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Truck Side Guards Resource Page

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.

The U.S. DOT Volpe Center is advancing this technology’s adoption in the United States by conducting research and partnering with public- and private-sector fleets to help deploy side guards and other technologies that address the deadliest road crashes: those between large trucks and pedestrians or bicyclists.

While large trucks comprise 4 percent of registered vehicles, large trucks are involved in 10 percent of pedestrian and bicyclist fatalities. In 2016, these fatalities rose to 468, the highest since 1990.

The U.S. DOT Volpe Center 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.

Peruse the full page or jump directly to the following sections:

How it Works

During a crash with a truck or other vehicle with high ground clearance, vulnerable road users can fall into the exposed space between the front and rear wheels and suffer fatal crushing injuries.
A close-up of a side guard on a truck.

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.

Reducing Fatalities

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.

A graphic of a truck with statistics related to fatalities caused by impact with the side of a truck.

Based on studies conducted in the United Kingdom, Australia, Sweden, and the Netherlands, 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 guard relevant 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.

A chart showing the side skirts at a four to seven percent fuel economy improvemet.nWhile side skirts are primarily designed to reduce fuel consumption, this technology may also protect vulnerable road users in side-impact collisions.

A number of side skirt manufacturers have already verified that their panels can meet side guard structural requirements with few or no modifications. Canadian and Dutch research also suggest that certain side skirts may provide protection that’s comparable to that of side guards. Thus, a dual-purpose side guard/skirt may provide both vulnerable road user safety and fuel return on investment to the owner.

Implementation in the U.S. and Abroad

Global Timeline

Side guards have been required standard equipment since 1979 in Japan, the 1980s in the European Union and China, and more recently in Brazil, Peru, and Mexico City. 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.

U.S. Adoption

A photo of a Boston Public Works truck with sideguards installed.There has been growing side guard adoption in the United States at the local and private-sector levels, including dozens of private fleets and municipal or city-contracted fleets in over a dozen cities from coast to coast.

U.S. map with pinpoints showing side guard adoption in San Francisco; Washington, D.C.; Orlando and Fort Lauderdale; Chicago; Boston, Cambridge, Somerville, and Newton, MA; New York City; Portland, OR; Philadelphia; and Seattle.
Implemented and pending side guard adoption by cities in the U.S. (Volpe image) 

Research and Resources

The U.S. DOT Volpe Center has a significant library of literature on truck side guards and is building a national network of adopters in the areas of truck side guards, high-vision cabs, automatic emergency braking systems, and other truck safety technologies relevant to vulnerable road users. (For more information, contact Dr. Alexander Epstein at

The following U.S. resources offer an introduction to this research:

  • Boston Truck Side Guard Ordinance
    View publication
  • Cambridge Safer Truck Initiative: Vehicle based strategies to protect pedestrians and bicyclists (March 2016)
    View publication
  • National Transportation Safety Board (NTSB) Study: Crashes Involving Single-Unit Trucks that Resulted in Injuries and Deaths (June 17, 2013)
    View publication
  • NTSB Safety Recommendations to NHTSA regarding side guards for tractor-trailer trucks (April 3, 2014)
    View publication
  • NTSB Safety Recommendations to NHTSA regarding side guards for single-unit trucks (July 3, 2013)
    View publication
  • NYCDOT Hunts Point Clean Trucks Program Side Guard Vendor List
    View web page
  • 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)
    View publication
  • Truck Side Guard Ordinance: Boston, MA (FHWA case study, March 2017)
    View PDF or HTML page
  • Truck Side Guard Technical Overview: Safety and Operational Considerations (fact sheet, March 2017)
    View publication
  • Truck Side Guard Technical Specifications: Recommended Standard DOT-VNTSC-OSTR-16-05 (September 2016)
    View publication
  • Truck Side Guards for Vision Zero: Review and Technical Recommendations for Safe Fleet Transition Plan Pilot Deployment (December 2014)
    View publication
  • Vision Zero San Francisco Truck Side Guard Initiative: Technical Assessment and Recommendations (May 2016)
    View publication

International Research

  • Dutch Road Safety Research Institute: Closed Sideguards on Trucks: Less Fuel Consumption for Trucks, Safer Feeling for Vulnerable Road Users
    View publication
  • National Research Council Canada: Side Guards for Trucks and Trailers: Phase 1: Background Investigation
    View publication
  • Great Britain Department for Transport: Integrated Safety Guards and Spray Suppression: Final Summary Report
    View publication

Video Highlights

Side Guards: How They Work
U.S. DOT Volpe Center crash tests demonstrate how side guards can help save lives when large trucks and vulnerable road users collide.

Side Guards: Saving Lives, Saving Fuel
U.S. DOT Volpe Center 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
U.S. DOT Volpe Center engineer Alex Epstein discusses side guards and other technologies that address the deadliest road crashes: those between large trucks and pedestrians or bicyclists.

Updated: Thursday, June 6, 2019