Ongoing Controversies

Although substantial areas of consensus have emerged in highway safety regulation, several controversies continue, primarily related to the proper balance between safety, mobility, and individual freedom.

Safety Versus Mobility

Motor vehicle injuries are part of the price paid for enhanced mobility. It might be possible to eliminate serious motor vehicle injuries almost completely by disallowing motor vehicles that can exceed 25 miles per hour (mph). In practice, there is a balance between mobility and safety, although where the balance is best struck can be quite controversial. The setting of speed limits has been an area of ongoing discussion and changing legislation. It has been estimated that raising the speed limit on rural interstate highways in the late 1980s resulted in about 400 additional deaths annually (Baum et al., 1991) and that in the 32 states that raised speed limits in 1996,1 about 350 more deaths occurred in the subsequent year than would have been expected based on historical trends (NHTSA, 1998).

Active Versus Passive Protection

Passive measures, including most vehicle modifications, are those that protect individuals automatically without cooperation or action on their part, for example, motorcycle headlights that are automatically turned on by the ignition key to increase daytime visibility of the motorcycle. In contrast, active measures require individual action by the person to be protected, for example, relying on motorcyclists to remember to turn on their headlights each time they ride during daylight hours. The advantage of passive measures is that, once in place, they protect virtually everyone. Active measures must be implemented by each person on each occasion to provide protection. The effect of requiring all vehicles to be equipped with so-called passive protections is to make the benefit-cost or mobility-safety trade-offs at the societal level rather than the individual level.

Clearly there are instances (as in the motorcycle headlight example above) in which passive measures are preferable, but in most cases such a clear-cut either/or situation does not exist. The overriding considerations in countermeasure choice are efficacy, effectiveness, acceptability, and cost. In reality, a combination of active and passive strategies is usually called for, and both have contributed to reductions in motor vehicle injuries.


The National Highway System Designation Act of 1995 (P.L. 104-59) eliminated the federally mandated national maximum speed limit of 55 mph.

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