A Helpful Guide to the Rear Underride Guard Rulemaking

This is a crash picture free zone.

The current stiff rear underride guard standards are a safety compromise that do not protect all sizes and weights of current vehicles. They ultimately are too stiff for small vehicles or are too weak for large vehicles. Only energy-absorbing guards provide protection for most sizes and weights of current vehicles and modern designs are cheap and simple to implement. Any new rear underride guard standard should be an energy-absorbing guard standard to reflect state-of-the-art research and interact properly with modern vehicle designs.

In 2015, the U.S. still allows deadly guillotine guards on the backs of all single-unit trucks and many specialty trailers, including all trailers built prior to 1998. Is this 1952 safety regulation the best the U.S. government can achieve after 63 years? These false guards do not prevent underride even at low speeds and cannot be considered state-of-the-art in civil litigation.

In the U.S., as many or more have been killed and injured in truck crashes than in all of the wars this nation has fought since it was founded. This holiday season stop and think about all of the families that have given everything so that package could arrive at your doorstep. We do not ask for monuments, we do not ask for bronze plaques, we just ask that they be remembered and that the next child, or mother, or father, or grand parent be saved or at least be given a fighting chance. Please support life-saving underride guards for all trucks and trailers and remind the U.S. DOT to remember those they did not save, so that they can remember those they might save in the future.


UNICAMP CRASH TEST PICUnderride Guard Crash Test – UNICAMP Impact Project Photo
High speed guard design due to attachment strength and
stiff braces to far outside edge of guard for offset impacts

Mother loses daughters, raises truck underride concerns at The Indy Channel.

“”This type of accident usually involves serious driver error, so the Truck Trailer Manufacturers Association notes first that the rules already in place to prevent these accidents must be followed, including regulations against speeding or driving while impaired or distracted,” wrote Jeff Sims, TTMA president, in an emailed statement to RTV6.”

The TTMA in essence recommends prosecuting victims and we must conclude keeping the death penalty for human error and mistakes through the use of at best 30 mph underride guards. The TTMA represents Trailer Manufacturers and Major Automobile Manufacturers including U.S. Car Companies. The U.S. government because of millions in campaign donations has allowed this organization to lobby on these issues while blocking input from U.S. survivors of crashes including U.S. experts that represent victims on these types of crashes and outcomes. Underride victims are blocked from all input.

We are using this page to provide tips and information for submitting comments for the upcoming NHTSA Rear Guard Rulemaking, please send us your tips, links to research, and comments. We will link to other safety sites recommendations when they are available. We will keep this page and the side and front underride guard rulemaking pages crash picture free due to popular request.


You can cut and paste statements to make your point in your comments to the rulemaking such as Single-unit trucks should be included in the standard, NTSB says: “Although single-unit truck crashes are neither as lethal nor as likely to cause the most severe injuries as compared with tractor-trailer crashes, available data show that they are involved in at least 37 percent of the fatalities, 49 percent of inpatient hospitalizations, and 61 percent of emergency department visits from large truck crashes.”

Our friends from other countries may also send in comments to the U. S. Rear Guard Rulemaking. The standard the U. S. adopts will affect standards in other countries, weak in the U. S. will also mean weaker in your country. Let them know you are commenting as a friend of the Underride Network which is a U. S. based International Organization.

Here is the link to post comments to the proposed rule:

Here is a link to our guide to post comments for NHTSA Rear Guards Rulemaking.

Luis Otto Faber Schmutzler from UNICAMP states “motivated by the desire of saving human lives, whenever possible by applying the logic and philosophy of safety engineering, we present below a critical analysis of the new American Standards. This work is of fundamental importance, since at least in the developing countries, traffic agents will copy the so-called American solutions and in so doing will spread the tragedy worldwide…”

American Standards Rear Guards: Comments

We recommend engineering schools encourage their students to submit comments on the new standard, share with us and we will post here on the site.

NHTSA proposed rear impact guard regulations for trucks in 1969 and 1981 that were never acted upon. We are concerned there has been no activity on this announced rulemaking evaluation.

The new NHTSA Administrator is an expert on fatigue issues but it seems clear the most promising areas to save the most lives including from fatigue are in technology and vehicle crash compatibility. High speed underride guards, including rounded ends and angled bracing at ends of guards and extension from the vehicle can protect car occupants even at high speeds, simple and low cost. Vehicle obstruction detection braking or warning systems on all new vehicles would prevent inattention and fatigue crashes including failure to stop during fog, accident, or road repair situations. Lane scanning technology on all new vehicles could guard against side of road crashes and combat fatigue and impaired driving, could include 3 strikes and your out cease operation alarms or warnings. Vehicle to vehicle communications could warn of slow downs and roadway obstructions. We are where we should have been years ago in all of these issue areas and lives have already been lost while less effective arguments in vehicle safety have eaten up all of the available bandwidth. People are dying, NHTSA needs to take some action, any action would be an improvement. Legalizing guards already on American roadways as NHTSA now proposes will not improve safety.

NHTSA: “According to NHTSA data, one-third of all police-reported crashes in 2013 involved a rear-end collision with another vehicle at the start of the crash. The agency also found that a large number of drivers involved in rear-end crashes either did not apply the brakes at all or did not apply the brakes fully prior to the crash. Crash imminent braking and dynamic brake support systems can intervene by automatically applying the vehicle’s brakes or supplementing the driver’s braking effort to mitigate the severity of the crash or to avoid it altogether. These AEB systems, along with promising innovations such as vehicle-to-vehicle communications (V2V) and automated vehicle technologies hold great promise to save even more lives and prevent even more crashes, building upon the successes of crashworthiness and crash avoidance technologies currently available in vehicles today.”

NTSB 2015 MOST WANTED TRANSPORTATION SAFETY IMPROVEMENTS – Strengthen Commercial Trucking Safety – Factsheet in PDF

Hearing on Surface Transportation Reauthorization:

Oversight and Reform of the Federal Motor Carrier Safety Administration Washington, DC March 4, 2015

National Transportation Safety Board (NTSB) : To address vehicle factors, regulators must promote proper fleet maintenance and proven life-saving technology. Vehicle inspections should be required during compliance reviews, and vehicle safety equipment and technology, such as collision warning technology, tire pressure monitoring systems, rollover stability control systems, and lane departure warning systems, should be mandated across the entire industry. Regulators should also develop performance standards for front and side underride protection systems to improve highway vehicle crash compatibility with passenger vehicles.

U.S. Transportation Secretary Anthony Foxx Launches the “Mayor’s Challenge for Safer People and Safer Streets”

Mayor’s and local elected officials can attend a Safer People, Safer Streets Summit and then take significant action over the next year to improve pedestrian and bicycle transportation safety. The Mayor’s Challenge will showcase effective local actions to improve safety, empower local leaders to take action, and promote partnerships to advance pedestrian and bicycle safety.

This is a chance for cities and local bicycle associations to push for front and side guards on trucks. Regulation on side guards is coming next!

We need comments and safety links, articles etc. from bicyclists perspective, let your Org. know it is time to get involved!

NHTSA will probably use an Advance Notice of Proposed Rulemaking (ANPRM) prior to the issuance of the NPRM. NHTSA uses the ANPRM to get early public participation for a variety of reasons, including when NHTSA wants comments on how to solve a problem before making a proposal and/or have identified a wide range of alternatives and want to narrow the choices before making a proposal and/or needs additional information to help analyze the problem and its solutions. We will have trucks and trailers covered or not covered under the new rule based on the date of their manufacture. We will have 3 Standards, one from 1953 for trucks and trailers, one from 1998 for trailers only, and the new one from 2016 or later year possibly covering new trucks and trailers only. Trailers older than 2016 or later year will be covered either by the 1998 standard if built after 1998, or covered by the 1953 Standard if they were built prior to 1998. New trucks might be covered by the 2016 or later year Standard if they are added to the Standard, trucks built prior to 2016 or later year would be covered by the 1953 Standard. The 1953 Standard would still be the catchall for some exempted vehicles that still require some type of guard. This is basically what this process should look like, of course, all of this is conjecture and subject to change.

We are still arguing for the same MUARC style energy absorbing guards we were arguing for back in 1992. We are still arguing for the same fluorescent tape colors to vastly increase the conspicuity of trucks and trailers that we argued for years ago. We can look back at the arguments of CRASH, Advocates, and IIHS and they are basically the same they will make today. (CRASH press release concerning new guard standard: Archived.) NHTSA was wrong and cars did drastically change, we now have much lighter and smaller cars with crush zones and engineered survivable passenger compartments. We have air bags. Cars will change in the next 20 years. Guards could be stiffer today with the car able to provide the energy absorption with their crush zones and engineered frames but we do not argue for minimums. We did not in 1992 and we do not now because people die. They die in large numbers. When NHTSA denied easily higher speed guards in 1992 the pressure on Europe to improve their technology ended. The world was forced to harmonize to weak European Standards and thousands of people; men, women, and children died that did not have to. We speak for millions of victims, we speak for a world that does not get a say whether they live or die. Economically, we are leaders and what we do matters, people will live or die on the decisions we make. After 22 years we are still asking for the same basic safety technology, industry does not have an inherent right to kill to increase profits, cost-benefit is a denial of the people’s right to decide their future, it is a denial of democracy.

Only highlighting perfect victims have cheated us of safety improvements that save all drivers such as underride guards. Media, government, and even safety groups have ignored a majority of trucking victims issues while only presenting perfect victims. FMCSA only allows these perfect victims in their advisory committees encouraging zero coverage of issues important to a vast majority of trucking victims. This must end!

There is a big discussion in the American media about their need for the perfect victim when pursuing stories on public safety issues. We only speak about the positive absolutely righteous cases forgetting that humans are involved, and most of the time we all fall short of perfection. Do we represent a realistic picture and pursue broad based solutions that may save many more people, or do we stick to our unrealistic but very righteous vision. Do we build better underride guards and save everyone, even those imperfect humans who might have made a mistake or do we follow our perfect victim vision and just educate the good drivers and leave those whom we have judged unworthy to their fate. A majority of victims will have some shared responsibility but the fact is it will be cheaper to save them all, in the end we are all human.

The American Trucking Association and other industry associated entities have argued for 50 years to not save trucking victims because they are at fault and not worth saving. The act of not saving victims raised the cost of shipping goods, of insurance, and of healthcare in the U.S. and killed and maimed a large number of children. It delayed the improvements in the crash safety of all motor vehicles. This industry has not only vilified their victims they have never established a charity for those orphaned or maimed by their industry. Trucks and trailers are nothing more than industrial machinery that is exposed to the public and children. The FMCSA to this day refuses to mention underride victims even exist on their website as they are so tied to industry influence and money. The same goes for NHTSA even while they are initiating an underride rulemaking. The rear ends of most cars have more reflective lens material than these industrial trucks and trailers, these victims are bad and not worth saving. Guards save everyone even errant drivers and they save society money. Instead of spending millions lobbying and studying false issues we could have placed guards on most of these trucks and trailers 20 years ago!

See comments from the ATA 1992 Press Release on Guard Rulemaking Below:

“Trucks do not travel down the highway backwards. A truck is rarely at fault in a rear underride collision. Thirty-five to 45 percent of underride victims were under the influence of alcohol at the time of the incident, according to studies by the University of Michigan Transportation Institute.”

FMCSA Should Shift Focus to Crash Causes, Industry Exec Tells Senators

ATA Spokesman: “In addition to issuing the speed-limiter rule, Mullen said, FMCSA should speed up publication of its final rule on electronic logging devices. He also said truck safety efforts should shift in focus from roadside inspection enforcement to what he called “a more effective model centered on on-road traffic enforcement and driver behavior.” There should also be incentives that promote the use of crash avoidance technology on trucks such as lane departure warning systems and forward collision warning systems, Mullen said.FMCSA Should Shift Focus to Crash Causes, Industry Exec Tells Senators”.

The Underride Network agrees with the ATA on speed-limiters, electronic logging devices, and especially on crash avoidance technology! We are aghast at the thought of removing roadside inspections with 20% of trucks with equipment violations mandating being placed out-of-service no longer being inspected.

Three Tragic Crashes Raise Questions About Truck Safety

CCJ Digital has an infographic placing blame on car drivers:

Using data from the DOT, here’s an infographic presenting highlights on fault in fatal truck-car crashes and the main causes. Main Data from the Infographic: Fatality rates for all vehicles have dropped over the past 35 years. For fatal truck-car crashes in 2010, the car crossed the center line 87 percent in head-on collisions. In a rear-end collision, the car hit the truck 76 percent of the time.

American Trucking Associations – Relative Contribution/Fault in Car-Truck Crashes

The preponderance of evidence suggests that car drivers are principally at-fault in about three-quarters (70-75%) of fatal car-truck crashes.

The Federal government spends millions of public money and decades on car driver always at fault propaganda campaign called the No-Zone. All areas surrounding the outside of the truck are forbidden zones and thus any car in a crash with a truck has violated the No-Zone and must be found at fault in any injury or fatality lawsuit. This propaganda campaign in direct partnership with truck lobbying interests stops the government from recommending or regulating blind spot removing mirrors for trucks or proven mirror training such as dots on proper viewing angle of mirrors, probably increasing blind spot crashes. (B.D.S.® Blind Spot Mirror

System – YouTube) (Length-Changeable Side Mirror Apparatus for Vehicles (Trailers, Trucks, Buses) – YouTube) (Car drivers are at fault and not worth saving!) The government in partnership with truck lobbying interests also has law enforcement ride along with truck drivers to find aggressive car drivers and thus teaching law enforcement the victims in crashes they investigate must be at least at partial fault for their own crashes. There is no ride along with dead victims to spot aggressive trucks, there is no partnership with victims safety groups. Public private partnerships are industry, regulator, and law enforcement only with public jobs available to industry insiders and end of career highly paid industry jobs for high level regulators and law enforcement. Millions in campaign contributions and access to millions of truck drivers political clout. Blind Spots on trucks were allowed to exist for 3 decades while cheap remedies existed and thousands died, still unregulated today, new trucks with popular new technology are solving the issue without government regulation. Government No-Zone and Share the Road websites and publications still blame publicly a majority of crashes with trucks on car drivers and still fail to recommend removing blind spots with mirrors and other new technology.

Mirror PicThree side mirror types and a Fresnel lens, all designed to mitigate the
right-side blind spot of a large truck, were viewable by demo attendees
from the driver’s seat of a Boston DPW truck. (VOLPE photo)


YOUTUBE – BLIS – Blind Spot Information System Overview – Volvo S60

YOUTUBE – Subaru Safety Technology – Blind-Spot Detection with Lane Change Assist

2014 Mercedes Benz Truck Changing lanes || Blind spot assist

Letter to Cambridge City Council from Volpe Center on side guards, mirrors and other technology in pdf. London to ban lorries which have no protection for cyclists and pedestrians Will the Feds Step Up for Ped Safety and Close the Crossover Mirror Loophole?

Side Guards Save Lives: A Success Story

January 26, 2015

In this video news story, Volpe engineer Alex Epstein discusses how the implementation of side guards is gaining momentum as a safety feature on large trucks.

Boston City Council passes truck side guard ordinance, first in nation.

GAO report on the No-Zone finds ” Effectiveness of OMCHS Activity to Improve Car Driver Behavior Is Unknown”. The campaign has a goal of reducing fatal crashes involving large trucks and cars by 10 percent over a 5-year period. However, as evidenced by the overall increase in the number of fatalities since 1994, the campaign apparently did not make any progress toward achieving its goal through 1997, the last year for which data are available. OMCHS has not determined to what extent, if any, the “No-Zone” campaign has contributed to changing car drivers’ behavior and reducing crashes between large trucks and cars.

ECE Requirements on Driver’s Vision Updated

LORRY/CYCLIST BLIND SPOT ACCIDENTS – European Cyclists Federation Fitting Blind Spot Mirrors on Heavy Trucks – Europe Consultation Paper London Lorry Control Scheme

Imagine U.S. car drivers arguing there are lots of bad drivers out here so we have to get rid of our bumpers (Underride Guards) and just do bad driver campaigns? Oh Yeah, regulation on bumpers lowered to 2.5 mph, $5000 in damage in very low speed bumps, insurance rates up and car-makers make a fortune selling car parts at inflated prices. Law makers leave this nightmare in place. Consumers pay as much as a third more on car insurance rates, more for car repairs, more for new cars, and the government claims cost benefit? See IIHS reports on this fiasco!

Why bring up all of this negative banter, because the industry lobbyists will be raising these issues in their comments to the standard, the victims are at fault. Unfortunately, the U.S. Government listens to this irrelevant nonsense as they hire industry insiders rather than safety professionals. We will have to form some type of response in our comments to counter these attacks against victims, bullies attack those whom cannot defend themselves and we will have to respond for those thousands of friends and loved ones whom were silenced so violently!

Properly designed crash compatible vehicles when traveling in the same direction and separated from oncoming traffic while traveling at reasonable speeds could conceivably bring a virtual end to most fatal and serious injury accidents. Vision Zero – An ethical approach to safety and mobility teaches us an shared approach to responsibility and solutions in traffic safety is the most efficient way to eliminate serious injuries and fatalities. We must share the responsibility between road users, roadway designers, vehicle designers, and government enforcement and safety programs.

Vision Zero originated to remove the victim blaming approach to safety that was maintaining high death and injury rates. Do you blame distracted pedestrians or add external audible alarms to warn people when a bus driver is turning and permanently solve the problem and save lives. See article link below:

New MTA Victim-Blaming Campaign Is the Opposite of Vision Zero

But in Sweden, where the program originated, there is no victim-blaming component to Vision Zero. Last summer, Claes Tingvall, director of traffic safety for the Swedish Transport Administration, said Vision Zero should involve “moving responsibility upwards” — that is, holding fleet operators, rather than individuals, responsible for street safety. To watch these PSAs, this is the opposite of what the MTA is doing.

Vision Zero shared responsibility and solutions:

All crashes

Crash compatible vehicles

Separated roadways with wide forgiving shoulders Reasonable speed limits

Alcohol, drug, aggressive driving, parking and triangles, fatigue, and texting and mobile phones training and enforcement Rear truck crashes

Enforce Roadside and Off-ramp Parking Regulations, increase rest area parking spaces Enforce Triangle Use, long overdue

Increase conspicuity of trucks with better tape and reflectors, allow brighter fluorescent colors

Enforce weight regulation of dump trucks and decrease massive allowed limits in some states – Slow moving trucks

High speed underride guards, including rounded ends and extension from vehicle

Require vehicle obstruction detection braking or warning systems on all new vehicles, also prevents inattention and fatigue crashes Require lane scanning technology on all new vehicles to guard against side of road crashes and combat fatigue in all types of vehicles

YOUTUBE – Subaru EyeSight®—A Pro Driver’s Opinion Too Many Trucks, Too Little Parking

From the Canadian Rear Guard Standard:

The department’s research also indicated that, for compact and sub-compact vehicles, the requirements of FMVSS 223 were unlikely to prevent underride and passenger compartment intrusion in collisions with speed differentials of 48 km/h (30 mph) or more. According to a study cited by the U.S. Department of Transportation’s National Highway Traffic Safety Administration (NHTSA), the severity of collisions involving underride shifts from non-fatal to fatal at speed differentials of 40 km/h (25 mph) and more, with no fatalities in collisions at relative speeds below 32 km/h (20 mph) and very few in the 32 km/h (20 mph) to 40 km/h (25 mph) range. Graph 1 indicates that collisions involving underride with speed differentials greater than 40 km/h (25 mph) are invariably fatal.

Furthermore, the data cited by the NHTSA indicate that, of the fatal rear- and side-impact collisions involving underride between passenger vehicles and trailers that were analyzed, only 30 percent occurred when the speed differential was 48 km/h (30 mph) or less. An additional 27 percent occurred when the differential was between 48 km/h (30 mph) and 56 km/h (35 mph), while the remaining 43 percent occurred at speed differentials greater than 56 km/h (35 mph). According to these data, the U.S. requirements governing rear impact guards do not address a significant proportion of the fatal collisions involving rear underride that would be survivable based on vehicle design alone.


Graph 1: Relative Distribution of the Incidence of Collisions as a Function of Speed Differential

U.S. underride guard standards as outlined in NHTSA Study

Underride guards on medium and heavy trucks are governed by two standards in the United States. The first standard was issued in 1953 by the Bureau of Motor Carriers, and applied to motor vehicles manufactured after December 31, 1952. This rule applied to straight trucks and trailers and is referred to in this report as the 1953 rule or 1953 standard. The underride guard standard was updated and strengthened in 1998 by a rule that covered trailers and semitrailers. This rule applied to trailers manufactured after January 26, 1998, and is referred to in this report as the 1998 rule or standard. Each rule is discussed in turn.

1953 standard

CFR 393.86 1953 U.S. Rear Guard Regulation for Trucks and Trailers

The 1953 rule applied to both straight trucks and trailers. It required a rear underride guard on vehicles in which the vertical distance from the ground to the cargo bed was greater than 30 inches when the vehicle was empty. Certain vehicle types were exempted, including truck tractors, pole trailers, pulpwood trailers, and trucks in driveaway/towaway operations. In addition, vehicles in which the rear of the tires was less than 24 inches from the end of the cargo body (termed “wheels back”), trucks with cargo beds lower than 30 inches, and trucks with rear-mounted equipment that could provide rear-end protection comparable to a rear underride guard were also exempted. The only strength requirement was that the guard be substantially constructed, and attached by means of bolts or welding. The bottom of the guard must be no more than 30 inches from the ground, within 24 inches of the rear-most extremity of the cargo bed, and must extend within 18 inches of each side of the vehicle. See 49 CFR 393.86(b)(1). As stated, the 1953 rule applied to both straight trucks and trailers. Because the 1998 standard applies only to trailers and semitrailers, the 1953 standard continues to be the controlling rule on rear-impact protection for straight trucks. It also applies to trailers and semitrailers manufactured before January 26, 1998.

1998 standard – Final Rule link below

The underride guard standard was updated for trailers and semitrailers in Federal Motor Vehicle Safety Standard (FMVSS) Nos. 223 and 224. The 1998 standard applies to trailers and semitrailers manufactured after January 26, 1998. The 1998 standard modifies the 1953 standard in three ways. First, the cargo bed height standard was reduced from 30 inches to 22 inches. Second, the wheels back dimension was shortened from 24 inches to 12 inches. And finally, the guard height standard was lowered to 22 inches above the ground. In addition, required underride guard width was increased so that the guard must extend to within four inches of the sides of the truck. The 1998 trailer standard follows the logic of the 1953 standard by exempting certain trailers types, including pole trailers, pulpwood trailers, trailers with horizontal discharge (live-bed), special purpose vehicles, and cargo tank trailers with rear end protection conforming with 49 CFR part 178. Special purpose vehicles exempted are defined as those with work performing equipment mounted at the rear or trailers with loading platforms (e.g., lift gates) that deploy through the space where the underride guard would be mounted. FMVSS No. 223 provides strength and testing requirements and is referred to as the equipment standard and FMVSS No. 224 covers installation and is referred to as the vehicle standard.

49 CFR Part 571 Federal Motor Vehicle Safety Standards Rear Impact Guards; Rear Impact Protection; Final Rule

This final rule establishes two Federal Motor Vehicle Safety Standards (FMVSS) which will operate together to reduce the number of injuries and fatalities resulting from the collision of passenger vehicles with the rear end of heavy trailers and semitrailers. The first standard (FMVSS No. 223, Rear Impact Guards, or the ‘‘equipment standard’’) specifies performance requirements that rear impact guards (guards) must meet before they can be installed on new trailers and semitrailers. It specifies strength requirements, as well as test procedures that NHTSA will use to determine compliance with the standard. The guard may be tested for compliance while mounted to a non-vehicle ‘‘test fixture” or a complete vehicle. The equipment standard also requires the guard manufacturer to provide instructions on the proper installation of the guard. The final rule also specifies requirements to ensure energy absorption by the guards. The second standard (FMVSS No. 224, Rear Impact Protection, or the ‘‘vehicle standard’’) requires that most new trailers and semitrailers with a Gross Vehicle Weight Rating of 4,536 kilograms (kg) (10,000 pounds (lbs)) or more be equipped with a rear impact guard meeting the equipment standard. Requirements for the location of the guard relative to the rear end of the trailer are also specified in the vehicle standard. The vehicle standard further requires that the guard be mounted on the trailer or semitrailer in accordance with the instructions of the guard manufacturer.

DATES: This rule will become effective on January 26, 1998.

Examples and images from NHTSA – The Effectiveness of Underride Guards for Heavy Trailers

FMVSS No. 224 defines the size requirements for the guards (Figure 1), while FMVSS No. 223 describes strength testing and energy absorption requirements for DOT-compliant guards.

The dimensional requirements of the underride guard are the following (Figure 1):

–    Maximum height above ground: 560 mm. (22 inches)

–    Maximum distance from side extremities: 100 mm. (4 inches)

–    Maximum offset from rear plane of trailer: 305 mm. (12 inches)


Fig 1 Config requirement FMVSS 224

Figure 2: Strength test and energy absorption test locations (FMVSS 223)


The energy absorption and strength test requirements are defined at the locations in Figure 2:

– The guard shall resist a force of 50,000 N at points P1 and P2 without deflecting more than 125mm.

– The guard shall resist a force of 100,000 N at point P3 without deflecting more than 125mm.

–    The guard shall absorb an energy of 5,560 J within the first 125mm of deflection at each P3 location.

Currently, NHTSA has granted a petition for a new rulemaking on rear guards with front and side rulemakings pending.


Grant of Petition for Rulemaking at Federal Register

The informal rulemaking process and how to submit comments

The Docket Documents are located at http://www.regulations.gov once there search for the docket number NHTSA-2014-0080 to see documents.

The history of underride guard rule-makings gives us reason to be wary. The Clinton Administration during 85% public approval of stronger guard regulation passed a law that allowed a majority of trucks already on the road to keep the guards they were currently using built to weak TTMA (Truck and Trailer Manufacturer Association) recommendations. The TTMA has already commented on the new proposed rear guard rulemaking that a majority of trucks and trailers already on the road meet the diluted Canadian Standard. The Canadian Standard was weakened by a request from the TTMA that the standard must be harmonized to the weak American Standard to maintain compatibility of shipping between the U.S. and Canada. Years ago the Canadian Standard was an improvement, but technology moves along, current cars can provide the energy absorption to survive centered impacts into a completely stiff guard at 40 mph or more. The Canadian standard is only effective to about 30 mph in offset impacts with a single guard manufacturer tested successfully to 35 mph in offset tests. If we harmonized to the weak Canadian Standard most trucks and trailers will only meet the minimum requirements and we would be stuck for twenty years with an 30 mph standard that protects only 30% of victims (NHTSA: “Without doubt, the great majority of these serious injuries occur above 30 mph, especially when one acknowledges the fact that two-thirds of all rear impact closing speeds are judged to exceed 30 mph.’1 2 3 4 5 6). We need a modern high speed Standard for trucks that is compatible with current car safety technology (40 mph in centered impacts) and future car crash performance including energy efficient size and weight and body material of future fleets, one that will serve us for 20 years or more. We will have to live or die with this Standard for decades.

Summary of U.S. & Canadian Guard Requirements

U.S. Canadian
FMVSS 223/224 CMVSS 223
Guard Height 560 mm before test 560 mm after test
Strength Requirements 50 kN at P1 50 kN at P1
50 kN at P2 50 kN at P2
100 kN at P3 350 kN Uniform Load Test
Energy Absorption 5,650 Joules 20,000 Joules

Newer underride guard designs have the possibility to protect vehicles in higher speed crashes. MUARC tested guards to 75 km/h (47mph) in the early 1990‘s. Governments need to begin crash testing new designs and find those capable of better speed performance and determine the distance from the front and back of trucks or trailers to extend guards for improved high speed performance. The ends of extended guards (800mm for 90 km/h) could be rounded to deflect vehicles at very high speeds. Truck size and weight length limitations will need to be adjusted to accommodate the new guards length. “The size of an energy-absorbing truck front structure directly correlates to the survivable closing speed between car and truck in head-on collisions (e.g. 75 km/h survivable closing speed requires a 400 mm long energy-absorbing structure, 90 km/h, requires 800 mm).” From Volvo Report.

NHTSA in 1991 stated “Rear impacts involving underride, which are virtually all PCI (Passenger Compartment Intrusion), have the highest severe injury rate, from 25-28 percent of all injuries sustained in rear end crashes. Without doubt, the great majority of these serious injuries occur above 30 mph, especially when one acknowledges the fact that two-thirds of all rear impact closing speeds are judged to exceed 30 mph. It is not surprising that severe injury production would be inordinately high in rear impacts by passenger cars given the statistical anomaly that over 50% of combination truck rear underride crashes by passenger vehicles occurred with big rigs that were stopped on the shoulders of high speed highways.” The current U.S. guard standards were acknowledged to be effective to 27 mph, a 40 mph standard was acknowledged to be feasible, but was overruled as not cost-effective due to a 40% higher cost for the stronger guards. Modern cars can survive a 35 mph impact into a stiff wall but an impact with current U.S. underride guards above 25 mph can often be fatal.

In order to save a majority of victims a guard standard will have to approach 50 mph as a bare minimum target. We will have to extend the guard out from the truck to incorporate increased crush zones of 800mm or more. We will have to round the ends to deflect vehicles in very high speed crashes.

APROSYS: “The safety proposals presented by APROSYS SP2 have been shown to have considerable casualty reduction potential but would be difficult to achieve within current length limits without losses in payload and productivity.”Also “if concessions were permitted within vehicle weights and dimensions legislation to promote integrated designs then the casualty savings could be achieved along with a reduced environmental footprint and no effect on payload, productivity or congestion.”

NHTSA stated: “Overall, the mean relative velocity at impact was estimated at 44.0 mph. About 32 percent of the impacts occurred at relative velocities less than 35 mph, and in 43 percent, the relative velocity was 40 mph or less. However, many impacts were at very high relative velocities, and probably not survivable. In over 25 percent of the cases, relative velocity was over 55 mph and in 13 percent it was more than 60 mph.”

VC-COMPAT: “Plans are underway to extend the front of the truck 300mm to 500mm or more to create a crash zone or defonmable soft nose that would absorb crash energy and might reduce serious injuries and fatalities another 10% from the current standard on trucks with energy-absorbing guards, and survivable speeds would be increased to 80-90kph.”

The Underride Network supports recommendations made by IIHS to improve U.S. Rear Guard regulations. IIHS provides analyses and test results showing that NHTSA could greatly reduce the likelihood of rear truck underride by reopening rulemaking on FMVSS 223 and 224 to:

On guard: Safety gear on the back of truck trailers is improving

IIHS recognizes for American crashes Canadian standard will need to be exceeded, unfortunately still running low speed guard tests which are improving American guards (Which is excellent) but are less than overseas crash test standards of nearly a decade ago. Impact project crash tests at 40 mph offset in Brazil and MUARC 47 mph full frontal in Australia. IIHS says: “IIHS trailer crash tests have demonstrated that underride guards need to be stronger than current U.S. safety standards — and in some cases exceed tougher Canadian rules — in order to prevent underride in the kinds of crashes that happen on North American highways”.

Heavy Goods Vehicle Under Run Protection – Federation Internationale de I’Automobile in PDF Requirements for effective HGV Underrun Protection

“A rear underrun protection system is the rear “bumper” of an HGV (Heavy Goods Vehicle)”

“It is designed to prevent the impacting vehicle from getting wedged under the HGV”

“It is designed to cause the crumple zone of the impacting car to absorb energy”

NHTSA Definitions:

Underride: When a passenger vehicle collides with the rear end of a trailer or semitrailer and the front end of the passenger vehicle slides under (i.e., underrides) the rear end of the trailer. Underride occurs to some extent in most collisions in which a passenger vehicle crashes into the rear end of a large trailer because most trailer beds are higher than the hoods of passenger vehicles.

Passenger Compartment Intrusion (PCI): In Passenger Compartment Intrusion or ‘‘excessive underride” crashes, the passenger vehicle underrides so far that the rear end of the trailer strikes and enters its passenger compartment. PCI collisions generally result in passenger vehicle occupant injuries and fatalities caused by occupant contact with the rear end of the trailer.

Energy Absorption in guards: Overly rigid guards may stop the passenger vehicle too suddenly, resulting in excessive occupant compartment deceleration forces and killing or injuring passenger vehicle occupants.

Wikipedia Definition of Crumple Zones – Crumple zones work by managing crash energy, absorbing it within the outer parts of the vehicle, rather than being directly transmitted to the occupants, while also preventing intrusion into or deformation of the passenger cabin. This better protects car occupants against injury. This is achieved by controlled weakening of sacrificial outer parts of the car, while strengthening and increasing the rigidity of the inner part of the body of the car, making the passenger cabin into a ‘safety cell’, by using more reinforcing beams and higher strength steels. Impact energy that does reach the ‘safety cell’ is spread over as wide an area as possible to reduce its deformation.

Semi-Trailer Truck at Wikipedia – A semi-trailer truck is a large vehicle that consists of a towing engine, known as a tractor in the United States and truck in many other places, attached to one or more semi-trailers to carry freight. It is also known as a transport (truck) in Canada; semi or single in Australia; semi, tractor-trailer, big rig, or eighteen-wheeler in the United States; articulated lorry, abbreviated artic, in Britain and Ireland; and “lorry” in Malawi.

TIP: Smaller single-unit trucks are only required to install the old style guillotine guards which are mounted 30 inches from the ground, these dangerous trucks which are involved in a large number of rear end crashes must be included in the new standard.


Guillotine Guard Pic1953 style guillotine guard


NTSB Recommends Changes To Enhance the Safety of Single-Unit Trucks

NTSB Safety Study Synopsis: Crashes Involving Single-Unit Trucks that Resulted in Injuries and Deaths

NTSB: “Although single-unit truck crashes are neither as lethal nor as likely to cause the most severe injuries as compared with tractor-trailer crashes, available data show that they are involved in at least 37 percent of the fatalities, 49 percent of inpatient hospitalizations, and 61 percent of emergency department visits from large truck crashes.”

NTSB: “Twice as many pedestrians and cyclists received non-fatal injuries in single-unit truck crashes as in tractor-trailer crashes, although the numbers of fatally injured pedestrians and cyclists were 19 percent lower in single-unit truck crashes than in tractor-trailer crashes.”

NTSB: “The fatalities and serious injuries that are caused by rear underrides, which occur in most collisions resulting in injury between passenger vehicles and the rears of single-unit trucks, could be mitigated by well-designed rear underride protection systems.”

TIP: Wheels back trailers are now exempt from guard standards but modern cars require a flat surface to interact with their safety systems. Tires are hard surfaces and present an uneven surface hazard that can be mitigated with the flat surface and proper height and energy absorbing features of an properly designed underride guard. NHTSA Study: “Wide-base singles may become more widespread to improve the fuel economy of the truck population. Wide-base singles present a larger gap for smaller, narrower light vehicles, which in turn brings the wheels-back exemption into question.”

TIP: Guards can break off of trailers during a crash due to the massive force involved. Attachment hardware such as bolts must be extra thick and strong, attachment points such as the trailer frame must also withstand tremendous forces and if not strong enough the trailer frame should be required to be reinforced in the standard. Guards should be tested on the trailer so attachment failure which is common can be decreased.

TIP: Offset crashes can kill in even a few inches of overlap with the trailer. It is common to have guards not extend to the outside edges of the trailer, when the car hits just a few inches from the outside edge it can completely miss the outside edge of the guard and at a slight angle can underride the trailer up to five feet until it contacts tires with catastrophic results. These offset from center crashes are quite common and the force of the impact can be concentrated in the outside inches of the guard away from the reinforcing struts that hold the guard bar to the trailer. It is important to have the guard extend all of the way to the edge of the trailer with angled high strength reinforcing struts close to the ends of the guard, probably not more than 6 to 8 inches from the trailer edge. Moving the P1 force test location further out to the edge of the guard such as IIHS recommends will help to guarantee the ends of the guard are strong for these offset crashes. We must require better bracing than vertical struts provide!

MUARC Guard PicMUARC Guard Design strong energy absorbing struts are placed at outside edge of guard


TIP: The guard bottom must be close to the road to align at the height of most car bumpers, around 400 mm or 16 inches. The bumper must be engaged to properly interact with car safety features such as crush zones which are designed to absorb crash energy. If the guard is not low enough the car can penetrate below the guard and create the wedge effect (See Below) lifting the trailer causing crush zone features of the car to not engage and sending the hard bottom edge of the trailer towards the windshield and car occupants.

TIP: We can only have a new rear guard rulemaking every twenty years or so, if a thousand extra people die a year that can add up to twenty thousand lost lives. NHTSA: About 32 percent of the impacts occurred at relative velocities less than 35 mph, and in 43 percent, the relative velocity was 40 mph or less. Do we only deal with 43% of the crashes with a 40 mph standard or do we use 20 plus year old technology ( MUARC tested guards to 75 km/h or 47mph in the early 1990’s.) and try for an higher speed standard and save many more lives? I think we know what we must do!

TIP: Truck and trailer manufacturers must only meet the minimum requirements when building guards, there is no longer a strong strict liability legal deterrent to using old technology that is proven to kill. Errant victims and their passengers are even losing the right to sue, there is no shared legal liability for a company that knowingly uses guards that kill at 25mph. If a large trailer manufacturer uses technology that year after year kills an extra 100 people there is no cost, they only profit by using the nominally cheaper technology. There is no moral or financial impetus to exceed the minimum standards, we must understand the minimum standard will be the highest standard that will occur in society and act with this knowledge in mind. Law enforcement spends millions to educate errant drivers but nothing to encourage using better safety technology when it comes to underride guards.

TIP: Heavy trucks and trailers are industrial equipment that is operated in the public domain. You would not place a table saw without blade guards where children would have exposure to it, yet we operate industrial trucks and trailers without guards or working guards in public exposing families to daily danger of death and disability.

TIP: Underride guards placed even with the back of the truck or trailer will impact the front of short or no-nosed vehicles at the same time as the stiff rear metal tray of the trailer. Extending guards out from the back of the trailer is the only way to provide protection for Euro-styled trucks, vans, and minivans, and ultra mini cars.

TIP: In 2012, large trucks were more than three times more likely than other vehicles to be struck in the rear in two-vehicle fatal crashes. 19% of all fatal two vehicle truck crashes occurred to the rear of the truck.

TIP: Point of impact rear of truck statistics 2011: Fatalities Rear 586 16.2% Injuries Rear 14,000 22.1% Property Damage Only Rear 55,000 24.6%

TIP: In Europe folding rear guards for single-unit and trailer dump trucks are available, they automatically tilt or fold when dumping and can even be smart phone controlled. There is no excuse to allow government and industry in the U.S. to refuse to require modern style rear underride guards on dangerous dump trucks and coal trucks. See SKI link and BMI Tarmac link below:

Reading Material:

Improved Crashworthy Designs for Truck Underride Guards in PDF


NHTSA- Heavy-Vehicle Crash Data Collection And Analysis to Characterize Rear and Side Underride and Front Override in Fatal Truck Crashes

Analysis of Rear Underride in Fatal Truck Crashes

The Impact Project – The Wedge Effect

American Standards Rear Guards: Comments

The Impact Project: Estimating Forces During Collision

IIHS: Underride guards on big rigs often fail in crashes; Institute petitions government for new standard IIHS Status Report: Crash tests demonstrate the need for new underride guard standards Canada Safety Council – Canada Loosens Bumper Standard to Align with U.S.

Transport Canada: Rear Impact Protection a Canadian View in pdf

SKI-Innovation-Booklet: Smart Phone Controlled Automatic Folding Underride Guard for Tipper Trucks and Trailers

Impact Project – Pliers Underride Guard Design and Crash Tests

Buses getting rear ended Youtube Video

Bmi Tarmac walking floor hydraulic rear under run

EU ADAC Crashtest on Youtube: Rear underrun protection systems of heavy goods vehicles


NYC Begins Installing Truck Sideguards To Protect Pedestrians And Cyclists


Student thesis simulations of the Pliers Design show zero intrusion at speeds of 50 mph. See evaluation link above.

NHTSA must test or contract tests at higher speeds (at or above 50 mph) of new innovative guard designs including deflecting cars at high speeds to investigate hazards of deflection of cars with other traffic. We must measure effects of extending guards with new energy absorbing materials. We will never see achievable high speed guards without government testing, industry will not push for higher speed regulation. We can save them if we, NHTSA for U.S. citizens, try!

Other Safety sites and Orgs for further research:

Truck Safety Coalition

Insurance Institute for Highway Safety IIHS

Advocates for Highway and Auto Safety

UNICAMP Impact Project


AnnaLeah & Mary Karth Truck Safety Petition Byron Bloch at autosafetyexpert.com

The Underride Network supports a high speed standard such as recommendations from MUARC in Australia would present.


1.    Barrier test Forces:

P1 (outer edge)   P2 (off centre)   P3 (centre)

              200 kN          200 kN          100 kN

2.    Barrier height: 400mm

3.    Barrier width: Within 100mm of the outer frame of the rear of the truck

4.    Energy absorption: 50kJ minimum

Video 4a Energy absorbing underrun barrier crash test with rear of truck, 75km/h, Monash Univ. Video 4b Energy absorbing underrun barrier crash test with rear of truck, 75km/h, Monash Univ.

NHTSA: “It is not surprising that severe injury production would be inordinately high in rear impacts by passenger cars given the statistical anomaly that over 50% of combination truck rear underride crashes by passenger vehicles occurred with big rigs that were stopped on the shoulders of high speed highways.” Truckers properly placing triangles on the roadway could prevent many of these crashes, likewise higher candlepower fluorescent tape colors could also prevent many rear end crashes. Driver reaction time is critical and increasing visibility of trucks provides this precious extra time to perceive and react to the danger ahead. Drivers have a right to this warning of slow or stopped obstructions of the roadway or shoulder.


Coal Truck PicUnsafe Parked Trucks – Please use triangles to save lives and give drivers warning!

Kentucky single-unit coal truck with poor guard and poor visibility or conspicuity.

Emergency triangles placement video by ATA Assoc. on Youtube

New recommendation: The Underride Network will be supporting automatic lighting to prevent most rear underride crashes.

In reading an old 1991 MUARC  study it was recommended to install slow or stopped automatic lighting for trucks. Imagine speed controlled flashing lights at the top edge of the trailer or incorporated into brake lights that would flash whenever speed reduces to 35 mph or below including when stopped? Modern computer control should make this a simple and low-cost fix as new truck designs include fancy LED lighting systems. We need safety training for truck drivers to flash flashers when slowing on hills or when stopping and slowing for traffic congestion and road repair.



NHTSA Study: ” A study by Minahan and O’Day of fatal car-truck accidents in Michigan and Texas found evidence of underride in 90 percent of rear-end impacts and 70 percent of side impacts. Underride was found typically to occur at night on straight rural roads. Impact speeds were generally greater than 30 mph. The authors characterized this type of crash as a “surprise event” in which a passenger vehicle came upon a slower or stopped truck unexpectedly.”

Where is the national use triangles to save lives campaign FMCSA? The prior truck safety regulatory agency “The Federal Highway Administration” (FHWA) ran annual campaigns to promote safe parking of trucks. Underride Network and CRASH volunteers pressured the federal government to form an agency to concentrate on truck safety as the highway agency was not chartered for or able to do. We now have zero national safe parking campaigns, no triangle use campaigns, no underride victim liaison or victim centered campaigns, and no use better underride guard technology campaigns or education efforts. Remember NHTSA stated “over 50% of combination truck rear underride crashes by passenger vehicles occurred with big rigs that were stopped on the shoulders of high speed highways” so rear underride involves triangles and parking safety. Maybe, we need to revisit the FHWA taking over truck safety again, the FMCSA has been a disaster from the lack of public education efforts on critical truck safety issues. As we look at regulating future rear underride guards we must also improve and increase our efforts at public safety campaigns and research into related issues, such as improving the rear conspicuity of trucks and trailers with fluorescent colors of reflective tape.

Years ago, the Underride Network participated in an national news story on underride guards. The report looked at the issue of dump trucks and specifically single-unit coal trucks which were exempted from the regulation. These heavy several ton trucks must only use the 1953 ICC bumper we call guillotine guards, 30 inches from the road and firmly attached. The reporter from the news story walked to the rear of one of the coal trucks and gave the guard a swing. It swung back and forth like a child’s swing. He asked the truck driver if the underride guard should behave that way? The truck driver asked “What is an underride guard”?

Single-unit trucks such as dump trucks can be extremely heavy due to hauling heavier loads than most big rigs do. This can slow them down when climbing hills or getting up to speed. They usually due to dirt and road film have poor conspicuity or visibility and combined with useless underride guards this can all add up to disaster. We need public education campaigns on guards and conspicuity safety such as proper care and cleaning of tape and reflectors. We need government testing and design of specialty guards, such as high speed rounded ends to deflect cars and guard designs to work with specialty rear ends like dump trucks. Automatic articulating guards with smart phone control as an example, government can promote technology that improves safety and encourage economic growth as an added benefit. Truck drivers and companies can learn the benefits of guard technology, learn about victims, and understand cost savings from accidents and insurance savings. Insurance companies can be encouraged to pass along cost savings. We can save an estimated $1.76 for every dollar spent on guard technology by regulating guards on single-unit trucks using UGPTI cost and benefit estimates from article link below.

Today we have the advantage of light weight high strength metal alloys, guards are no longer gas robbing heavy behemoths. We have 20 years of history of low guards not obstructing the trucks travel, railroad crossings have been redesigned as have many loading docks. We just need the space (long energy-absorbing structure) to decelerate the higher speed vehicles in crashes, we need to exempt trucks length restrictions to allow longer high speed guards. We need our government to promote the use of guards that exceed minimum standards, they must highlight lives saved and reduced costs such as insurance rates. The trucking industry have spent years railing against better guards, only the government has the funds to turn around drivers negative views of effective safety equipment. Using it does not make you a bad driver, using it makes you a caring driver.

This is 2014! We need an high speed standard to ultimately save many thousands of lives and serious injuries as other countries adopt the new standard. Guards are wonderful technology, they save everyone even errant drivers.

Rear Guard Regulations and Recommendations:

Rear Underrun Protection Devices | UN Regulation No. 58 – GlobalAutoRegs

Brazilian underride guard regulation that correctly exceeds unsafe U.S. and European Standards

The Canadian Rear Guard Regulation

Canadian rear underride guard tests and recommendations in PDF format.

Penn State simulated car-truck crashes with varying guard heights

Australia – MUARC Monash University Accident Research Center – Review of Truck Safety and Older Recommendations UGPTI: Underride: Do Rear Impact Guards Help?

Articles and length Regulations that would require amendment for modern underride guards:

U.S. Federal Size Regulations for Commercial Motor Vehicles


Commercial Motor Vehicle Size and Weight Enforcement in Europe

http://www.theicct.org/sites/default/files/publications/ICCTupdate_EU_HDVconfigurations_Jun2013.pdf EU lawmakers vote for redesign to make trucks safer and greener

Parliament approves safer trucks

EU truck safety and efficiency law faces delay until 2019

Upper Great Plains Transportation Institute at NDSU: “Cost-benefit analysis shows that the rear-guard safety equipment has injury severity benefits that far outweigh equipment cost. Given a 10 percent reduction in injury severity attributed to the rear-guard devices on agricultural trucks, in the relevant crash population, the benefit is esti-mated to be $14.4 million over the seven-year depreciable life of a truck. Total equipment and maintenance cost for the North Dakota agricultural truck fleet is estimated to be $8.1 million. An estimated safety benefit of $1.76 is generated from each dollar spent on rear guards for North Dakota’s agricultural truck fleet.”

Delay and environmental costs of truck crashes

This report presents estimates of certain categories of costs of truck- and bus-involved crashes. Crash related costs estimated as part of this study include vehicle delay costs, emission costs, and fuel consumption costs. In addition, this report also develops improved methods for estimating property damage costs and presents the results of that improved methodology used on updated data. Finally, the report presents costs specific to crashes involving hazardous material (HM) releases. The development of each of these costs, including underlying assumptions, model framework and methodology, and data analysis, is discussed in detail. http://ntlsearch.bts.gov/tris/record/ntl/48200.html

National Research Council Canada: Side Guards for Trucks and Trailers Phase 1: Background Investigation (Other types of rear of trailer coming length exemptions)

“Boat tails are devices that are fitted to the rear of van semi-trailers. These devices shed vortices as they leave the trailing edge of the trailer hence reducing aerodynamic drag and are designed to minimize any interference with operations. Tests performed at Clarkson University have shown that boat tails can reduce trailer drag by as much as 9% and fuel consumption between 4% and 8%. Boat tails increase the effective length of a trailer therefore they are typically only mounted to 48 foot trailers. However, some jurisdictions do allow two foot boat tails on the more common 53 foot semi trailers.”

Transport Canada: Review of Aerodynamic Drag Reduction Devices for Heavy Trucks and Buses Boat tails/extension panels

Tapering the back end of a long vehicle will increase its base pressure by providing pressure-recovery of the surrounding flow before it leaves the sharp back edges and forms a wake. This increased base pressure provides a lowered overall pressure difference from front-to-back of the tractor-trailer combination. Boat-tails, otherwise known as extension panels, is another technology that has been demonstrated to be effective to reduce the drag of tractor-trailer combinations, although various configurations are available (see examples in Figure 19).


Boat Tail PicFigure 19 Boat Tail Concepts


Notice about 5 feet of extended rear guard due to extended boat tail! Large majorities of Americans in polling oppose any increase in truck length which probably would change if they were told the whole truth. Manufacturers are not going to reduce cargo capacity to achieve extra length to the rear of trucks and trailers. We need a length exemption for underride guard technology to compensate for extended underride guards.

During the 20 years of the new rear guard rulemaking new trailers will have tapered extensions and be curved under at the rear like a boat, this will impact underride guards and their designs and must be incorporated in any new rule.

VC-COMPAT – Vehicle Crash Compatibility Project in EC 5th Framework Programme

Results from VC-COMPAT Project show underride deaths can be reduced!

The analysis revealed that about 11 % of the fatally and 30 % of the seriously injured car occupants could be saved if trucks were equipped with energy absorbing front underrun protection systems (e.a. FUPS) instead of rigid FUPS, and that approximately 57 % of the fatalities and 67 % of seriously injured could be prevented from their injures due to improved rear underrun protection systems (RUPS). The report closes up with the major conclusion that improving rear underrun protection systems show a comparable reduction potential as for improving front underrun protection systems.


VC-Compat Final Technical Report.pdf

Final publishable technical report VC-COMPAT (1.7Mb)


VC-Compat Improved Rear Underride Guard Costs in EU

Current RUP devices cost 100 € – 200 € (Approx. $134 – $268) per vehicle. Additional costs ranging from 20 € to 100 € (Approx. $27 to $134) are estimated for ‘low profile’ improved RUP, while additional costs for more complex folding devices may exceed 200 € (Approx. $268) per vehicle.

VC-Compat: “the energy absorbing capability and capacity of passenger car front structures has improved to such an extend that impact speeds up to 64 – 75 km/h (Approx. 40 mph to 47 mph) may well be survivable for passenger car occupants in collision with rigid FUPs.“


The findings from this crash test program (and the theoretical calculations presented) highlight some unnecessary inadequacies in the performance

requirement set out in various international standards. These inadequacies will lead to predictable failure of the barriers to prevent underride even at moderate speeds.

Table 6. Comparison of international force performance requirement for underride barriers,and proposed values

Load               E.C.E  R 58                      USA                        Brazil              Recommended
position           maximum           (FMVSS  223/224)                                     (this study)

                                                       Test Load kN

OuterP1 25
Off centre P2 100 100 150 200
CentreP3 25 50 100 100

Table 6 compares the various international standards with those proposed from this study. Both the ECE and USA test load values for offset impacts (outer edge) are too low, and will not prevent underride in even low speed impacts. As the ECE load requirements are further reduced for lower mass trucks, these values are even less valid and quite ineffective in terms of underride protection. The recommended force requirements should be applicable for all heavy vehicles with little reduction for lower mass ranges.

The load requirements set out for Brazil in Table 6 are far more realistic. These are based on the extensive work done at Unicamp University in Brazil on improved underride design under the Impact Project [5]. The reader is referred to the excellent Unicamp website at www.fem.unicamp.br/~impact.) It is noted that the ‘Recommended’ forces in Table 6 are increased in some cases from our earlier studies [4, 7, 8, 10]. This is based on the need to allow for higher impact speeds (around 75km/h), and a more realistic recognition of the load capacity needed for offset impacts. It also recognizes that such performance criteria are achievable and practical for the trucking industry.

On a practical note (to emphasis this latter point), small section, lightweight steel struts, such as rolled rectangular steel sections of 75mm*50mm*3mm, are sufficient to resist compression loads of 200kN. These sections only weigh 5.43kg/m.


1.    Barrier test Forces:

P1(outer edge)   P2 (off centre)    P3 (centre)

         200 kN             200 kN             100 kN

2.    Barrier height: 400mm

3.    Barrier width: Within 100mm of the outer frame of the rear of the truck

4.    Energy absorption: 50kJ minimum

We have tried to provide a very wide coverage of safety issues beyond just rear guard specific issues including industry and government placing blame on car drivers and underride victims. Many in the industry have claimed that safety advocates and victims are not knowledgeable enough to comment on trucking safety issues and should be banned from this freedom of speech expression. We believe if you browse the resources presented here your ability to provide an intelligent appraisal of all rear underride guard safety issues will be unmatched by any industry anti-guard and anti-safety commenters.



IIHS Petition for Guard Rulemaking Recommendations:

1   Substantially increase the quasi-static force requirements

2   Move the P1 test location farther outboard to improve offset crash protection;

3   Require that attachment hardware remains intact throughout the tests;

4   Require guards be certified while attached to the trailers for which they are designed;

5   Investigate whether the maximum guard ground clearance can be reduced; and

6   Reduce the number of exempt truck and trailer types.

IIHS petition_rear guards_2011 -02-28 in PDF

IIHS: Modern car designs can effectively “absorb the energy of a 56 km/h (35 mph) full-width rigid wail impact and a 64 km/h (40 mph) deformable barrier crash with 40 percent overlap”.



“Research into rear underrun crashes has shown that an underrun barrier needs to absorb a minimum of 50 kJ, though preferably the energy dissipation should be 100 kJ.”

“A final crash test at 75 km/hr was carried out at Melbourne’s Autoliv facility, once again with passenger and driver crash test dummies as shown in Figure 12. The mass of the vehicle in this instance was around 1350 kg. The energy dissipated by the barrier was 50 kilojoules over a distance of 300 mm. Barrier forces of the order of 500 kN were measured. The comparison of the Hybrid III results at 75 km/h with the equivalent 56km/h NCAP full frontal barrier test, indicates that the energy absorbing system reduced the crash severity for the front passenger (HIC of 1205 vs 1223; chest deceleration of 48 g) to that of a 56km/h impact. For the driver the impact was a little more severe than the NCAP test (HIC 1842 vs 1499; chest deceleration of 56 g; high femur load of 14kN).”

U.N. Comment: (Increasing energy absorption reduces the strain on trailer frames and mounting hardware for high-speed crashes. High-speed crashes require high energy absorption (imagine bigger pillow) to decrease deceleration forces on car passengers i.e. a bigger pillow allows surviving higher speed crashes!)



NHTSA’s proposed guard height at 22 inches from the roadway will kill in tests at higher speeds. Testing at low-speeds misrepresents the safety of higher guard heights and road tests prove lower guard heights are safe and feasible. A guard bottoming out would be rare and cheap to fix, why change our entire safety philosophy for a rare problem that does not really exist as American trailers average guard height is 18 inches.

Australian Postal truck 4 years MUARC Guard
(MUARC Guard 4 year road test at 450mm from roadway). The rear overhang was 3.5m. The clearance of the rear of the barrier from the road surface was set at 450mm. Condition of the barrier after 4 years: the Australia Post truck with the energy absorbing rear underrun barrier, photo taken on October 18th 2002, some 4 years after fitting.


Underride Network position on high-speed crash tests:

NHTSA crash tests new cars to rate their safety in crashes and publishes performance based on a star system thru their NCAP rating for new cars.  You might buy a car that is 5 star crash rated that passed with flying colors the 35 mph offset crash test. Why are trucks exempted? Undo influence from lobbyists?

When we crash test guards at 30 to 35 mph we get guards for 50 years that perform at 30 to 35 mph. When you try something over and over and over again and get a negative result, why would you continue this activity. If we crash test guards at high speeds perhaps we will see guards that perform at high speeds. The FHWA tests crash attenuators in 62.2 mph crash tests (Real World Crash Speeds) and attenuators protect cars and trucks in crashes at 62.2 mph and more!

The FHWA Office of Safety considers that a 100 km/h (62.2 mph) crash test is representative of worst case run-off-road crashes. We agree, real world fatal crashes happen on 50 mph roadways and between 50 and 60 mph. If we test at real world crash speeds we will get underride protection that performs at these speeds. When guards fail tests at real world speeds manufacturers will finally feel public and political pressure to increase crash effectiveness. We must see real world tests of guards at 50 and 62.2 mph such as tests at FHWA for crash attenuators. We must use more extensive crash test criteria such as those used in the AASHTO Manual for Assessing Safety Hardware (MASH). MASH tests cars to 100 km/h or 62.2 mph and big trucks at 80 km/h or 50 mph. MASH tests crash attenuators at various speeds and we should do the same for underride guards to give the public a real world picture of their safety.

The Underride Network supports a similar criteria for underride guard crash tests as those submitted by Prof. Raphael Grzebieta and (Adj) Associate Professor George Rechnitzer and Transport and Road Safety (TARS) Research Centre in Australia based on the criteria used for MASH crash tests in the AASHTO Manual. We would submit requiring multiple speed tests to include real world crash speeds and would not limit extension of guards to increase crush or stroke distance to increase guards effective speed while diminishing deceleration forces. Tests might be performed at 44 mph and 50 mph and 62.2 mph to test minimally compliant guards in low-speed test and using higher speed tests to monitor performance at real world crash speeds. We support testing for Practical Worst Case (PWC) scenario crashes that happen in the real world just as MASH includes PWC in it’s crash test series. We must include tests of offset controlled after crash direction of vehicle spin or VRU (Vulnerable Road User or bikes and pedestrians) after crash spin to assess high-speed crash avoidance for cars and prevention of running over VRU users in frontal crashes. John E. Tomassoni “It is expected that certain offset conditions could result in car rotation such that the passenger compartment may beneficially avoid intrusion entirely”. WE would encourage annual NCAP type testing of truck and trailer underride guards to encourage industry improvement of guards on an annual basis such as crash performance of cars improves on an annual basis using publication of the results of NCAP tests for cars to increase sales of better performing products.


Chalmers Car-to-Truck Frontal Crash Compatibility

Increasing the length of the HC (HoneyComb shaped front nose underrun guard) increases the critical impact speed

To 95 km/h (59 mph) with a 300 mm – length HC structure (+27%)
To 102 km/h (63 mph) with a 600 mm – length HC structure (+36%)
To 107 km/h (67 mph) with a 900 mm – length HC structure (+43%)


Copyright 2014 by Underride Network