

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