Truck side guards are vehicle-based safety devices designed to keep pedestrians, bicyclists, and motorcyclists from being run over by a large truck’s rear wheels in a side-impact collision.
Volpe is advancing this technology’s adoption in the United States by conducting research and partnering with cities to help deploy side guards and other technologies that address the deadliest road crashes: those between large trucks and pedestrians or bicyclists.
Volpe is also building a national network of early adopters in the area of truck side guards and other truck safety technologies related to pedestrians, bicyclists, and motorcyclists—known as vulnerable road users.
This page is intended to offer general knowledge and resources for municipalities as well as private sector businesses that are seeking information or considering adopting this technology.
How it Works
During a crash with a truck that has high ground clearance, vulnerable road users can fall into the exposed space between the front and rear wheels and suffer fatal crushing injuries.
Side guards work by physically covering that exposed space, shielding vulnerable road users from being swept underneath the truck’s rear wheels.
This technology can be retrofitted onto existing trucks or incorporated into new vehicle fleets.
Learn more by reading the Truck Side Guard Technical Overview: Safety and Operational Considerations.
Crashes involving large trucks are more likely to result in a pedestrian or bicyclist fatality than crashes involving passenger vehicles. Truck crashes are also more likely to be side-impact crashes.
Based on studies conducted in the United Kingdom, side guards are an effective technology for reducing the number of vulnerable road user fatalities and the severity of injuries, especially for bicyclists.
- Following the national side guard mandate in the UK, there was a 61 percent drop in cyclist fatalities and a 20 percent drop in pedestrian fatalities in side-impact collisions with trucks.
Improving Fuel Economy
Aerodynamic truck side skirts (or underbody fairings)—a technology similar to side guards—are primarily designed to save fuel for trucks by decreasing air drag.
- Side skirts provide 4 to 7 percent fuel economy improvement (verified by EPA SmartWay).
- Annual fuel savings from installing a rigid side skirt can reach $5,000 for a long-haul tractor trailer, depending on mileage and speed.
While side skirts are primarily designed to reduce fuel consumption, this technology may also protect vulnerable road users in side-impact collisions.
Canadian and Dutch research suggest that certain side skirts may provide protection that’s comparable to that of side guards. Thus, a dual-purpose side guard/skirt may offer both vulnerable road user safety and fuel return on investment.
Implementation in the U.S. and Abroad
Side guards have been required standard equipment since the 1980s in the European Union and Japan, and more recently in Brazil. Canada conducted research for a national side guard standard from 2009 to 2013 and also began evaluating the viability of using aerodynamic side skirts for vulnerable road user safety.
There has been limited but growing side guard adoption in the United States that includes municipal truck fleets in Portland, OR, and Washington, D.C., and recently Boston, Cambridge, and New York City, which partnered with Volpe to develop recommended specifications.
Research and Resources
Volpe has a significant library of literature on truck side guards and is building a national network of early adopters in the areas of truck side guards and other truck safety technologies related to vulnerable road users. (For more information, contact Dr. Alex Epstein at Alexander.Epstein@dot.gov.)
The following U.S. resources offer an introduction to this research:
- Truck Side Guard Technical Overview: Safety and Operational Considerations
- Truck Sideguards for Vision Zero: Review and Technical Recommendations for Safe Fleet Transition Plan Pilot Deployment
- Boston Truck Side Guard Ordinance Handout (requirements and specifications)
- Cambridge Safer Truck Initiative: Vehicle based strategies to protect pedestrians and bicyclists (March 2016)
- Review and Analysis of Potential Safety Impacts of and Regulatory Barriers to Fuel Efficiency Technologies and Alternative Fuels In Medium- and Heavy-Duty Vehicles (June 2015)
- National Transportation Safety Board (NTSB) Study: Crashes Involving Single-Unit Trucks that Resulted in Injuries and Deaths (June 17, 2013)
- NTSB Safety Recommendations to NHTSA regarding side guards for tractor-trailer trucks (April 3, 2014)
- NTSB Safety Recommendations to NHTSA regarding side guards for single-unit trucks (July 3, 2013)
- Dutch Road Safety Research Institute: Closed Sideguards on Trucks: Less Fuel Consumption for Trucks, Safer Feeling for Vulnerable Road Users
- National Research Council Canada: Side Guards for Trucks and Trailers: Phase 1: Background Investigation
- Great Britain Department for Transport: Integrated Safety Guards and Spray Suppression: Final Summary Report
Side Guards: Saving Lives, Saving Fuel
Volpe engineer Alex Epstein presents the idea of using side guards as a means to make trucks safer.
Blind Spot Demonstration
A truck driver demonstrates the extent of a driver's blind spot.
Protecting Pedestrians and Bicyclists, One Safer Truck at a Time
Volpe engineer Alex Epstein discusses side guards and other technologies that address the deadliest road crashes: those between large trucks and pedestrians or bicyclists.