Traffic Calming Devices Research Articles

Economic-environmental analysis of traffic-calming devices

A set of indicators are proposed to determine the effect of traffic-calming devices on the environment and economy. They are based on vehicular emissions and energy consumption and are used to evaluate the viability and positioning of traffic-calming devices. First, a time window is defined on which the influence of a traffic-calming device can be determined providing a convenient frame of reference. Second, a concept of local cruising conditions is defined in order to have a basis of comparison between cases “with” and “without” traffic calming devices. The emissions considered were: HC, NOx, CO, PM10, and CO2. From the latter fuel consumption was estimated. Valuation of speed bumps on a secondary road in Mexico City was obtained as an example application of the proposed methodology.

Techniques for on-board vibrational passenger comfort monitoring in public transport

Traffic calming devices on urban streets, such as elevated pedestrian crossings, speed bumps and roundabouts, are increasingly used, raising a real problem in relation to the on-board comfort that passengers perceive. To measure vibrational comfort related to traffic calming devices that passengers of the public transport perceive, an acquisition system called ASGCM (Autonomous System for Geo-referenced Comfort Measurements) has been developed, taking as a reference the European regulations on rail transports. ASGCM permits to link each measurement of vibration, ground velocity and acceleration with geographical information resulting from a GPS. In this way a map of a comfort index, statistical surveys and correlation between on-board comfort and traffic calming, can be directly obtained by any Geographic Information System (GIS), able to query a centralized remote database, which was developed ad- hoc. A large number of experimental tests has been performed to define a vibrational comfort index and to collect a large dataset that allows statistically significant comparisons between different infrastructures and their characterization. The proposed technique can also be useful for diagnostics purposes, such as vehicle comparison and road maintenance state monitoring.

Implications of upgrading a minor forest road on traffic and road-kill in southeast Queensland

The planned upgrade of a minor road in Brisbane connecting two suburbs through a forested area raised concerns about possible increases in road-kill in an area of high wildlife abundance and diversity. Extensive consultation with community representatives resulted in the incorporation of traffic calming devices in the design of the forested section of the road. To assess the effectiveness of these, road-kill surveys were carried out before and after the upgrade and vehicle numbers and speeds were obtained from traffic census data. Vehicle numbers almost doubled following the upgrade. The number of road-kills increased by a factor of three after the upgrade but there were marked differences for different sections of the road, with higher rates in suburban areas and lower rates in the forest section. The study supports previous work showing the importance of low speeds for reducing road-kill and showing that low speeds are best achieved by the inclusion of traffic calming devices in the road design.

Streetseen: Factors Influencing the Desirability of a Street for Bicycling

In what is one of the first visual preference surveys using Google Street View, adult students viewed a series of paired slides of image of city streets. Participants were asked to choose which image from the pair they preferred based on which street they would prefer to ride a bicycle. Subsequent analyses showed that differences in continent of the respondent impact preferences. This research demonstrates the extent to which certain segment-level factors such as presence of trees along the street, width of the street, presence of sidewalks, and other features are preferred using discrete choice models. The models reveal that increasing vehicle traffic, number of lanes, streetscapes with dense trees, and presence of parking lots decrease the probability of being chosen. Having sidewalks, presence of pedestrians, trees set back from the street, and traffic calming devices are positively associated with respondents’ preferences. The results related to trees may relate to perceptions of safety. For example, dense trees close to a street may limit visibility along a roadway. The models also reveal significant differences in preferences based on respondents’ locations. We conclude that this method is effective in capturing information about bicycling preferences. The survey methodology and analysis techniques introduced in this study can help city planners design streets that are preferred by bicyclists.

StreetSeen Visual Survey Tool for Determining Factors that Make a Street Attractive for Bicycling

In one of the first visual preference surveys to use Google Street View, adult students viewed a series of paired images of city streets and were asked to choose which image they preferred for riding a bicycle. Subsequent analyses showed differences by continent in respondents’ preferences. Discrete choice models were used to demonstrate the extent to which certain segment-level factors, such as presence of trees along the street, width of the street, presence of sidewalks, and other features, were preferred. The models revealed that increasing the vehicle traffic, number of lanes, tree density of the streetscape, or number of parking lots decreased the probability of image choice. The presence of sidewalks, pedestrians, trees set back from the street, and traffic-calming devices were positively associated with respondents’ preferences. The tree-related results may relate to perceived safety; for example, dense trees close to a street may limit visibility along a roadway. The models also revealed significant differences in preferences by respondent location. This method was effective in capturing information about bicycling preferences. The survey method and the analysis techniques introduced in this study can help city planners design streets that bicyclists prefer.

The Best Location for Speed Bump Installation Using Experimental Design Methodology

Speed bumps, as traffic calming devices, have been extensively used to reduce traffic speed on local streets. This study represents a unique application of experimental design methodology where the effects of some controllable factors in determining the best location for installing speed bumps before stop points (e.g. entry gates, road junctions) were investigated. Through Classical Design of Experiments (DOE), the optimum location of the speed bump was obtained based on the graphical plots of the significant effects. The speed at the stop point was treated as the response and minimum speed is desirable. Design-Expert® software was used to evaluate and analyze the results obtained. The suggested mathematical model effectively explains the performance indicators within the ranges of the factors. The car speed is the most significant factor that affects the distance-time in comparison with other factors, which provides secondary contributions.

Raised Crosswalks And Their Design Features InTraffic Calming

A road hump, or speed hump, is a traffic calming device used to reduce vehicle speed and volume on residential streets. Road humps are placed across the road to slow traffic and are often installed in a series of several humps in order to prevent cars from speeding before and after the hump. Speed humps are used in locations where very low speeds are desired and reasonable. Speed humps are typically placed on residential roads and are not used on major roads, bus routes, or primary emergency response routes. In Italy, the road humps are often built in the shape of raised crosswalks (RCWs) and they are generally placed both close and between intersections. This paper deals with the analysis of observed data on a sample of RCWs located in Tuscany, central Italy. Such data were referred both to geometry characteristics of the single raised crosswalk and recorded differences in vehicle speeds before and after it. Speed data were gathered using two automatic radarrecorders for each one of the sampled raised crosswalks. All the collected data were analysed firstly through statistical tests in order to assess their homogeneity or not between different locations and various types of roads; secondly, through modelling software to obtain a generally valid formulation to evaluate the functionality of the device. Finally, we were able to make some conclusions and highlight design aspects. On the one side, RCWs with similar geometries have similar effects on the lowering of vehicle speeds, regardless of local conditions (location, road geometry, driver behaviour, etc.). Moreover, recent developments of the research show that raised crosswalks installed in a series have an influence on the speed reduction in function of their number and their distance. On the opposite side, the effects of raised crosswalks with smaller heights (less than 6 cm) show clearly a very low influence on vehicle speed variations.

The Effectiveness of Temporary Traffic Calming Devices on Reducing Speeds of Traffic Flow in School Zones

The Effectiveness of Temporary Traffic Calming Devices on Reducing Speeds of Traffic Flow in School Zones

The Effectiveness of Temporary Traffic Calming Devices on Reducing Speeds of Traffic Flow in School Zones

Safety issue in school zones is one of the momentous problems in Thailand; in which mostly, the passing vehicles are often negligent to decelerate their speeds when entering to school areas. Chiefly, during the schools opening and closing times in a day, a number of students are usually staying in front of such schools. Henceforth, the effort of this study contributes to seek the efficient form of temporary traffic calming device to substantially decrease speeds of traffic flow. The study carried out the examination of three types of temporary traffic calming devices on assumption that they efficiently moderate speeds of traffic flow through the actual test at school zones in Rayong Province where a greater number of accident statistics were recorded. The findings evidently stated that two types of temporary traffic calming devices were suggested in effectively reducing speeds of traffic flow with statistical significance.

Use of speed profile as surrogate measure: Effect of traffic calming devices on crosstown road safety performance

Urban road safety management is usually characterized by the lack of sufficient, good quality crash data and low budgets to obtain it even though many traffic accidents occur there. For example, 54 percent of road crashes in Spain take place in urban areas, and 10 percent of urban fatal crashes occur on crosstown roads, which are rural roads that traverse small communities. Traffic calming measures (TCMs) are often implemented on these parts of rural roads that traverse small communities in order to reduce both the frequency and severity of crashes by lowering speeds, but evaluation of their effectiveness has been limited. The objective of this study was to develop a methodology using continuous speed profiles to evaluate the safety effectiveness of TCMs on crosstown roads as part of an integrated system in the absence of historical data. Given the strong relationship between speed and crash experience, safety performance can be related to speed. Consequently, speed can be used indirectly as a surrogate safety measure in the absence of crash and speed data.Two indexes were defined in this study as surrogate safety measures based on the continuous speed profile: Ra and Ea. Ra represents the absolute accumulated speed variations relative to the average speed and is inversely related to accumulated speed uniformity; and Ea represents the accumulated speed variations above the speed limit and is directly related to accumulated speeding. Naturalistic data were collected using GPS trackers for 12 scenarios with different TCM spacings. Then, the indexes were applied to individual observed speed profiles (individual analysis) as well as the operating speed profile (global analysis). The values obtained from individual and global analysis were statistically different. Spacing lower than 110m, which was found optimal from previous research, did not allow drivers to modify their speeds as the accumulated speed uniformity was quite similar regardless of the average operating speed; and, accumulated speeding was also minimized. Consequently, the scenarios where the TCMs were implemented according to the technical criteria presented a better design quality. On the other hand, age and gender differences did not seem to affect the average speeds or the accumulated speed uniformity and accumulated speeding.

SUITABILITY OF EXISTING TRAFFIC CALMING MEASURES FOR USE ON SOME HIGHWAYS IN EGYPT

ABSTRACTThe most common traffic calming measures on roadway network in Egypt are speed humps and cat-eye reflectors; the second one was investigated in previous study and found ineffective as traffic calming device on highways. This research examines the suitability of the existing speed humps on a major highway in Egypt for use, Cairo-Aswan agricultural highway was selected for this study, it is two-way two-lane highway, 140 km of it passing through Minia governorate and the posted speed limit is 90 km/h reduced to 60 km/h at dwelling zones. More than 150 speed humps exist on this highway in Minia region, located at intersections and entrance of towns and villages existing around that highway. Field measurements of speed, speed humps geometry, distance between humps, and in-depth interviews with different driver groups were used to assess the suitability of existing speed humps for use. The results show that most of speed humps are too high and some of them reach 25 cm height, low ground clearance vehicle' drivers complain that they cannot traverse without maneuvering speed humps, all drivers complain from rarity of signage, painting, and precautions which indicates the presence of speed humps, that led to traffic safety problems. Due to speed humps geometry, density of speed humps, and volume of traffic, much of delay and fuel consumption as well as damage of vehicles parts happen. The findings indicate that existing traffic calming measures are unsuitable for use in this class of highway.

Extent of Highway Capacity Loss Resulting from Road Humps

Road humps are traffic calming devices placed across road widths solely as speed reduction mechanism. They include, speed cushions, junction tables, road humps. Whilst it is clear that 75mm deflection like road humps would reduce speed to 20km/h on average, determining their impact on traffic flow rate has often been poorly reported. Based on the hypothesis that on any route with humps mean stream flow will lie within highway capacity loss envelope; moving car observer survey method was used to determine mean stream flows as well as a volumes and speeds of ‘with and without’ road humps sections. The studies were carried out under day light and dry weather conditions so as to eliminate their effects. An important part of the study is employment of dynamic passenger car equivalent values for the road sections. Results show significant highway capacity loss and the mean traffic flows lying within capacity loss envelope. The study concluded that although road humps are effective mechanism for vehicle speed reduction, their resultant highway capacity loss is significant.

An observational study of road safety around selected primary schools in Ibadan municipality, Oyo State, Southwestern Nigeria

Child pedestrians have been identified as vulnerable road users. Although walking as a means of transport has health and other benefits, it exposes children to the risk of road traffic injuries. This study was conducted to assess the availability of road safety features around government-owned primary schools in Ibadan municipality. A multistage sampling technique was used to select 46 of the 74 schools in the study area. Some (11) of the selected schools were sited within the same premises and shared a common entrance; thus a total of 35 school premises were eventually observed. Trained research assistants observed the school environment around the selected schools for road safety features such as location of schools, presence of "school", "child crossing" and "speed limit" road signs, and presence of traffic calming devices (road bumps or zebra crossing). Five (14%) of the schools were located on major roads and eight (23%) had road signs indicating that a school was nearby. Seven (20%) had road bumps close to the school, 15 (43%) had a warden who assisted children to cross, and none had a zebra crossing. Five (14%) schools had pedestrian sidewalks. The study revealed that the environment around a number of the observed schools in the municipality compromised the pupils' road safety. The local government, school authorities, parents, and road safety professionals need to institute definite measures to enhance the road safety environment around schools in the municipality.

Neighborhood Physical Features and Relationships With Neighbors

The objective was to investigate associations between features of the physical environment and neighborliness. Measures of the physical environment, including sidewalks, front porches, traffic-calming devices, bars on windows, and the presence of litter or graffiti, were collected using a systematic audit instrument in 10 neighborhoods in Portland, Oregon. Generalized linear regression models were created to model the odds of increasing neighborliness given access to the physical-environment factors of interest. The authors observed a greater probability of higher levels of neighborliness as the total number of positive physical-environment characteristics increased (cumulative odds ratio [95% confidence interval] = 1.69 [1.16, 2.45]) and the results were unchanged after controlling for race, self-reported health, perception of safety, years of neighborhood residence, age of house, market value of house, and proportion of homeowners in neighborhood. Modifiable features of the physical environment may be one mechanism through which people can enhance neighborliness.

Development and Validation of Speed Kidney, a New Traffic-Calming Device

Traffic calming has been widely applied to urban areas in recent decades to moderate speed and traffic volume. Because most measures used are physical, a vehicle must modify its path and speed. A benefit of traffic calming is improved safety from speed reduction and traffic volume reduction. However, traffic calming has disadvantages, such as emergency response delays, traffic diversion, noise, vibrations, damage to vehicles, and discomfort. Common traffic-calming devices do not consider discomfort for drivers who achieve an appropriate calmed and safe speed. Consequently, it was necessary to develop a new traffic-calming device to moderate speed and to minimize the disadvantages of the previous devices. The Highway Engineering Research Group of the Polytechnic University of Valencia, Spain, has invented, designed, and developed a new traffic-calming device, Speed Kidney. This paper provides the objectives of the Speed Kidney, a description of the new traffic-calming device, and its geometric design. The technological development of the device is described, as are the main results from preliminary tests, implementation on a campus street, and implementation on a controlled test track. Implementation criteria are also given. The Speed Kidney is a functional, feasible, sustainable, and safe solution for traffic calming.

Traffic Microsimulation Study to Evaluate the Effect of Type and Spacing of Traffic Calming Devices on Capacity

Traffic calming is widely implemented to improve road safety. However, the implementation of traffic calming devices implies less capacity of cross-town roads. The present research used traffic microsimulation to study the effect of traffic calming devices on the cross-town roads capacity based on different type and spacing of devices. Average delay was calculated. Then, capacity of the road was obtained for a fixed traffic calming device spacing as the flow rate from which delay presented exponential growth. Capacity of a cross-town road varied between 810 and 1300 vehicles per hour and lane with traffic calming devices spacing from 25 to 400 meters.

Speed Table Evaluation and Speed Modeling for Low-Volume Crosstown Roads

More than 50% of injury accidents in Spain take place on crosstown roads in urban areas. Traffic calming is an initiative to reduce the impact of traffic on local streets by lowering both the number and the severity of crashes. However, the implementation of traffic-calming devices in Spain was not standardized in the past, and no technical criteria were applied. The paper presents the methodology, results, and conclusions of an analysis specifically related to speed tables, which are flat-topped speed humps, as part of the research project MODETRA. For the research, five low-volume crosstown roads with 16 speed tables were selected to analyze drivers' behavior. Speed data were collected from a sample of more than 900 vehicles through the selected crosstown roads using Global Positioning System trackers. For each individual vehicle, a continuous speed profile along the path was obtained. The analysis showed that the minimum speed occurred when the vehicle left the traffic-calming device and the maximum deceleration occurred just before the device. Geometric characteristics of the speed tables were measured by using a digital profilometer. A wide dispersion in the geometry can be concluded. It was found that the speed reduction depended mainly on the separation between traffic-calming devices, whereas the speed over the speed tables depended crucially on the entrance-ramp slope, the speed table length, and the distance from the previous traffic control device. Also, no statistical correlations were found between speed table height and speed reduction or spot speed over the speed table.

Reducing Traffic Injuries Resulting from Excess Speed

This study investigates drivers' speed behavior on low-volume roads crossing small urban communities both without a gateway or traffic-calming device and with different forms of gateway and traffic calming along the urban environment. Speeds upon entering small urban areas in Italy were collected along several rural road sections. The site with the greater operating speeds was selected as the design site. Two gateways and integrated traffic-calming devices along the road were set up within the urban area. The gateways aimed to slow the vehicles entering the built-up area, and the traffic-calming devices aimed to complement the gateway effect. The proposed gateway design is a combination of low-cost and fast implementation measures. The traffic-calming treatments presented in the study could easily be implemented in other rural communities.

Investigation on North American Traffic Calming Decision Making Process

Traffic calming schemes are gradually becoming more widespread means of addressing concerns in residential streets. Although there has been a lot of recent research investigating the traffic calming programs, little research has been devoted to examining its decisionmaking process. Asian countries (e.g., Japan and Korea) have introduced several traffic calming devices but they have no distinct and methodical study procedure. The aim of this research is to illustrate a comprehensive review of North American traffic calming decisionmaking process practices. The scope of which is to serve as a basis for establishing the process guiding principle to introduce in Asian countries. This research reveals that most of the cities are having a warrant based system to check the suitability of traffic calming device. The result shows that the budget constraint is the most important reason to prioritize traffic calming projects while political intervention is the main drawback of the process.

Traffic calming along rural highways crossing small urban communities: Driving simulator experiment

The paper investigated drivers’ speed behaviour in a section of a rural highway crossing a small urban community in the existing scenario without any traffic calming device and in two different design scenarios with traffic calming in the urban community. Two gateways and four integrative traffic calming devices along the route within the urban area were tested. The gateways were aimed at slowing down the vehicles entering in the built-up area, while the traffic calming devices were aimed at complementing the gateway effect inside the built-up area. Two design options were tested: first option (alt1) is a combination of low cost measures, whereas the second option (alt2) is more expensive as includes a chicane and requires land acquisition. Drivers’ behaviour was investigated by means of a driving simulator experiment. The VERA dynamic-driving simulator operating at the TEST Road Safety Laboratory located in Naples (Italy) was used. Simulation results were validated by the comparison of speed behaviour in the real world and in the driving simulator, in the scenario without traffic calming. Analysis of the driving simulator experiment results was performed using two different approaches: (a) explorative description of data by cluster analysis; (b) inferential procedures about population using statistical tests. Cluster analysis was carried out in order to test if the drivers’ speed behaviour in the different design alternatives was substantially different. Statistical tests were performed in order to verify if speeds in specific sections were significantly different. Cluster analysis looked at speed profiles, whereas statistical tests looked at speed data in specific points. The obtained results showed a different behaviour of drivers approaching the urban community in the existing scenario and in the design scenarios. In the south direction, mean speed reduction ranging between 16 and 17 km/h, with 5% level of significance, was observed. In the north direction, mean speed reduction equal to 11 km/h, with 10% level of significance, was observed. Differences between the two design alternatives were not statistically significant. Along the urban community, a statistically significant mean speed reduction ranging between 9 and 15 km/h was observed in the south direction. In the north direction, speed reduction was not statistically significant. Overall, combined results of cluster analysis and statistical tests showed that the treatments were more effective in the direction with higher speeds in the base scenario.