The Traffic Accident Reconstruction Origin -ARnews-

Re: 5 mph bumpers?

Rusty Haight ([email protected])
Fri, 13 Dec 1996 10:41:39 -0500 (EST)

The term 5 mph bumper is terribly misleading. Prior to 1973, there was
effectively no bumper standard. In 1973, the feds put in place a standard
that protected cars in 5 mph front and 2.5 mph impacts to the rear. In
74-75, the standard was changed to protect cars front and rear to 5mph.
In 76-79 a 3mph corner standard was put in place. In 80-82 the same
standards were in place, but the definition of damage changed. In 83,
the standard was rolled back to 2.5 front and rear adn 1.5 on the corner.
(see FMVSS 215 or Title 49 C.F.R 571.215)

The question is: what is damage? For the most part, the standard
specifies a pendulum test where the pendulum has an impact face which
is to match up with the bumper on the tested vehicle. As a result of
this impact, at the specified speed, the car can sustain no damage to
the car's safety related components: headlights, doors, windshield, fuel
system and others listed in the standard.

Although we've rolled back the standard in this country, cars made by most
manufacturers for sale in Canada still have to mee their equivalent standard
which is still at 5mph or 8km/H.

The real question is: how do you use this information in the analysis of a
low speed collision? All too often, it's misused because people (a) don't
take restitution into account and (b) assume that the standard is for a delta-V
of 5mph (or 2.5mph...) when in fact that's not always the case.

Best of luck
Rusty Haight
[email protected]

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