NHTSA Report Number DOT HS 807 072 February 1987

An Evaluation of the Bumper Standard - As Modified in 1982

Warren G. La Heist and Frank G. Ephraim

Abstract

An evaluation of the Bumper Standard was conducted to determine actual benefits and costs and cost effectiveness of changes made (in 49 C.F.R. Part 581) in 1982. These changes, effective with the 1983 model year, reduced required damage resistance for passenger car bumpers from 5 mph longitudinal front and rear barrier and pendulum impacts and 3 mph corner pendulum impacts to 2.5 and 1.5 respectively. The requirement that there be no damage to the bumper itself beyond a 3/8 inch "dent" and 3/4 inch "set" (or displacement) from original position was changed to allow damage to the bumper itself while still requiring no damage to safety-related parts and exterior surfaces not involving the bumper. The evaluation was conducted under requirements of Executive Orders 12291 and 12498.

The evaluation compares collision damage experience and bumper system costs of 1983/84 models (post-standard modification) to a two year baseline of 1981/82 models (pre-modification). Manufacturers were selective in implementing the now minimum requirements, with only 35 percent of the cars sold in the U.S. in 1983 being equipped with bumpers that were changed in a way which reduced collision damage resistance when compared to the predecessor 1981/82 models. By the 1984 model year, slightly over 50 percent of models sold were equipped with bumpers changed in comparison to 1981/82 models.

The principal conclusions are:

(1) The costs to consumers have not changed as a result of the modification of the bumper standard from 5 to 2.5 mph.

(2) The net effect, over a car's 10 year life, is a small increase in repair cost, which is offset by a reduction in the cost of the bumpers.

(3) The change in the bumper standard has not affected the protection of safety-related parts.


Summary

On April 9, 1971, the National Highway Traffic Safety Administration (NHTSA) issued its first regulation on passenger car bumpers. Federal Motor Vehicle Safety Standard (FMVSS) 215, "Exterior Protection," was initially effective on September 1, 1972, and imposed requirements which prohibited damage to specified safety-related components such as headlamps and fuel systems in a series of perpendicular barrier impacts, at 5 mph for front and 2.5 mph for rear bumper systems.

Under subsequent legislation and regulations, performance requirements were changed several times. For the 1979 model year, the standard required that there be no damage to safety-related parts and exterior surfaces not involving the bumper system--a requirement known as Phase 1--at impact test speeds of 5 mph. The most stringent requirements were in effect for 1980 to 1982 models, and required 5 MPH longitudinal front and rear barrier and pendulum impacts, as well as no damage to the bumper itself beyond a 3/8 inch "dent" and 3/4 inch "set" or displacement from original position. These latter requirements which limited damage to the bumper are referred to as "Phase II." The last change in the bumper standard took place on May 14, 1982 when the requirements were modified, reducing the test impact speeds from 5 mph to 2.5 mph for longitudinal impacts and from 3 mph to 1.5 mph for corner pendulum impacts. The Phase II damage requirement was dropped and replaced with the previous Phase I requirement.

Drawing on the best available data and public comments, NHTSA completed a Final Regulatory Impact Analysis (FRIA) in support of the final rule amending the bumper standard to the 2.5 mph, Phase I requirement. The new requirement became effective on July 6, 1982, affecting 1983 and subsequent model year cars.

Executive Order 12291, dated February 17, 1981, requires Federal agencies to perform evaluations of their existing regulations, including those rules which result in an annual effect on the economy of $100 million or more. The objectives of an evaluation are to determine the actual benefits and costs of equipment, systems and devices installed in production vehicles in connection with a regulation -- and to assess cost effectiveness. Evaluation of standards is also consistent with, and part of, the Regulatory Program initiated under Executive Order 12498, dated January 4, 1985.

This evaluation compares the collision damage experience and bumper system costs of 1983 and 1984 models to a two year baseline consisting of 1981 and 1982 models which correspond to the period before the standard was modified. An important aspect of this comparison is the fact that manufacturers were selective in implementing the new minimum requirements of the regulation. In 1983, for example, only 35 percent of the cars sold in the United States were equipped with bumpers that, upon close scrutiny and analysis, were, changed in a way which reduced collision damage resistance -- in comparison to their 1981 and 1982 model predecessors.

In 1984, additional models were found to incorporate strength reducing changes, and other models, whose front bumpers had been reduced in 1983, now also were given reduced strength rear bumpers. By the 1984 model year slightly over 50 percent of the models sold were equipped with changed bumpers when compared to 1981 and 1982 models. Most of the changes were made to both the front and rear bumpers of a model.

It is important to define the term "changed," since the technique used for evaluating the effect of the bumper standard modification relies entirely on the difference between "changed" and "unchanged" bumper systems and comparing each of these populations to their 1981 and 1982 predecessors. Changed bumper designs are those make/model bumpers which in 1983 and/or 1984 were reduced in strength when compared to their 1981/1982 predecessors. Reduced strength was determined on the basis of a detailed examination of bumper designs and parts; it was not measured directly (i.e., by impact test). Unchanged bumper designs are the make/model bumpers which in 1983 and/or 1984 were essentially identical to their 1981/1982 predecessors. The cars with unchanged bumpers serve as the control group in the experimental design for the evaluation.

When referring to changes, alterations to general styling, aerodynamic flow shape and other "cosmetic" changes are excluded from the analyses and only the energy management components -- the major portion of a bumper system -- are considered. Consequently, the changes found in 1983 and 1984 bumpers were categorized into four mutually exclusive groups:

The fifth category is composed of those bumpers which were left unchanged from their 1981 and 1982 predecessors that had to meet the 5 mph, Phase II standard. Overall, the population of cars with changed bumpers averaged a curb weight of 2,690 lbs. in contrast to 2,920 lbs. for cars with unchanged bumpers. There appears to have been a tendency to change bumpers on the smaller models -- subcompacts and compacts -- more often than on intermediates and standard sized passenger cars.

As has been the practice for evaluations of regulations, the analyses of weight, cost and component identification were supported by "teardown" methodology, a complete disassembly and analysis performed under contract, on an average of 60 make/models for each of the four (1981 through 1984) model years in the study. Each year this number represented at least 85 percent of domestic production and 55 percent of import sales, or approximately 80 percent of the combined fleets. These data form the primary basis for the cost side in the benefit-cost analysis.

Estimation of benefits is based on differences in both damage frequency and repair cost between changed and unchanged systems, in 1983 and 1984, relative to their respective 1981 and 1982 predecessors, in low-speed collisions.

To focus on low-speed, bumper-related collisions two data sets are needed. One is obtained from a national survey of incidents not reported to insurance companies. The other is derived from a sample of insurance claim files screened to exclude incidents involving injuries and cases where the vehicle had to be towed from the scene. These sources and procedures are essentially the same as those used in the bumper evaluation published in April 1981.

The primary conclusion of the evaluation is that after two years in which certain design changes were made to a growing population of bumpers -- in response to a modified bumper regulation -- the road experience in terms of low-speed bumper-related collisions for the cars with changed bumpers has remained the same as the experience with cars equipped with bumpers manufactured to the previous 5 mph standard.

The principal findings and conclusions of the evaluation are the following:

Principal Findings

Bumper System Weights and Costs

Collision Damage Frequency

Damage Repair Cost

Damage to Safety Other Parts

Override and Underride

Benefits and Costs

Time and Inconvenience


Conclusions



Return to Regulatory Evaluation Page