Work Zone Mobility and Safety Program
Photo collage: temporary lane closure, road marking installation, cone with mounted warning light, and drum separated work zones.
Office of Operations 21st Century Operations Using 21st Century Technologies

Commercial Motor Vehicle (CMV) Safety in Work Zones


The Federal Highway Administration (FHWA), Federal Motor Carrier Safety Administration, and the National Highway Traffic Safety Administration (NHTSA) use the term CMV when referring to large trucks and buses with a gross vehicle weight or gross combination weight of 10,001 lbs or more. The NHTSA Fatality Analysis Reporting System (FARS) provides data on yearly fatal injuries in motor vehicle traffic crashes in the United States. In addition to a general data query system, FARS has specific information on trucks and buses involved in fatal crashes. FARS data indicate that in 2021, 291 of the 874 fatal crashes in work zones (33.3 percent) involved a CMV (figure 1). One sees that there has been a clear upward trend over the past 10 years.

Graph of fatal crashes over 10 year period - 2011 - 2021 with peak in 2019 for DMV fattal work zone crashes and percent of CMV involment of fatal workzone crashes.

Source: Fatality Analysis Reporting System, NHTSA.
Figure 1. Commercial motor vehicle-involved fatal work zone crashes over the past 10 yr.

Rear-end collisions were significantly overrepresented in CMV-involved fatal work zone crashes compared with CMV-involved fatal crashes outside of work zones. From 2019 to 2021, nearly 50 percent of all CMV-involved fatal work zone crashes resulted from a rear-end collision, compared with about 19 percent of CMV-involved fatal crashes outside of work zones (figure 2). Nearly 64 percent of CMV-involved fatal work zone crashes on rural interstates were rear-end collisions, as were more than 55 percent of CMV-involved fatal work zone crashes on urban interstates. Not all of the crashes were due to the CMV running into the back of another vehicle. Rather, 50 of CMV-involved fatal work zone crashes involved a collision with the CMV’s front, whereas the impact point was the CMV’s rear in 33 percent of the fatal work zone crashes. The remaining 17 percent of impacts were to the CMV’s sides.

The correlation between fatal work zone crashes and CMVs is known, and various State departments of transportation (DOTs) are taking steps to address this relationship. Through various workshops the FHWA Work Zone Management Program conducted, State DOTs shared their noteworthy practices to increase CMV safety in work zones. The following are several common noteworthy practices shared within the State DOT workshops.

Graph of CMV rear-end crashes in workzones and non-workzones from 2018 to 2021.

Source: 2019–2021 Fatality Analysis Reporting System, NHTSA.
Figure 2. Percentage of CMV crashes involving rear end collisions by land use and facility type.

Noteworthy Practices

Early consideration of CMV impacts— During project scoping and preliminary design, engineers and designers should identify potential CMV issues and suggest mitigation strategies to better accommodate CMVs. This process could include considering the temporal effects of CMVs and conducting sensitivity analyses when considering queue formation potential and selecting queue mitigation measures. This practice can also involve checking for design components that might impact CMV safety, such as lane width, shoulder width and condition, buffer space, and transition and crossover design.

Dynamic lane merge—Dynamic lane merging involves the use of changeable message signs and advanced warning signs to provide directions to drivers about when to merge based on traffic conditions. Drivers are encouraged to merge early when traffic is free flowing. When traffic slows down, drivers should use all lanes to the merge point and then take turns moving into the open lane. By establishing merging behavior based on traffic conditions, roadway users will encounter shorter queue lengths, fewer last-second-merge-related issues, and reduced road rage. Key challenges encountered when implementing dynamic lane merging involve coordination with enforcement regarding move over law requirements and driver education.

CMV left lane use—Encouraging CMVs to use the left lane is beneficial when the right lane or shoulder pavement is not meeting adequate standards and to improve merging opportunities for vehicles entering roadways via on-ramps. Various tools—such as static signs, dynamic message signs, and pavement markings—can be used to communicate this lane preference.

Improve access point designs—The movement of large CMVs into or out of a construction access point can impact safety in work zones. To avoid accidents, separate acceleration lanes, deceleration lanes, or both could be provided for construction work vehicles to gradually enter or exit at construction access points. Smart work zone technology, such as static signs with beacons and dynamic message signs, can also be added to warn roadway users of vehicles entering and exiting in work zones. Speed enforcement and education are also crucial to communicate with roadway users.

Enforcement—The addition of law enforcement can aid in improving work zone safety. Positioning enforcement on the shoulder or using automated speed enforcement can deter dangerous roadway behaviors in work zones.

Education—Including CMV safety-related information in existing work zone safety materials, developing materials explaining how roadway users should properly execute a dynamic merge, and educating drivers about safety in work zones—especially around CMVs—can reduce the likelihood of accidents in work zones.

Outreach—Trucking industry representatives and associations can be invited to participate in the project development process to help identify potential CMV issues and mitigation strategies to better accommodate CMVs earlier in the process. Transportation agencies can also inform trucking industry stakeholders about upcoming and ongoing work zones, including information about lane closures, detours, and size/weight restrictions.

Additional information can be found in the following resources.



Training Opportunities

Other Resources

For more information: contact Martha Kapitanov at

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