Decriminalization of Marijuana and Potential Impact on CMV Drivers

by Kathryn Slater, UMTC Research Staff

Captain Darrin Grondel is the Director of the Washington Traffic Safety Commission and a Captain with the Washington State Patrol. At the 2016 Commercial Vehicle Safety Research Summit, Captain Grondel discussed drugged driving and its impact on traffic safety. The following are some highlights of Captain Grondel’s presentation.


As marijuana becomes legal for recreational use across the country, transportation safety stakeholders grapple with the realities and challenges inherent in the new legislation. Currently, the possession and use laws in the U.S. are described as a patchwork, as their look and structure remain very different, depending on the state.

What’s more, the strength of marijuana has changed dramatically over the last several decades. While most governmental studies involving marijuana involve THC levels of 3-6%, the substances now showing up in a variety of forms (oils, edibles, vaping) have THC levels closer to 30-40%.  While many issues around legalization of marijuana remain unclear, what we do know is that incidences of drugged driving are going up, and must be mitigated.

The overarching issue around legalization of marijuana remains the existing knowledge gap around the effects of cannabis (and other drugs) on driving. One reason for this gap is a complete lack of data around drugged driving; including crash and inspection data, and information about the types of drugs being used, and in which combinations.

Another major issue is public indifference. Drivers tend to see drunk driving as clearly dangerous and socially unacceptable, but don’t feel strongly one way or the other about drugged driving. Many people don’t know the level at which drugs impair them, and haven’t been educated about the dangers of driving while taking something as benign-seeming as cough medicine. The Pacific Institute for Research and Evaluation conducted the PIRE Roadside Survey in 2014 and 2015, where they surveyed 926 drivers in 5 counties. Of drivers who said they’d used marijuana within two hours of driving, 67% said that it made no difference in their driving. Knowing what we do about the effects of THC on the brain, it seems unlikely that drivers would be unaffected.

What remains clear is that drugged driving is much more complicated than drunk driving, and that these types of crashes are on an upward trend. Less clear, are the details around how drivers are affected, how long those effects last and how police will know a drugged driver when they see one.

2016 Commercial Vehicle Safety Research Summit

The University of Massachusetts Traffic Safety Research Program (UMassSafe) held a Commercial Vehicle Safety Research Summit in November of 2016 to promote best practices for advancing safety through partnerships among law enforcement and state driver’s license agencies with universities.  With more than 100 attendees from across the Northeast, the 2-day Summit, funded by the Federal Motor Carrier Safety Administration (FMCSA), addressed key issues related to crash prevention including driver distraction and autonomous vehicles, as well as homeland security, drugged driving, social media and workforce development.


“Innovation is rapidly changing the transportation sector.  The Federal and state governments must keep up while never losing sight of protecting the traveling public,” said FMCSA Deputy Administrator Daphne Jefferson, one of the keynote speakers. “This summit enables us to learn from each other and build partnerships with universities to realize the safety benefits of innovation and automation.”

The goals of the summit were based upon the premise that an integrated approach and effective partnerships can reduce the number of truck and bus crashes and fatalities.  Massachusetts has enjoyed positive safety results because of the successful partnership that now exists between UMassSafe, the Massachusetts State Police Commercial Vehicle Enforcement Section and MassDOT’s Registry of Motor Vehicles Division. Using this experience as an example, summit organizers encouraged other state participants to develop or expand the connection between universities and state agencies involved in crash prevention efforts.

The FMCSA funded project continues with the implementation of a UMassSafe Technical Assistance Center (TAC) in order to provide assistance for law enforcement and licensing agencies as well as universities, acting as a resource and information center building on the momentum of the Summit.  Additional information can be accessed at

By: Robin Riessman, UMassSafe

T-Force Toolkit : Increasing Truck and Bus Traffic Enforcement

For a variety of reasons, routine traffic stops with large trucks and buses occur significantly less than traffic stops with passenger vehicles. Considering the detrimental effects of these crashes, it is critical that we incorporate truck/bus traffic enforcement into existing highway safety activities.

With this growing issue in mind, the University of Massachusetts Traffic Safety Research Program (UMassSafe) developed T-Force, Truck and Bus Traffic Enforcement Toolkit, providing a free one stop shopping tool for resources geared toward traffic patrol officers. T-Force is a three-part program with a goal of increasing the enforcement of moving violations such as speeding and lane violations. Different than programs aiming to inform specialized Motor Carrier Safety Assistance Program (MCSAP) officers, this information is intended for a wider audience, particularly officers conducting regular traffic enforcement.

The T-Force Toolkit is comprised of three main sections; including Fast Facts, Instructors Portal and Web Resources.

  • Fast Facts: This section of the Toolkit offers detailed information regarding the importance of traffic stops with trucks/buses, strategies for maintaining officer safety, how truck/bus traffic stops are different than those with passenger cars, the process of conducting an effective traffic stop and the details involved in CDL. Users can move quickly through this interactive tool, accessing only the information they need.
  • Instructors Portal: This section provides access to all of the materials needed to conduct the Safe and Effective Traffic Stops: Truck and Bus Traffic Enforcement training. This training, developed by UMassSafe, is currently being taught in several states across the country for local and state traffic patrol officers. Instructors can access all course materials on the website, including a guide for both instructors and participants as well as the PowerPoint presentation.
  • Web Resources: The web resources section provides access to an online library of videos, a discussion board to ask and answer questions, and links to other trainings and online resources.

For additional information

UMassSafe is a multidisciplinary traffic safety research group housed in the UMass Transportation Center at the University of Massachusetts. With the unique ability to examine highway safety from a variety of perspectives, UMassSafe provide tools and information in a format that is practical for a wide range of users from law enforcement personnel to statisticians at federal agencies. Working on issues related to commercial motor vehicle safety for over 15 years, UMassSafe has developed data query tools, crash corridor maps, and police training as well as conducted extensive crash data analysis and data quality improvement projects.

Written by Robin Riessman and Jennifer Gazzillo, UMassSafe