OPTIMUM SPEED LIMIT. REVISED

In this paper, the authors describe an improved method of measuring the private and social benefits and costs associated with speed and give some simplified numerical examples. The examples illustrate that, without arbitrarily judging the value of human life, it is possible to: (1) estimate the optimum speed limit; (2) estimate the cost, per life saved, of a speed limit below the optimum, which can be compared with the cost of saving lives in other ways; and (3) specify the types of information needed to improve estimates of the optimum. The authors have considered only the simplest case, in which all drivers are rational and informed. Further, drivers have the same parameters and, hence, would choose to go the same speed if there were no speed limit. Thus, the authors are abstracting from any variation in speed and the externalities that fast and slow drivers impose on each other. The method involves using the speed individuals would go if unencumbered by a speed limit. For this, one needs to observe how fast drivers go in places where a limit is absent. The optimum speed limit is then obtained by adjusting this private speed so that the marginal benefits of extra speed equal the social marginal costs rather than the private. The authors conclude on the basis of their analysis that even if everyone would go the same speed without a speed limit, there are externalities present that justify a speed limit; and that the range of uncertainty about the optimal speed limit can be reduced drastically by paying close attention to driver behavior when there is no speed limit. (Author)

• Corporate Authors:

  Public Research Institute

  2000 North Beauregard Street
  Alexandria, VA  United States 
• Authors:
  • Jondrow, J
  • Bowes, M
  • Levy, R
• Publication Date: 1981-5

Media Info

• Pagination: 16 p.

Subject/Index Terms

• TRT Terms: Behavior; Benefit cost analysis; Costs; Drivers; Estimating; Optimization; Speed limits
• Subject Areas: Finance; Highways; Operations and Traffic Management; Safety and Human Factors; I73: Traffic Control;

Filing Info

• Accession Number: 00386722
• Record Type: Publication
• Report/Paper Numbers: PRI-PP-312-REV
• Files: TRIS
• Created Date: Jul 30 1984 12:00AM