Managing Speed Review of Current Practices for Setting and Enforcing Speed Limits -- Special Report 254 (1998) / Chapter Skim
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Chapter 4: Speed Enforcement and Adjudication
Chapter 4: Speed Enforcement and Adjudication
Pages 139-165
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From page 139... ...
In the preceding chapter, a range of methods for setting reasonable speed limits was discussed, reflecting trade-offs among safety, travel time, and enforceability on different types of roads and roadway environments. In this chapter, two additional requirements for driver compliance are considered: public support and consistent enforcement.
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From page 140... ...
The chapter begins with a discussion of the role of deterrence, surveillance, and sanctions in ensuring compliance with speed limits. Then, evidence of the effectiveness and the limitations of traditional enforcement methods on speed choice and safety outcomes is considered.
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From page 141... ...
. In the case of speeding, police officers must be able to reliably verify vehicle speeds and provide evidence that will hold up in court.
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From page 142... ...
If a court hearing is involved, judges have discretion to vary the penalties. Traditional police enforcement works in two ways: through detection and punishment of specific drivers who exceed the speed limit and through deterrence of speeding behavior in general.
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From page 143... ...
Just as drivers increase their compliance as the perceived likelihood of apprehension rises, police may reduce their level of enforcement activity when the unwanted behavior diminishes (Tsebelis 1993, 366367) .4 This close coupling of behavioral adaptation by the police and the driving public provides one explanation for the difficulty of sustaining the deterrence effects of traditional enforcement methods (Tsebelis 1993, 366; Bjørnskau and Elvik 1990, 139)
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From page 144... ...
APPLICATION OF DETERRENCE THEORY TO SPEED ENFORCEMENT Speed Enforcement Strategies Speed enforcement using mobile patrol vehicles measuring driving speeds with radar is the most popular means of conducting speed enforcement in the United States, according to a special survey conducted for this study (Figure 4-1) .5 State police use aircraft as well as laser and VASCAR for speed detection.6 The mobile patrol method involves a police vehicle circulating through traffic and citing speeding drivers.
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From page 145... ...
Resources for Speed Enforcement When the 55-mph (89-km/h) National Maximum Speed Limit (NMSL)
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From page 146... ...
Similar to earlier studies, the researchers found a marked reduction in average traffic speeds in the vicinity of the enforcement site to speeds close to posted speed limits (Hauer and Ahlin 1982, 277)
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Figure 4-2 Time expended on speed enforcement as a percentage of total enforcement efforts, based on replies to a survey of 50 state agencies responsible for traffic law enforcement conducted for this study. Responses were received from 34 of the 50 agencies.
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From page 148... ...
. There is some evidence that those who drive well in excess of the speed limit are the most impervious to the deterrence effects of traditional enforcement methods.
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From page 149... ...
Implications for Enforcement Strategies The foregoing evidence on the deterrence effect of traditional enforcement methods has several implications for both the uses and limitations of these methods. First, traditional enforcement "works" when the level of enforcement is sufficient to convince most drivers of the strong likelihood of detection and sanctions if they exceed the speed limit.
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From page 150... ...
ALTERNATIVE METHODS FOR INCREASING EFFECTIVENESS OF SPEED ENFORCEMENT Optimizing Traditional Enforcement Methods The deterrence effect of enforcement clearly depends on creating the impression that road users who violate the law have a high probability of being apprehended. One way to achieve a credible level of enforcement without overstraining enforcement resources is to enforce speed regulations where and when risk-taking behaviors are most evident and traffic volumes are sufficient to justify the effort (Zaal 1994, 1617)
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From page 151... ...
Laser speed measurement presents an attractive alternative to law enforcement agencies because it offers the ability to target individual vehicles more accurately on multilane roads and is more difficult to detect than conventional radar (Figure 4-3) .12 A recent study of the comparative effectiveness of radar and laser speed-measuring devices ( Jones and Lacey 1997)
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From page 152... ...
1 ft = 0.305 m. ter general deterrence effect and thus is superior for general-purpose enforcement.
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From page 153... ...
speed limit, approximating the design speed for this highway segment, along with photo radar resulted in the desired reduction in driving 14 Despite the greater precision of laser speed-measuring devices, the review of ASE technologies conducted for this study (Appendix D) did not find any examples of ASE systems that use laser technology.
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From page 154... ...
The program was launched with a massive publicity campaign in 1989, primarily on arterial roads with 37-mph (60-km/h) speed limits in metropolitan Melbourne and rural Victoria, where there had been serious injury collisions and validated complaints of excessive speeding (Coleman et al.
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From page 155... ...
Photo radar was deployed in staffed police vehicles on residential and arterial streets in both locations (Blackburn and Gilbert 1995, 34)
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From page 156... ...
Deployment of photo radar systems is simplest when the law holds vehicle owners responsible for speeding violations whether or not they were driving at the time of the infraction.19 This reduces the burden of providing a clear frontal photograph of the driver.20 Owner liability typically requires enabling legislation such as has been passed in Australia, the Netherlands, and some U.S. jurisdictions (Gilbert 1996, 7)
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From page 157... ...
First, it is important to deploy photo radar at sites where the safety record indicates and the public perceives there is a problem, perhaps including school and construction zones, locations with high crash rates, and sites where traditional police enforcement can be dangerous (e.g., urban Interstates) (Streff and Schultz 1992)
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From page 158... ...
Although these measures cannot guarantee success, they can ameliorate key obstacles to successful photo radar use. Publicity Whether new or conventional enforcement technologies are used, the effectiveness of speed enforcement can be enhanced by well-designed public information programs.
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From page 159... ...
The deterrence effect of sanctions for speeding violations is limited if lengthy court backlogs create a substantial lag between detection and punishment. New speed enforcement technologies, particularly photo radar, can simplify and streamline the adjudication process.
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Thus, efficiency may be gained at the price of effectiveness. Some successful photo radar programs use a combined approach.
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From page 161... ...
Because the police have other important enforcement priorities and limited resources, their preferred strategy is to create a widely perceived impression that those who exceed the speed limits beyond some small tolerance band will be detected and apprehended. This approach is successful only if motorists perceive that they have a nontrivial chance of being apprehended if they speed.
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From page 162... ...
If introduced selectively at first -- at especially hazardous roads and locations with high crash rates -- photo radar is likely to gain essential public support. Whether new or traditional enforcement technologies are used, a well-designed public information program can help boost the deterrence effect.
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From page 163... ...
1990. Public Opinion Regarding Photo Radar.
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From page 164... ...
1984. Increase in Traffic Safety by Surveillance of Speed Limits with Automatic Radar Devices on a Dangerous Section of a German Autobahn: A Long-Term Investigation.
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From page 165... ...
1994. Traffic Law Enforcement: A Review of the Literature.
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