Managing Speed Review of Current Practices for Setting and Enforcing Speed Limits -- Special Report 254 (1998) / Chapter Skim
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Appendix A: Trade-Off Decisions in Selecting Driving Speeds
Appendix A: Trade-Off Decisions in Selecting Driving Speeds
Pages 215-220
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From page 215... ...
Such a driver would probably also choose a vehicle designed to maximize speed and handling, perhaps at the expense of crashworthiness. At the other extreme, a driver unconcerned with minimizing travel time and concerned only with safety would probably drive much more slowly and would likely choose a vehicle designed primarily for crashworthiness.
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From page 216... ...
For drivers in many situations, the choice of driving speed is strongly influenced by speed limits and their enforcement, so the trade-off may be more one of travel time versus the likelihood and severity of penalties for exceeding the speed limit. But even in situations where there is little or no speed limit enforcement and many drivers exceed the posted speed limit, virtually no drivers are observed to drive as fast as their vehicles can go.
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From page 217... ...
The set of nondominated points is called the Pareto frontier.3 Notice that along the Pareto frontier, a driver must increase risk to reduce travel time and vice versa. 1 Risk is commonly defined as the product of probability and severity for a particular event.
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From page 218... ...
The driver's goal, then, is to select the point on the Pareto frontier that gives the highest utility, in this case Point E Drivers who place a very high value on their lives and are relatively indifferent to trip time will have relatively flat constant utility lines and will choose points with longer travel time and lower risk, like J or L
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From page 219... ...
Thus, the variance observed in highway speeds is, in part, a natural consequence of these different choices. The situation portrayed in Figure A-1 is further complicated because the Pareto frontier is subject to change, both by the individual and by public policy.
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From page 220... ...
Highways built to Interstate standards provide a driving environment with a lower risk for a given speed than do two-lane rural roads. Finally, through regulations such as speed limits combined with enforcement, public policy may prevent (or attempt to prevent)
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