Speed Limit Enforcement Research Articles

Road Traffic Injuries in Kenya: The Health Burden and Risk Factors in Two Districts

Background: Road traffic injuries (RTIs) contribute to a significant proportion of the burden of disease in Kenya. They also have a significant impact on the social and economic well-being of individuals, their families, and society. However, though estimates quantifying the burden of RTIs in Kenya do exist, most of these studies date back to the early 2000s—more than one decade ago. Objective: This article aims to present the current status of road safety in Kenya. Using data from the police and vital registration systems in Kenya, we present the current epidemiology of RTIs in the nation. We also sought to assess the status of 3 well-known risk factors for RTIs—speeding and the use of helmets and reflective clothing. Methods: Data for this study were collected in 2 steps. The first step involved the collection of secondary data from the Kenya traffic police as well as the National Vital Registration System to assess the current trends of RTIs in Kenya. Following this, observational studies were conducted in the Thika and Naivasha districts in Kenya to assess the current status of speeding among all vehicles and the use of helmets and reflective clothing among motorcyclists. Results: The overall RTI rate in Kenya was 59.96 per 100,000 population in 2009, with vehicle passengers being the most affected. Notably, injuries to motorcyclists increased at an annual rate of approximately 29 percent (95% confidence interval [CI]: 27–32; P < .001). The mean age of death due to road traffic crashes was 35 years. Fatalities due to RTIs increased at an annual rate of 7 percent (95% CI: 6–8; P < .001) for the period 2004 to 2009. Observational studies revealed that 69.45 percent of vehicles in Thika and 34.32 percent of vehicles in Naivasha were speeding. Helmets were used by less than one third of motorcycle drivers in both study districts, with prevalence rates ranging between 3 and 4 percent among passengers. Conclusions: This study highlights the significant burden of RTIs in Kenya. A renewed focus on addressing this burden is necessary. Focusing on increasing helmet and reflective clothing use and enforcement of speed limits has the potential to prevent a large number of road traffic crashes, injuries, and fatalities. However, it is difficult to demonstrate the magnitude of the injury problem to policymakers with minimal or inaccurate data, and this study illustrates the need for national continuous, systematic, and sustainable data collection efforts, echoing similar calls for action throughout the injury literature.

Speed Limits, Enforcement, and Health Consequences

This review summarizes current knowledge regarding the effects of speed limit enforcement on public health. Speed limits are commonly used around the world to regulate the maximum speed at which motor vehicles can be operated on public roads. Speed limits are statutory, and violations of them are normally sanctioned by means of fixed penalties (traffic tickets) or, in the event of serious violations, suspension of the driver's license and imposition of prison sentences. Speed limit violations are widespread in all countries for which statistics can be found. Speeding contributes more to the risk of traffic injury than do other risk factors for which estimates of population-attributable risk are available. Traffic speed strongly influences impact speed in crashes and therefore has major implications for public health.

Risk and expertise in the speed limit enforcement debate: Challenges, adaptations and responses

This article explores the changing role of expertise within a society increasingly subject to policies justified by a ‘risk’ narrative. It uses the ongoing debate around the use of speed cameras to enforce speed limits as a lens through which the twin challenges of the ‘demonopolization’ and ‘democratization’ of expertise can be understood. Drawing on empirical research conducted with those who view themselves as experts in relation to the issue of speeding it proposes, first, that traditionally conceived experts such as government officials, police officers and road safety practitioners have had to adapt to the reality of a ‘marketplace’ of expertise in which their own expert product must be marketed in order to compete with that of other self-proclaimed expert voices. Second, and drawing on research conducted with drivers themselves, this research proposes that these marketing strategies are being deployed for the benefit of a public which actually sees itself as emancipated from such external sources of expertise and able to claim expert status in its own right. The findings are of potential relevance to any policy maker, practitioner or pressure group seeking to use a risk narrative to legitimate or oppose a policy stance.

Impact of Driver Compliance on the Safety and Operational Impacts of Freeway Variable Speed Limit Systems

Variable speed limit (VSL) systems enable freeway system managers to change the posted speed limit on a section of roadway in response to varying conditions. VSL system goals may include homogenizing traffic flow, improving safety, and/or reducing driver stress. Although it is understood that the effectiveness of VSL systems is impacted by the level of driver compliance, which itself is influenced by the extent of speed limit enforcement, very little is known about the strength of these impacts. This paper uses a simulation model to evaluate the sensitivity of the safety and operational impacts of VSL to driver compliance. Several scenarios for driver compliance were modeled using the PARAMICS microscopic traffic simulator. Findings indicated that VSL impacts are very sensitive to the level of driver compliance. Safety was shown to be positively correlated with the level of compliance, and travel time was shown to be negatively correlated. However, it was also found that the magnitude of the impact is strongly influenced by the VSL control strategy (i.e., set of rules for incrementing and decrementing the speed limits) being used. Therefore, selection of the VSL control strategy cannot be done independently of the decision regarding speed limit enforcement.

Motorcycle Injury Severity in Barcelona: The Role of Vehicle Type and Congestion

Objectives: To determine factors affecting the severity of moped and motorcycle injuries in Barcelona—the city with the highest number of motorcycles per inhabitants in Europe—paying especial attention to differences across vehicle type and to the role of congestion in a city that has promoted powered two-wheelers (PTWs) to alleviate traffic density. Method: Drawing on Barcelona's local police census database on casualties (2002–2008), we use a parametric estimation based on an ordered multinomial logistic regression in order to identify factors affecting injury severity. We control for demographic characteristics, environment and traffic conditions, primary causes of accidents, and regulatory measures. Regressions distinguish PTW casualties from the rest of vehicles and present results for motorcycles and mopeds separately. Results: We confirm the higher vulnerability of PTW casualties—especially motorcycle casualties (OR 2.30)—and show that factors such as gender, excess speed, road width, and alcohol consumption do affect casualty severity. Regarding traffic conditions, we find that congestion diminishes the probability of suffering severe injuries, although its statistical significance only appears for motorcycle casualties (odds ratio [OR] 0.80), which are also more severe due to speed violations (OR 6.29). Conclusions: We confirm the negative relationship between traffic flow (congestion) and injury severity of PTWs casualties. This is clearly identified, at least for motorcycle casualties, although moped casualties present similar impacts as well. As a result, alleviating congestion through PTWs promotion turns out to be a trade-off between congestion and safety that public officers must consider. The article also highlights the need of awareness campaigns and safety policies focused on specific groups of drivers. Attention should also be given to the enforcement of speed limits and alcohol restrictions in Barcelona.

Traffic noise affects forest bird species in a protected tropical forest

The construction of roads near protected forest areas alters ecosystem function by creating habitat fragmentation and through several direct and indirect negative effects such as increased pollution, animal mortality through collisions, disturbance caused by excessive noise and wind turbulence. Noise in particular may have strong negative effects on animal groups such as frogs and birds, that rely on sound for communication as it can negatively interfere with vocalizations used for territorial defense or courtship. Thus, birds are expected to be less abundant close to the road where noise levels are high. In this study, we examined the effects of road traffic noise levels on forest bird species in a protected tropical forest in Costa Rica. Data collection was conducted in a forest segment of the Carara National Park adjacent to the Coastal Highway. We carried out 120 ten minute bird surveys and measured road noise levels 192 times from the 19th to the 23rd of April and from the 21st to the 28th of November, 2008. To maximize bird detection for the species richness estimates we operated six 12 m standard mist nets simultaneously with the surveys. The overall mist-netting effort was 240 net/h. In addition, we estimated traffic volumes by tallying the number of vehicles passing by the edge of the park using 24 one hour counts throughout the study. We found that the relative abundance of birds and bird species richness decreased significantly with the increasing traffic noise in the dry and wet season. Noise decreased significantly and in a logarithmic way with distance from the road in both seasons. However, noise levels at any given distance were significantly higher in the dry compared to the wet season. Our results suggest that noise might be an important factor influencing road bird avoidance as measured by species richness and relative abundance. Since the protected forest in question is located in a national park subjected to tourist visitation, these results have conservation as well as management implications. A decrease in bird species richness and bird abundance due to intrusive road noise could negatively affect the use of trails by visitors. Alternatives for noise attenuation in the affected forest area include the enforcement of speed limits and the planting of live barriers.

Speed Limit Enforcement as Perceived by Offenders: Implications for Roads Policing

Copyright@ 2010 The Authors. This is the post-print version of the article. The final published version may be accessed at the link below.

The United States of America and the Islamic Republic of Iran: the path to preventing traffic injuries?

The United States of America and the Islamic Republic of Iran: the path to preventing traffic injuries?

Biomarkers in the Clinical Diagnosis and Management of Traumatic Brain Injury

Traumatic brain injury (TBI) is the leading cause of death and disability among young adults. Numerous safety improvements in the workplace, the addition of airbags to vehicles, and the enforcement of speed limits have all helped to reduce the incidence and severity of head trauma. While improvements in emergency response times and acute care have increased TBI survivability, this has heightened the necessity for developing reliable methods to identify patients at risk of developing secondary pathologies. At present, the primary clinical indicators for the presence of brain injury are the Glasgow Coma Scale (GCS), pupil reactivity, and head computed tomography (CT). While these indices have proven useful for stratifying the magnitude and extent of brain damage, they have limited utility for predicting adverse secondary events or detecting subtle damage. Biomarkers, reflecting a biological response to injury or disease, have proven useful for the diagnosis of many pathological conditions including cancer, heart failure, infection, and genetic disorders. For TBI, several proteins synthesized in astroglial cells or neurons have been proposed as potential biomarkers. These proteins include the BB isozyme of creatine kinase (CK-BB, predominant in brain), glial fibrilary acidic protein (GFAP), myelin basic protein (MBP), neuron-specific enolase (NSE), and S100B.The presence of these biomarkers in the cerebrospinal fluid and serum of patients with moderate-to-severe TBI, and their correlation with outcome, suggest that they may have utility as surrogate markers in clinical trials. In addition, many of these markers have been found to be sensitive indicators of injury, and therefore may have the potential to diagnose persons with mild TBI. In addition to biomarkers that correlate with long-term outcome, a few studies have identified prognostic biomarkers for secondary injury that may be useful in individualizing patient management.

The Techno-Fix Versus The Fair Cop: Procedural (In)Justice and Automated Speed Limit Enforcement

While the use of technology to monitor and punish suspected ‘risky’ populations is likely to increase, the experience of being on the receiving end of such enforcement has received relatively little attention. This paper presents research that considered one particular criminal justice ‘techno-fix’—the speed camera—from the perspective of those who encounter the technology as offenders. Such enforcement is commonly described by drivers as being ‘unfair’ and ‘unjust’. Speeding drivers’ experiences of being ‘techno-fixed’ are considered with reference to the antecedent elements of a procedurally just experience proposed by Tyler amongst others. Drivers’ preferences for fairer methods of speed limit enforcement are then analysed, before the potential for reconciling the ‘techno-fix’ with procedurally just enforcement is considered.

Road safety: A call for action.

Road safety: A call for action.

The Impact of Speed Limits on Recreational Boating in the Lagoon of Venice

Speed limits were introduced in the Lagoon of Venice in 2002 to reduce wave motion, which damages environmentally sensitive areas in the broader Lagoon as well as buildings in the city of Venice. In this paper, we estimate the welfare losses experienced by recreational boaters as a result of the speed limits. We fit a single-site travel cost model to a sample of boaters intercepted as they depart from or arrive to marinas and launching ramps on the Lagoon. Our Poisson model is corrected for truncation and endogenous stratification. We construct three measures of the price per trip, which allow us to check the sensitivity of models and welfare estimates to possible measurement errors in the opportunity cost of time. Our results are robust to the measure of price used and conservatively peg the welfare losses of boaters to €5.2-6.7 million per year. Even under conservative assumptions, the welfare losses of boaters are sufficiently large that, given current monitoring and enforcement of the speed limits, we believe there is a strong incentive for boaters to disregard the limits. Paolo Rosato Anna Alberini Dimitrios Reppas Valentina zanatta1

Evaluating Factors Affecting Safety at Highway–Railway Grade Crossings

Various countermeasures can be introduced to reduce collisions at highway–railway grade crossings. Existing improvements to crossings include the installation of flashing lights or gates, the addition of extra warning devices such as four-quadrant barriers or wayside horns, and the enforcement of speed limits on the approaching highway. Statistical models are needed to ensure that countermeasures introduced at a given crossing are both cost-effective and practicable. However, in large part because of issues of colinearity, poor statistical significance, and parametric bias, many existing statistical models are simple in structure and feature few statistically significant explanatory variables. Accordingly, they fail to reflect the full gamut of factor inputs that explain variation in collision frequency at individual crossings over a given period of time. Before statistical models can be used to investigate the cost-effectiveness of specific countermeasures, models must be developed that more fully reflect the complex relationships that link a specific countermeasure to collision occurrence. This study presents a sequential modeling approach based on data mining and statistical methods to estimate the main and interactive effects of introducing countermeasures at individual grade crossings. This paper makes use of Canadian inventory and collision data to illustrate the potential merits of the model in decision support.

Evaluating Factors Affecting Safety at Highway-Railway Grade Crossings

Various countermeasures can be introduced to reduce collisions at highway-railway grade crossings. Existing improvements to crossings include the installation of flashing lights or gates, the addition of extra warning devices such as four-quadrant barriers or wayside horns, and the enforcement of speed limits on the approaching highway. Statistical models are needed to ensure that countermeasures introduced at a given crossing are both cost-effective and practicable. However, in large part because of issues of colinearity, poor statistical significance, and parametric bias, many existing statistical models are simple in structure and feature few statistically significant explanatory variables. Accordingly, they fail to reflect the full gamut of factor inputs that explain variation in collision frequency at individual crossings over a given period of time. Before statistical models can be used to investigate the cost-effectiveness of specific countermeasures, models must be developed that more fully reflect the complex relationships that link a specific countermeasure to collision occurrence. This study presents a sequential modeling approach based on data mining and statistical methods to estimate the main and interactive effects of introducing countermeasures at individual grade crossings. This paper makes use of Canadian inventory and collision data to illustrate the potential merits of the model in decision support.

Enforcement of speed limits—actual policy and drivers’ knowledge

This paper reviews the penalty rules and examines drivers’ perceptions of enforcement of speed limits. The survey was carried out using a sample of 204 Norwegian drivers, answering questions in a setting closely associated with their driving situation. For minor speeding offences drivers overestimated on average their fines. For serious speeding offences drivers significantly underestimated how many kilometers per hour they could exceed the speed limits before losing their driving license. They also overestimated the probability of being caught speeding. This resulted in a perceived expected penalty twice the real one. The paper also examines the relationship between different driver characteristics and their knowledge of the enforcement policy for speeding. Older drivers had less knowledge about the threshold level for serious speeding but more knowledge about the detection rate than younger drivers do. Experienced drivers had more knowledge about the threshold level for serious speeding than inexperienced drivers. The number of times drivers were stopped due to speeding offences increased their knowledge of fines for minor speeding.

VEHICLE SPEED CONTROL USING ROAD BUMPS

Road bumps play a crucial role in enforcing speed limits, thereby preventing overspeeding of vehicles. It significantly contributes to the overall road safety objective through the prevention of accidents that lead to deaths of pedestrians and damage of vehicles. Despite the importance of road bumps, very little research has been done to investigate into their design. While documentation exists on quantitative descriptions of road bumps, they offer little guidance to decision making. This work presents a unique approach to solving road bumps design problems. The results of our study reveal three important road bumps variables that influence the control of vehicle speeds. The key variables are bump height, bump width, and effective distance between two consecutive road bumps. Since vehicle speed control is the ultimate aim of this study the relationship between vehicle speed and other variables earlier mentioned is established. Vehicle speed is defined as the product of frequency at which a vehicle is moving over road bumps and the sum of effective distance between two consecutive road bumps. In the determination of bump height we assume a conical shaped curve for analysis as a matter of research strategy. Based on this, two stages of motion were analysed. The first concerns the motion over the bump itself while the second relates to the motion between two consecutive road bumps. Fourier series was then used to formulate a holistic equation that combines these two stages. We used trigonometric functions to model the behaviour of the first stage while with the second stage giving a functional value of zero since no changes in height are observed. We carried out vibration analysis to determine the effect of road bumps on a vehicular system. Arising from this a model component is referred to as an isolation factor. This offers guidance to the safe frequency at which vehicles could travel over road bumps. The work appears to contribute to knowledge in road bump research through the development of a novel approach to the control of vehicle speeds. Significant research progress could be made if engineering and academic communities at large appreciate our viewpoints. With this work it is apparent that varying of the assumptions made in terms of bump shape may produce high proliferation of beneficial research studies. Although this work may reveal a new way of investigation into road bump research, no claim is made for the work comprehensiveness. We expect experts to challenge some of our thoughts and ideas presented in this work.

Analysis of the Effects of Speed Limit Enforcement Cameras: Differentiation by Road Type and Catchment Area

A detailed statistical analysis is presented of the effects of speed limit enforcement cameras on injury accident numbers. The approach used is constructed in such a way that it is possible to differentiate not only between the effects of the cameras and the effects of trend and seasonality but actually to produce estimates that are independent of any other overall time-dependent effects. Crucially, the estimates produced are also net of the effects of regression to the mean. To allow for the simultaneous treatment of the different levels of severity, weights are used that reflect the frequency of the different types of accidents. This approach is then used on a data set for all injury accidents in Cambridgeshire between 1990 and 2002, which also contains data from 49 camera sites. To quantify the range of effectiveness of the cameras, estimates of the changes in accident numbers are produced for different distances from the camera site. The analysis shows that, overall, in the immediate vicinity of the camera sites, the installation of a camera can be expected to lead to decreases in weighted injury accident numbers by an astounding 45.74%. Lower, but still significant, decreases are observed in the wider surrounding area. Finally, to provide further insight into the differences in performance on different road types, the sites are grouped together according to road category. This analysis shows that the biggest reduction in accident numbers can be obtained on roads with a higher incidence of speeding offenses.

Speed control in developing countries: issues, challenges and opportunities in reducing road traffic injuries

Speed has been determined to be one of the most common contributing factors in vehicle crashes. This study explores vehicle speed as a factor in the causation of road traffic crashes, using the example of Ghana. It examines the effectiveness of various speed control measures, based on policereported traffic crashes in Ghana and published works on speed control measures in both industrialized and developing countries. In Ghana, pedestrians were the main victims of road traffic injuries. The dominant driver error assigned by traffic police was loss of control, with the underlying factor being excessive vehicle speeds. The ‘speed factor’ alone accounted for more than 50% of all Ghanaian road traffic crashes between 1998 and 2000. While the enforcement of speed limits by traffic police may not be affordable for most developing countries, rumble strips and speed humps were found to be effective on Ghanaian roads. Rumble strips installed on the main Accra-Kumasi highway reduced crashes by about 35% and fatalities by about 55%. Reducing vehicle speeds may be one of the most effective interventions to stem traffic crashes in low-income countries. However, setting lower speed limits is not an effective intervention without the traffic law enforcement resources to ensure that limits are followed. Developing countries must also look to other speed reduction measures such as speed bumps and rumble strips, roads that segregate high- and low-speed users, and technological solutions such as speed governors, as well as greater public awareness of the problem.

Effects of Speed Limit Enforcement Cameras on Accident Rates

Speed limit enforcement cameras (SLECs) have been in operation in Great Britain since 1991. However, there is still considerable dispute regarding their effectiveness in reducing accident rates. The aim of this research was to analyze the effects of SLECs on accident rates in Cambridgeshire, United Kingdom, using time series data collected over an 11-year period. A time series analysis of the accident data revealed the presence of both trend and seasonality components. A method was developed to remove the influence of these two components from the data and compare mean accident levels before and after installation of the camera. The method was also constructed in such a way that it would be able to distinguish between the actual effects of the camera installation and the effects of regression to the mean. The initial investigation into the effects of SLECs showed an average decrease over sites in the monthly accident frequency by around 18%; a more detailed analysis suggested that the best approximation of the effect of the introduction of a SLEC is a decrease in injury accidents by 31.26%, thus giving clear evidence that SLECs do indeed contribute to a significant decrease in accident numbers.

Road traffic accident mortality in Singapore

The aim of this study was to identify factors that contribute to road traffic accident mortality and the patterns of injuries sustained by these victims, with a view to identifying areas for future intervention. All road traffic accident deaths that occurred in Singapore over a period of 1 year were reviewed. A total of 226 deaths occurred: 82.3% of the victims were male. The median age was 31 years. Blood alcohol was detected in 42 (18.7%) victims. In general, head (86.7%), followed by thoracic (67.7%) and abdominal (31.4%) injuries, were the most common injuries. Severe lower extremity trauma was most common among pedestrians and pedal cyclists (20.6% and 11.0%, respectively). The mean Injury Severity Score was 38.7. The relative risk of mortality between motorcyclists and motorcar drivers was 18.8:1. Suggestions for future prevention and intervention include stricter enforcement of speed limits, more severe penalties for drunk driving, helmet use among pedal cyclists, and the introduction of pre-hospital advanced airway management.