In a comment on a recent article about former President Jimmy Carter and his health, Louis Lombardo thanked him for his impact on road safety:
Comment by Louis V. Lombardo, Bethesda, MD 6 hours ago
“Among the great things President Carter did was to appoint Joan Claybrook to head the National Highway Traffic Safety Administration (NHTSA). As a result several hundred thousand lives have been saved in the U.S.A. by vehicle safety technologies and policies.
This was accomplished despite the facts that President Reagan 1, appointed a coal industry lobbyist to replace Claybrook, 2, rescinded the airbag regulations, and 3, cut NHTSA by 33% i.e., 300 safety workers.
The pdf to which Lombardo provided a link, Lives Saved by Vehicle Safety Technologies and Associated Federal Motor Vehicle Safety Standards, 1960 to 2012 Passenger Cars and LTVs (January 2015), is a lengthy analysis of the Lives Saved by various safety standards and technologies over the years. (FMVSS = Federal Motor Vehicle Safety Standards).
Along with 24 other safety standards–reviewed for their effectiveness in reducing fatalities, injuries, and crashes for passenger cars and LTVs–on p. 214-216, there is a discussion of Underride Guards, although there is no reference to research which shows that stronger guards can be manufactured–giving the potential for increasing the number of Lives Saved by improving FMVSS 223 & 224 (Rear Impact Guards/Protection on Heavy Trailers):
“FMVSS No. 223, ‘Rear impact guards for heavy trailers’ FMVSS No. 224, ‘Rear impact protection for heavy trailers’
These two standards regulate one safety technology for heavy trailers with GVWR over 10,000 pounds that has been partially evaluated by NHTSA and that is primarily designed to protect the occupants of cars and LTVs that collide with the rear of the trailers:
• Underride guards for heavy trailers
The bodies of heavy trailers usually ride fairly high above the ground. The front ends of LTVs and especially passenger cars are relatively low. When the front of a car or LTV hits the rear of a trailer, there is a risk that the car’s hood will underride the trailer, with little structural engagement. The trailer can intrude into the passenger compartment of the car or LTV, with great danger to the occupants. The underride guard is attached to the rear of the trailer and extends below the body of the trailer. It is designed to engage the hood of the car or LTV and prevent underride. Ideally, the underride guard should extend low enough to engage even small cars, be wide enough to catch impacts near the corners of the trailer, and be strong enough to not fold or break out of the way upon impact.
History: NHTSA issued FMVSS Nos. 223 and 224 in January 1996. FMVSS No. 223 specifies the height, width, length, and strength requirements for rear impact guards for trailers and semitrailers; FMVSS No. 224 establishes requirements for the installation of rear-impact guards on trailers and semi-trailers with GVWR of 10,000 pounds or more manufactured on or after January 24, 1998. FMVSS Nos. 223 and 224 do not apply to pole trailers, pulpwood trailers, lowchassis vehicles, special purpose vehicles, “wheels back” vehicles, or temporary living quarters – generally because these vehicles ride closer to the ground than van-type trailers or because the “wheels back” feature prevents underride from occurring, since striking vehicles contact those wheels and do not underride the back of the vehicle.513
However, the Truck Trailer Manufacturers Association (TTMA) had already issued a voluntary Recommended Practice RP 92-94 in April 1994 that included all the essential elements of the subsequent NHTSA standards except for the energy absorption requirement. Subsequently, Transport Canada issued CMVSS No. 223, “Rear impact guards,” effective in 2005, which not only encompasses FMVSS Nos. 223 and 224 but also sets somewhat higher strength requirements than those FMVSS.514 Before 1998, trailers and semi-trailers were Federally regulated by Federal Motor Carrier Safety Regulations (FMCSR) that incorporated specifications for rear impact guards developed by the Interstate Commerce Commission in 1952.515 The ICC guards were substantially narrower and smaller than those required by the current NHTSA standard and the TTMA recommended practice. The ICC guards were not required to meet strength tests.
In other words, there are five generations of underride guards: (1) The original state of no guards at all, which had ended by 1952; (2) The narrow ICC/FMCSR guard from 1952 to approximately 1994; (3) A transition circa 1994 to the TTMA guard which has the dimensions of current guards but not necessarily their strength; (4) Certification to the strength requirements of FMVSS Nos. 223 and 224 in 1998, although some earlier guards might have met those requirements; and (5) Certification to even greater strength requirements of CMVSS No. 223 in 2005; although not mandatory in the United States, current trailers are designed to the Canadian requirements to allow operation throughout North America.
Expected benefits: Passenger compartment intrusion increases fatality and injury risk in frontal impacts. Successful underride guards would reduce the likelihood of intrusion when cars or LTVs impact the rear of heavy trailers, without otherwise changing the distribution of delta v in those crashes. That should result in fewer deaths and serious injuries. The underride guards would have little or no effect in crashes where the car or LTV contacts the sides of the trailer or the truck that is pulling the trailer.
Fatality and serious-injury reduction: NHTSA’s evaluation, published in 2010, compares occupant fatalities in cars and LTVs when these vehicles impact the rear of heavy trailers to fatalities in a control group of crashes where the cars impact some other part of the trailer or impact the tractor.516 Two almost insuperable impediments to evaluation precluded statistically meaningful results: (1) FARS and most other databases available to NHTSA do not record the MY or VIN of trailers, leaving no clue as to the design of their underride guards; (2) The gradual evolution of standards for underride guards does not allow a simple before-after or all-versus-nothing comparison. As of 2010, Florida was the only State crash file available to NHTSA that recorded the trailers’ MY and VIN. The analysis is based on Florida data from CY 1989 to 2006; of course, the number of fatality cases in a single State is limited. The two categories of trailers considered are MY 1998 and later, which would include guards certified to FMVSS and/or CMVSS Nos. 223 and 224; and MY 1980 to 1993, before the TTMA voluntary standard, which would probably be mostly the narrow ICC/FMCSR guards. The technique is a multidimensional contingency-table analysis of car/LTV occupants’ odds of survival in rear impacts versus other impacts, in crashes with MY 1998+ versus MY 1980-to-1993 trailers – using a SAS procedure called CATMOD to estimate if the newer guards have reduced risk in rear impacts relative to the other crashes and also to control for the CY of the crash (because crash distributions in Florida have changed over time). The analysis estimates a 27-percent reduction in rear-impact fatalities with the newer trailers, but the estimate falls short of statistical significance, due to the limited data (chi-square = 0.88, where 3.84 is needed for significance at the two-sided .05 level). A corresponding analysis of the risk of fatalities and serious injuries (categories K and A in the Florida data) shows 6.5 percent lower risk with the newer guards, likewise not statistically significant.
Although the observed estimates are positive, the limited data and lack of statistical significance do not permit a conclusion that the newer guards have reduced fatalities or serious injuries. The model to compute lives saved in Part 2 of this report will not attribute any fatality reduction for car or LTV occupants to improved underride guards for heavy trailers. In a 2009 NHTSA analysis of 122 NASS-CDS fatality cases in frontal impacts, despite seat belt use and air bags, of cars and LTVs of MY 2000 or later, 12 of the 122 fatalities involve rear underride of a heavy trailer (although this data does not describe the type of underride guard on the trailer, which may have been built before FMVSS Nos. 223 and 224, or how the guard performed in the crash). 517
513 49 CFR, Parts 571.223 and 571.224; Federal Register 61 (January 24, 1996): 2004.
516 Allen, K. (2010, October). The effectiveness of underride guards for heavy trailers. (Report No. DOT HS 811 375, pp. 16-22). Washington, DC: National Highway Traffic Safety Administration. Available at wwwnrd.nhtsa.dot.gov/Pubs/811375.pdf.
517 Bean et al. (2009, September), pp. 33-39″
See numerous other posts and articles on the issue of underride guards: