Speed control with and without advanced warning sign on the field: An analysis of the effect on driving speed (original) (raw)
Related papers
Exceeding the Speed Limit: An Evaluation of the Effectiveness of a Police Intervention
Accident Analysis & Prevention, 1996
Driving too fast is probably one of the main contributors to the occurrence and severity of road accidents, and intention to speed is an important predictor of exceeding speed limits. This study examined the effect of a police intervention on exceeding the posted speed limit (speed of vehicles on the target road) and on intentions to speed (attitude questionnaire). The intervention consisted of a week in which 'police speed check area' warning signs were put up on the target 40 mph limit road, followed by a week of active police presence, followed by a further week in which the signs remained. The speed of vehicles was measured using police data collection equipment for a total of 7 weeks. The effect on the intentions of drivers using the road to exceed speed limits was assessed across age, sex and pre-intervention speeding behaviour using questionnaire measures. Fewer people broke the speed limit during the intervention than before, this effect lasting to a limited extent up to 9 weeks after police activity ceased and 8 weeks after signs were removed. The effect on drivers breaking the speed limit by large amounts was more transient. The intervention reduced intention to speed for subject groupings with high pre-intervention intention. Traffic flow contributed significantly to the variance in vehicle speed, but was not responsible for differences between the weeks, which may therefore be attributed to the intervention. Traffic flow also did not account for differences in speed between the two directions of traffic, which may therefore be attributed to the fact that the road areas preceding the target area in each direction differed in their speed limits (70 vs 30 mph). Intentions to speed, as well as speed adaptation difficulties are thought to contribute to these differences.
Safety, 2016
In this paper the results from a field experiment (conducted in 2012) are presented, in which 3 regional police units in the Flemish region of Belgium each tested a particular combination of a speed control (with mobile radar in an anonymous car) with communicative signage. The goal of this paper was to scientifically evaluate frequently used field setups. The following setups were tested in one week: (1) police unit 1: speed control with and without a static feedback sign placed after the control; (2) police unit 2: speed control with and without a digital feedback sign placed after the control; (3) police unit 3: speed display followed by a second speed display further along the road section. During certain time frames, speed control took place in between both signs. All tested field setups generated significant reductions in the speed level. Studying the effect of the different variations for each setup reveals that the effect of the speed control is generally larger in combination with the signage alongside the road. After the period during which the police activities took place, speed levels again reached their initial level. Based on the before-after analysis, only in police area 2 was a small 'time halo-effect' found. To generalize results from this pilot study, repetition of tested setups in the field is recommended as well as testing on a larger scale.
The effects of speed enforcement with mobile radar on speed and accidents
Accident Analysis & Prevention, 2005
In an evaluation study, the effects of targeted speed enforcement on speed and road accidents were assessed. Enforcement was predominantly carried out by means of mobile radar and focused on rural non-motorway roads. Information and publicity supported the enforcement activities. The evaluation covered a period of 5 years of enforcement. The speed data of these 5 years and the year preceding the enforcement project showed a significant decrease in mean speed and the percentage speed limit violators over time. The largest decrease was found in the first year of the enforcement project and in the fourth year of the project, when the enforcement effort was further intensified. There were similar decreases in speeding at both the enforced roads and at the nearby comparison roads that were not subjected to the targeted speed enforcement project, which may be explained by spillover effects. The best estimate for the safety effect of the enforcement project is a reduction of 21% in both the number of injury accidents and the number of serious casualties. This was based on comparison between the number of accidents/casualties during the enforcement project (5 years) and and the 8 preceding years on the enforced roads and at all other roads outside urban areas in the same region.
Accident Analysis & Prevention, 2005
In an evaluation study, the effects of targeted speed enforcement on speed and road accidents were assessed. Enforcementwas predominantly carried out by means of mobile radar and focused on rural non-motorway roads. Information and publicity supported the enforcement activities. The evaluation covered a period of 5 years of enforcement. The speed data of these 5 years and the year preceding the enforcement project showed a significant decrease in mean speed and the percentage speed limit violators over time. The largest decrease was found in the first year of the enforcement project and in the fourth year of the project, when the enforcement effort was further intensified. There were similar decreases in speeding at both the enforced roads and at the nearby comparison roads that were not subjected to the targeted speed enforcement project, which may be explained by spillover effects. The best estimate for the safety effect of the enforcement project is a reduction of 21% in both the number of injury accidents and the number of serious casualties. This was based on comparison between the number of accidents/casualties during the enforcement project (5 years) and and the 8 preceding years on the enforced roads and at all other roads outside urban areas in the same region.
Increased police enforcement: Effects on speed
Accident Analysis & Prevention, 1997
Results of a field experiment in which a 35-km long stretch of road was subjected to an increase in police enforcement-mostly as stationary speed controls-are presented. A group of police officers was invited to plan and perform the enforcement based on their own experience and ideas. The level of enforcement reached a daily average of nine hours throughout an enforcement period of six weeks. Speed measurements were done in 60 and 80 km/h speed-limit zones before, during and after enforcement withdrawal, and were compared to another stretch of road. Average speeds were reduced by 0.9-4.8 km/h in both speed-limit zones and for all times of day. For some time intervals, the average speed and the percentage of speeding drivers were reduced for several weeks of the after-period, demonstrating a time-halo effect of eight weeks at most. The percentage of speeding drivers was reduced in both speed-limit zones for all hours of the day except the morning rush hours 6.00-9.00 A.M. It is suggested that commuting drivers in the morning rush hours are most resistant to speed reduction. These results were statistically significant at ~=0.01. 0 1997 Elsevier Science Ltd
Study of the Impact of Police Enforcement on Motorists' Speeds
Transportation Research Record, 1999
One method to enforce speed limits on U.S. highways is through the use of police enforcement. One major problem with this approach is the high cost associated with the employment of police officers for patrolling purposes. Thus, the effectiveness of police presence in controlling highway speeds should be carefully assessed prior to making a decision on increasing police patrolling operations on the transportation network. A study was undertaken to evaluate the effects of police presence on the speed of vehicles in a recently increased speed-limit zone and to determine the "halo" effects of police presence (lasting effects when police are gone) on vehicular speeds. Data were collected on Interstate 96 in Ionia County, Michigan. Marked police cars circulated in both directions on the study segment, which was approximately 45 km (29 mi) long. Net speed reductions at a distance of 1.6, 3.2, and 4.8 km (1, 2, and 3 mi) upstream and downstream of each counter were used in the data analysis. Two methods were applied to study the effects of police presence. First, the average speed in the area without the police presence was compared to the average speed after the police presence. Second, the difference between the speed at the place where the police vehicle was positioned and the speed downstream was calculated. It was found that the average speed just upstream of the police car's location was reduced, but as soon as vehicles passed the patrol car, drivers accelerated to their normal speeds or more. Moreover, no "halo" effects on the vehicles at the increased speed zone under study were observed.
The effects of in-car speed limiters: field studies
2001
Field trials in three European countries, the Netherlands, Spain and Sweden were carried out in order to investigate the eects of an in-car speed limiter. The trials were carried out on urban and rural roads including motorways. A so-called unobtrusive instrumented car was used, where all the measuring equipment was hidden. All the speed limit categories in the respective countries, ranging from 30 to 120 km/h were included. The results showed that the eects of the limiter were greatest in free driving conditions outside platoons. However, the limiter also had eects in congested trac. Momentary high speeds were suppressed eectively, which resulted in less variation of speeds. Approach speeds at roundabouts, intersections and curves became smoother, car-following behaviour became safer in the speed range of 30±50 km/h. On the other hand, in the speed range of 70±90 km/h a slightly higher number of short time-gaps suggested less safe car-following behaviour. Other negative behavioural eects were slightly increased travel time and the increased frustration and stress for the drivers caused by the limiter. The majority of the subjects accepted the speed limiter as a driver-operated system. Half of the drivers would accept the limiter voluntarily in their cars. Ó 1th.se (A. Va Ârhelyi).
Driving speed on thoroughfares in minor towns in Denmark
2013
It is well documented that speeding increases the risk of injury accidents significantly. Earlier studies have found that there is significant speeding on thoroughfares (TF) where speed-calming measures such as speed bumps are not used. Speed-calming measures have local effect, but little is known about the effect of varying intervals between speed-calming measures on driving behaviour. In this study, Floating Car Data covering 579 trips on 14 TF are used to measure the effect of various speed-calming measures. The main results show that visual speed-calming measures (town entrances and speed limit signs) as well as physical measures (bumps, elevated areas, braking islands, and roundabouts) have an effect on speeding. The visual measures reduce speed somewhat although the mean speed continues to be well over the speed limit. On roads with 50km/h speed limit with physical speed-calming measures implemented at more than 225m intervals mean speeds up to 58km/h were recorded. With lower intervals (130-200m) speeding is limited. A model across all trips on the TF shows that more than 70% of the driving on TF is above the speed limit. The intervals between speed-calming measures affect the extent of speeding significantly. Also the proportion of densely built-up roadsides affects driving behaviour considerably, although this variable has limited effect on the highest speeds. For an appropriate speed to be kept on TF, physical speed-calming measures should be placed at intervals of about 150m. BACKGROUND Road safety is one of the most important issues regarding loss of years of life. In 2004, it was estimated that more than 1.27 million people globally died in road accidents (World Health Organization 2009). Despite significant improvements within the last five years in Denmark, the road safety statistics still show 167 fatalities and 3,600 injured in 2012 (Statistics Denmark 2013). Due to a significant number of dark figures the problem is much bigger than indicated in the official statistics. Only 14% of the injured were recorded herea share which is declining (Plovsing, Lange 2009). In addition, this problem is particularly challenging regarding vulnerable road users (Schepers et al. 2013), who are often the victims of traffic accidents in built-up areas. It is well documented that inappropriate speeds lead to a higher number of road fatalities, as represented by the Power Model developed by Nilsson (2004). Elvik too carried out a large-scale study. He generally agreed with the model and found that the most adequate value of power in relation to fatal accidents is 3.5 (Elvik 2009). That means that even minor speed violations affect the road safety significantly negatevely. E.g., if the mean speed increases from 50 to 55km/h, the number of fatal accidents increases by 40%. Also, it is found that increased mean speed on a road network increases the speed variation substantially, and that higher speed variation clearly affects road safety negatively (Finch et al. 1994, Salusjärvi 1981).
Comparison of Automated Speed Enforcement and Police Presence on Speeding in Work Zones
2008
This paper compares the effects of four speed management techniques on speed and speeding on interstate highway work zones. The techniques are speed feedback trailer, police car, the speed feedback trailer plus police car, and automated speed photo-radar enforcement (SPE). The effects on mean speed and degree of speeding were studied. The results showed that in both moderately and extensively speeding sites all law enforcement treatments (including variations of police presence and SPE) significantly reduced the mean speeds and degree of speeding. In the moderately speeding site, the Trailer+Police treatment reduced the mean speeds more than the other treatments. It reduced the mean speed of free flowing cars in the median lane by 8.4 down to 48.6 mph, while the other law enforcement treatments reduced it by 6.1 -6.4 mph. In the extensively speeding work zone, the Trailer+Police and the SPE treatments reduced the mean speeds similarly and more than the Police car alone. They reduced the mean speeds in the median lane by 7.8 mph down to 55.9 mph. In the moderately speeding site, Trailer + Police was more effective than the other treatments in reducing speeding. However, in the extensivelyspeeding site, all the law enforcement methods were similarly effective in reducing the speeding; yet 11% to 16% free flowing cars were speeding in median lane by more than 5 mph.