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Interpretation ID: 77-2.33


DATE: 05/16/77


TO: Truck Body and Equipment Association Inc.


TEXT: This responds to the Truck Body and Equipment Association's February 8, 1977, petition for rulemaking to amend the definition of "unloaded vehicle weight" and to add a new definition to 49 CFR Part 571.3 for "special purpose vehicle." The National Highway Traffic Safety Administration (NHTSA) denies your requested rulemaking.

Your petition requests an amendment of the term "unloaded vehicle weight" similar to that proposed by Chrysler's December 20, 1976, petition. Both petitions recommend that, for purposes of barrier crash testing of certain vehicles, the unloaded vehicle weight be the lesser of the weight of a completed comparable model vehicle from which the particular vehicle is derived or 5,500 pounds. Further, you request an additional definition of "special purpose vehicle" that would distinguish vehicles designed for a specific work function from other vehicles produced from the same chassis. We have determined that the effect of creating such a vehicle category as special purpose vehicle in conjunction with the establishment of arbitrary weights for vehicles when undergoing compliance testing would, in some situations, undermine the effectiveness of the motor vehicle safety standards. Vehicles falling into the category could, according to your suggested scheme, be tested at a weight which differs from their actual weight as equipped.

In the case of Standard No. 301, Fuel System Integrity, such a result would possibly violate Congress order in the 1974 Amendments to the National Traffic and Motor Vehicle Safety Act (Pub. L. 93-492) that the NHTSA not diminish the level of safety established at that time in the standard.

To allow certain vehicles to be tested at a weight which differs from their actual weight, would permit the operation of vehicles which, as equipped, could fail the requirements of the standard.

You should note that the agency intends to proceed with the rulemaking to amend the definition of "unloaded vehicle weight" as recommended in a petition from Chrysler dated November 20, 1976. This amendment will incorporate changes in the definition previously made by the NHTSA through interpretation.



February 8, 1977

Petition to Define "Special Purpose Vehicle" and Amend the Definition of "Unloaded Vehicle Weight" Part 571 Motor Vehicle Safety Standards.

The Truck Body and Equipment Association (TBEA) on behalf of nearly one thousand final and intermediate manufacturers of trucks, truck bodies and allied truck equipment wishes to petition the NHTSA to add the definition of "Special Purpose Vehicles" and to amend the definition "Unloaded Vehicle Weight" to Part 571 -- Motor Vehicle Safety Standards.

The existing term "Unloaded Vehicle Weight" (U.V.W.) is used in several Federal Motor Vehicle Safety Standards to establish the weight (mass) of a vehicle to be barrier crash tested.

In the past, barrier crashes were only specified for passenger cars, but with the (Illegible Word) of FMVSS 301 Fuel System Integrity, barrier testing was extended to include trucks of up to 10,000 pounds GVWR.

The majority of the vehicles produced by our industry now are subject to the requirements of FMVSS 301 including the requirement to be able to survive a 30 mph head on barrier crash without spillage of a significant amount of fuel.

This crash test alone has necessitated the review and often total redesign of the specialized equipment produced by our industry, i.e. ambulances, dump trucks, farm trucks, utility trucks and tow trucks.

The Truck Body and Equipment Industry does not object to the intent of a fuel system performance standard but we do object to the manner in which any FMVSS requiring crash test is applied to the many final stage manufacturers of multistage manufactured vehicle.

It is apparent that the latest series of FMVSS will be much more complex than those initially issued. Even though truck production will be regulated by these standards it appears that the present definitions are directed to the passenger cars and pickup trucks but not to multistage manufactured vehicles. Our objection to the present test requirements is based on the fact that the NHTSA views both the manufacturer of an automobile and the manufacturer of a tow truck as final stage manufacturers.

By definition a "Final Stage Manufacturer" is "any person who performs such manufacturing on an incomplete vehicle that it becomes a completed vehicle".

In the truck manufacturing industry, this procedure is commonly referred to as taking a chassis (an incomplete vehicle) and making it "road ready". The process by which an incomplete vehicle is made "road ready" may vary from mounting a farm (Illegible Words) lights, to modifying a chassis cab into a complex piece of fire fighting equipments.

The network of truck manufacturers is immense, beginning with a handful of chassis manufacturers and extending outwards through thousands of final manufacturers. The most common type of final manufacturer is the truck body and equipment distributor. A distributor takes a chassis cab and installs a body or a piece of equipment on it and certifies that this completed vehicle complies with all existing federal motor vehicle safety standards at the time of manufacture. These small businesses (averaging less than 24 employees) are not in a position to do extensive engineering studies on each of their various types of vehicles. In order to comply with the numerous stands relating to their product, they rely heavily on support data from the chassis manufacturers. This component certification insures the distributor that when assembled the completed vehicle will comply with all applicable standards.

The back bone of the completed vehicle is the truck chassis. It is through this component, that the final manufacturer complies with many of the FMVSS. The chassis itself is extremely flexible allowing hundreds of body and equipment combinations to be installed on a single chassis type.

The light duty truck chassis, under 10,000 pounds GVWR, is an off shoot from the mass produced pick-up truck. Less than one in ten light trucks is scheduled for production as a truck chassis or incomplete vehicle. These low production numbers do not justify individual testing of each vocational type of truck produced, thus all available certification data is based on the pick-up truck. This is the point at which the (Illegible Word) "Unloaded Vehicle Weight" impedes our certification program.

The NHTSA defines "Unloaded Vehicle Weight" as:

The weight of a vehicle with maximum capacity of all fluids necessary for operation of the vehicle, but without cargo or occupants.

This term therefore results in low test weights based on the light pick-up body weight. As an example, a typical well equipped pick-up chassis with a 10,000 pound GVWR may weigh 4,400 pounds and its body may weigh 500 pounds for a total unloaded vehicle weight of 4,900 pounds. The truck chassis manufacturer would most likely test this vehicle at 5,000 pounds to insure S301 compliance.

Although the pick-up truck in this example is equipped with a vocational body designed to transport a cargo, many of the special purpose vehicles manufactured by our industry are designed to transport a piece of equipment such as an ambulance, a cherry picker, or a wrecker. These special purpose vehicles have a much higher unloaded vehicle weight. An example of one of our special purpose vehicles would be a utility vehicle equipped with a cherry picker or manlift. The same 10,000 pound GVWR chassis used for the pick-up at 4,000 pounds would be completed with an 1,900 pound utility body and a 2,500 pound aerial device for a total UVW of 8,800 pounds.

The higher UW causes a potential problem when considering any type of barrier (Illegible Word) test. When any vehicle is impacted into a stationary barrier, the vehicles entire energy or motion must be disipated through structural deformation, or crash.

The amount of crush realized during a barrier crash is proportional to the vehicles weight (mass) therefore two identical chassis with bodies of different weight, will receive different amounts of crush, the heavier the vehicle the more the crash. With the increase of crush, the chance of (Illegible Word) or separating some parts of the fuel system also increases. At some increases test weight, compliance with the barrier test requirements becomes questionable. This break point falls somewhere between 1.500 and 8.500 pounds for the present generation of pick-up chassis. In other words a chassis loaded to 7.000 pounds and crashed into a wall at 30 mph will most likely pass a 301 test where as a chassis loaded to 9.000 pounds won't.

Again, our objection to the barrier test is not with the intent, but with the procedure. In the real world condition, the pick-up truck loaded with a cargo of 3.900 pounds will react in the same manner as a utility vehicle when subjected to an actual accident.

Several years ago, the chassis manufacturers successfully demonstrated to NHTSA that carrier crashing of pick-up type vehicles at their GVWR's was questionable if not impossible. By the use of the present UVW definition, the NHTSA is requiring the many small final manufacturers within our industry, to assume the responsibility for certifying a completed vehicle to a performance level already questioned by the Agency and the chassis manufacturers.

At present, our only solution to the crash problem is to go to a larger chassis, above the 10.000 GVWR limit. This next step in chassis size may mean an increase of several thousand dollars per vehicle, not including the 10% Federal Excise Tax that then becomes effective.

We are concerned that in order to legally produce a vehicle with the same inherent safety qualities as a loaded pick-up, we are forced to purchase a larger chassis. pay 10% FET on the entire unit and still end up with a pre 301 vehicle. Why should a utility company be forced to purchase a $ 20,000 aerial device when the same piece of equipment could be produced for $ 15,000?

In an effort to alleviate this inequity place on our industry, we request that the Agency barrier test vehicles for standard compliance with weights more closely allied to the basic pick-up trucks.

This change could be accomplished by adopting a new definition for "Special Purpose Vehicles" and adopting Chryslers proposed definition for "Unloaded Vehicle Weight".

Special Purpose Vehicle -- means a motor vehicle of less than 10,000 pounds GVWR, designed to perform a specific work function, manufactured in two or more stages, and whose incomplete vehicle portion is derived from a truck or multipurpose passenger vehicle.

Unloaded Vehicle Weight -- means the weight of a vehicle with maximum capacity of all fluids necessary for operation of the vehicle, but without cargo, occupants, or accessories that are ordinarily removed from the vehicle when they are not in use. For purposes of barrier impact testing special purpose vehicles which are derived from multipurpose passenger vehicles, trucks or buses with a GVWR of 10,000 pounds or less, the unloaded vehicle weight shall be either that of the completed comparable model vehicle from which the special purpose vehicle is derived or 5,000 pounds, whichever is less.

The Truck Body and Equipment Industry has always demonstrated concern when considering the design and production of road safe vehicles.

The adoption of this amended definition would allow the many conscientious final manufacturers of trucks and related truck equipment to utilize test data already available through the chassis manufacturer.

It is also our contention that the adoption of this amended definition will pose no diminished level of motor vehicle safety.

Byron A. Crampton Manager of Engineering Services