deceleration forces) in otherwise similar crashes (e.g., barrier crashes at the same velocity). Designing
large, lightweight vehicles with soft structures that have acceptable ride and handling characteristics
(structural stiffness is desirable for obtaining good ride and handling characteristics) and are protective
against passenger compartment intrusion may be a challenge to vehicle designers. Additionally, the
differential needs for stiffness among lighter and heavier vehicles may cause compatibility problems in
multi-vehicle crashes.. In collisions with roadside obstacles, lighter vehicles have less chance than a heavier vehicle of
deforming the obstacle or evenrunning through it, both of which would decrease deceleration forces on
the occupants. Also, a substantial decrease in average vehicle weight might cause compatibility
problems with current designs of safety barriers and breakaway roadside devices (e.g., light poles),
which are designed for a heavier fleet.
. If weight reductions are achieved by shifting to new materials, vehicle designers may need considerable
time to regain the level of modeling expertise currently available in designing steel vehicles for maximum
safety.
There exist several safety design improvements that could mitigate any adverse effects caused
by large fleetwide weight reductions—though, of course, such measures could improve fleet
safety at any weight. Examples include external air bags deployed by radar sensing of impending
accidents; accident avoidance technology such as automatic braking; and improvements in vehicle
restraint systems (including faster acting sensors and “smart” airbags that can adjust to accident
conditions and occupant characteristics). The latter would greatly benefit from further
biomechanical research to improve our understanding of accident injury mechanisms.
Large fleet weight reductions also will intensify the need for the National Highway Traffic
Safety Administration to examine carefully its array of crash tests for vehicles, to ensure that these
tests provide incentives to maximize vehicle-to-vehicle compatibility in crashes.
A NOTE ABOUT COSTS AND PRICES
The price of advanced technologies is a controversial aspect of the continuing debate over the
merits of several government actions promoting such technologies. These actions range from the
alternative fuel vehicle requirements of the federal Energy Policy Act of 1992^69 to California’s
ZEV requirements to federal funding (in concert with industry) of PNGV. OTA’s estimates of
retail price differentials for advanced conventional vehicles are somewhat below industry
estimates, while estimates for hybrid, fuel cell, and electric vehicles seem to be above some others
prepared by advocacy groups. Part of the difference between OTA’s estimates and others
undoubtedly reflects the substantial uncertainty that underlies any efforts to predict future prices
of new technologies. Other differences arise from the following sources:
(^69) Public Law 486, Oct. 24, 1992.