Study for the Selection of Maximum Speed Limits. October 1970.

A Review of the Literature

"A Study for the Selection of Maximum Speed Limits." October 1970. Four (4) volumes, prepared for the National Highway Traffic Safety Administration (NHTSA), U.S. Dept. of Transportation, by the Indiana University's Institute for Research in Public Safety. IRPS report number FH-11-7275; Volume II is also federally numbered as PB 197 374, and DOD HS-800 379. I got my copy from the U.S. National Technical Information Service (NTIS). Volume II of the Final Report is about 140 pages long. Selected excerpts are:
From a historical perspective it can be seen that relatively few new ideas have been added in the area of speed limits since the early days of the automobile in America. Although this says much for the insight of the men who worked in this area in the early 1990s, it also illustrates the weak level of effort ascribed to speed control research since that time.

Little real progress has been made either in theory or in practice regarding modern speed regulation. Relatively few new concepts have been introduced, and most aspects of the speed problem remain highly unsettled.

The type of effect which speed limits have in questionable, and there is still no consensus as to whether they do or do not have an effect at all. It appears, however, that speed limits may have a favorable effect, or at least no unfavorable effects have been shown [p.109]

A study at the University of Illinois in 1947-1948 indicated the following [p.41]:

  1. Traffic ignores speed limits and runs at speeds which drivers consider safe for conditions;
  2. Speed vary little with traffic volumes up to the point where congestion begins;
  3. Most posted speed limits are ineffective because they are unreasonable; and,
  4. Sufficiently high, enforceable speed limits would expedite traffic and aid in enforcement.
A speed trap may be defined as a street or road which is wide enough, straight and smooth enough, and sufficiently free of obstructions limited visibility to permit driving at a certain speed but where the law nevertheless calls for a much lower speed. [p. 43, citing "Speed Traps and Safety" by Kay Lorentzen in Traffic Engineering, pp.167-168, January 1956]

Professor C. C. Wiley of the University of Illinois... concluded that traffic consistently ignored posted speed limits, and even the absence of posted speed limit signs, and ran at speed drivers considered reasonable, convenient and safe for existing conditions. Drivers operated by conditions rather than by their speedometers. And the general public paid little attention to what limits were posted. [p.46]

Gerald J. Driscoll, Chief of the Traffic Safety Service of the New Jersey division of Motor Vehicles, was quoted [in the Nov 1963 Traffic Digest and Review] as saying:

Ridiculously low speed limit signs only give a false sense of security, afford no protection, are a waste of money, and create a disrespect for all other control devices.
In 1965, J. Edward Johnston present a rather comprehensive summary of speed control information to the Institute of Traffic Engineers [p.101-102].
There is nothing wrong with many of our speed limits but there are not enough of that kind. The bad ones are unrealistic; they law violators out of normally law abiding citizens; they create a fearful driver; they subject drivers to unreasonable and punitive traffic laws; they are misleading and do not accomplish the safety that the public thinks they do; and they do not recognize the inherent desire of the public for mobility. The following premises... are offered as guide for your own conclusions in the matter of speed control and regulation:

The Book Back to the Ohio NMA rootpage.