Interpretation ID: 3317o

Mr. Clarence M. Ditlow III
Executive Director
Center for Auto Safety
2001 S Street, NW
Suite 410
Washington, DC 20009

Dear Mr. Ditlow:

This responds to your most recent letter to me concerning retrofitting of cars originally equipped with rear seat lap belts with rear seat lap/shoulder belts. In my November 1, 1988 letter to you, I explained that we have sought the voluntary cooperation of manufacturers to make retrofit kits available for those customers who desire them and that the vehicle manufacturers have responded positively to our efforts. I also explained that the fact that retofit kits are not available for all model lines produced by each manufacturer does not suggest some failure on the part of the vehicle manufacturers or of our policy to encourage the manufacturers to make such retrofit kits available.

In a November 7, 1988 letter, you asserted that my November 1 letter "reflects such callous disregard and ignorance of the facts as to defy belief that you are doing little more than covering up for a GM policy that will kill rear seat passengers." You stated that you would welcome a "substantive response" to this letter. I am happy to be able to give you such a response.

Let me begin by emphasizing that the lap belts in the rear seat of most vehicles on the road today are effective in reducing the risk of death and injury in a crash. Based on our analysis of a number of crash data files, we estimate that rear seat lap belts saved about 100 lives and prevented over 1500 serious injuries in 1987 alone. These figures would have been substantially higher if more rear seat occupants used their lap belts. In fact, if everyone had worn their rear seat lap belts each time they rode in a vehicle, those belts would have saved about 660 lives and prevented more than 10,000 serious injuries in 1987 alone.

These facts illustrate that the fastest and most effective way to save the greatest number of lives and prevent the greatest number of injuries is to convince the public to use the safety belts, including the rear seat lap belts, that are in their vehicles every time they ride in those vehicles. Because of these facts, I do not accept your assertion that GM's policy of not providing rear seat lap/shoulder belt retrofit kits for a few of their past models will "kill people." To the extent that reckless assertions like this tell the public that they should not wear their rear seat lap belts, it is unfortunate that you have chosen to divert attention away from the overriding issue of convincing the public to use their safety belts, and instead chosen to mislead the public about the quality of their safety belts.

Even though lap belts have been proven to be effective in reducing the risk of death and injury in a crash, we agree that properly designed lap and shoulder belts have the potential to offer even greater crash protection than lap belts alone. For this reason, we have proposed to require that all new passenger cars sold in the United States be equipped with rear seat lap and shoulder belts beginning in the 1990 model year. Additionally, we have actively sought the car manufacturers' cooperation in providing retrofit kits to interested consumers. As you may know, every domestic manufacturer and many foreign manufacturers now offer retrofit kits for many of their vehicle models.

You objected to General Motors' (GM) statement in its Information Bulletin that retrofit kits are not offered for its 1978-88 Oldsmobile Cutlass, Buick Regal, Chevrolet Monte Carlo, or Pontiac Grand Prix, "because GM safety engineers have concluded that in these cars, a rear seat lap/shoulder belt combination would not enhance the safety offered by the lap belt alone." You asserted that since Leonard Evans, a GM employee, has concluded that lap/shoulder belts are significantly more effective than lap belts and since the National Highway Traffic Safety Administration (NHTSA) is proposing to require rear seat lap/shoulder belts, there is no "possible scientific basis" for GM's conclusion.

NHTSA's proposal reflects our tentative conclusion that rear seat lap/shoulder belts that are designed and installed at the factory have the potential to offer even greater crash protection than lap belts alone for vehicles in general. However, any particular vehicle model's floor pan design, seat stiffness, and seat design (as it relates to occupant posture) can affect the possibility of an occupant submarining under a lap/shoulder belt system in a crash. During the design and production of the vehicle, the vehicle manufacturer can take these factors into account to minimize the likelihood of such submarining and its associated consequences.

However, this is emphatically not true for vehicles that were not originally engineered and designed to use rear seat lap/shoulder belts as original equipment. With respect to these vehicles, the effectiveness of a retrofitted rear seat lap and shoulder safety belt system may well depend on the belt system's compatability with the vehicle and the installation of the belt system. The suitability of a particular vehicle for retrofitting is therefore a complex question. It is our view that the judgment as to whether a retrofit lap/shoulder belt system should be installed in a particular vehicle is best made by a vehicle manufacturer, which is most familiar with the detailed seat and structural design and crash performance of the car.

I hope this information is helpful. Please let me know if you have any further questions or would like some additional information on this subject.

Sincerely,

Erika Z. Jones Chief Counsel

ref:208 d:12/22/88