This study investigated, by means of a dynamic driving simulator experiment, road users’ behavior inside the curves of rural two-lane highways related to different advance warning signs, perceptual ...measures, and delineation treatments. These treatments were intended to warn drivers of the presence of low radius curves and to affect their behavior, improving vehicle control and lane-keeping. Five surrogate measures of safety were used in the evaluation of the design alternatives in relation to lateral position performance: standard deviation of lateral position, maximum encroachment in the shoulder, maximum encroachment in the opposite lane, relative length of shoulder encroachment, and relative length of opposite lane encroachment. Statistical tests were performed to verify whether the surrogate measures of safety were significantly different between alternatives. The analysis was divided into three phases. In the first phase, all the measures were preprocessed, testing normality and homoscedasticity assumptions. In the second phase, the presence of an overall effect considering all the alternatives was evaluated using analysis of variance and the Kruskal–Wallis test. In the third phase, Student’s t- and Mann–Whitney tests were used to assess which alternatives showed statistically significant effects. The results demonstrated that the perceptual measures, namely colored transverse strips, dragon teeth markings, and colored median island, were the most effective treatments. Field tests to establish the perceptual measures’ effectiveness on real roads are strongly advised. Implementation of the measures tested in the driving simulator should be carried out on similar rural highways to validate the results.
A computational system consisting of an urban mobility simulator, validated fluid dynamics and an integral exposure model, is proposed to obtain cyclist and pedestrian exposure to PMx and NOx. ...Pedestrian activities in the urban anthroposphere include walking and running. The computational experiments take place in a computer-generated urban canyon, subject to emissions from diesel and gasoline Euro 5 and Euro 6 vehicular technologies, in continuous and stop-and-go traffic scenarios, and three wind directions at two speeds. The exposure time in the computational domain of slow and fast pedestrians were obtained. Slow pedestrians had exposure times around 17% more than fast pedestrians due to their higher sidewalk residence time. Runners and cyclists decreased their exposures by 57% and 73% respectively compared with walkers. Two traffic scenarios are implemented: one due the presence of a hump and another without a hump. The presence of the hump, increased exposure and fuel consumption by 60% per heavy duty vehicle, about 44–48% per light duty vehicle and about 54–71% per passenger car. Vehicular technology had a large influence on exposure: Heavy duty-Euro 6 vehicle decreased 86% the exposure to PM2.5 and 66% to NOX with respect to Euro 5.
The proposed computational system provides information on how wind velocity influenced the inhomogeneous pollutant distribution in the street-canyon, causing exposure to be dependent on pedestrian route location. Microscale sidewalk areas in the order of meters containing higher concentrations were thus located. The cleanest routes in the urban canyon were identified. When the wind intensity doubled from 2 to 4 m s−1, exposure concentration decreased around 45%. The proposed system provides a computational platform to study urban atmospheric fluids, scenarios such as pedestrian routes, vehicular technologies, traffic velocities, meteorological conditions and urban morphology affecting pollution exposure.
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•Sidewalk human exposure scenarios in an urban canyon.•A system of interconnected urban mobility, computational fluid dynamics and exposure models.•Concentration field in the urban atmosphere provided by a validated computational fluid dynamics model.•Sidewalk exposure depends on time of residence, pedestrian and cyclist's route, traffic flow, vehicular technology, local meteorology and urban morphology.
The present study investigates the speed behaviors of drivers encountering speed humps on urban and suburban roads. The purpose is to optimize the geometric dimensions of different types of speed ...hump by considering ride comfort and driving safety criteria. Field observations of drivers’ behavior were conducted near 90 speed humps in eight cities in Mazandaran Province, Iran. Vehicles speed modeling was carried out using multi-layer perception and normalized radial basis functions artificial networks. The sensitivity analysis results of artificial neural network (ANN) models showed different factors associated with speed humps’ performance. While the length of entrance and exit ramps and passage width were the most influential factors in urban roads, speed before the humps’ position plays a crucial factor in suburban roads. Finally, the optimum geometry of speed humps was presented by ANN models for different types of roads.
This paper examines the effectiveness of multiple traffic calming measures on an urban residential road network in Asaka City, Japan. The study combines analysis of driving speed data with resident ...survey data. The public acceptance of infrastructure projects is essential for achieving goals sustainably. More than 50% of residents surveyed believed the neighborhood became more livable with more peace of mind after the installation of speed humps. Speed surveys were conducted both before and after the construction of 7 speed humps which included smooth pedestrian crossing humps and intersection humps. Drivers became more cautious at all locations with the presence of humps. Results of the residents’ opinion survey were validated with the speed survey data of the 85th percentile speed and speed profiles. The findings suggest that area-wide traffic calming measures can be effective in reducing driving speed and improving the perception of safety and quality of life for residents in urban residential areas.
This paper attempts to measure the vehicle speed characteristics at few predetermined points along four residential roads. The selection of points to measure vehicle speed is to understand the ...changes in vehicle speed as the vehicles approach at and near the road humps. This study also considers the perceptions of the residents on the effects of road humps in reducing vehicle speed. The results show that the vehicle speeds at point immediately preceding and at the road hump decrease significantly but the vehicle speed increases at points immediately after the road humps. The relationship between the residential areas and the perceptions of the residents on both daytime and nighttime vehicle speed was found to be statistically significant. The perceptions of the residents on whether road humps can reduce vehicle speed were also found to be statistically significant when related with the residential areas.
This cross-sectional study aimed to determine which objective built environmental factors, identified using a virtual neighbourhood audit, were associated with cycling for transport in adults living ...in five urban regions across Europe. The moderating role of age, gender, socio-economic status and country on these associations was also investigated. Overall, results showed that people living in neighbourhoods with a preponderance of speed limits below 30km/h, many bicycle lanes, with less traffic calming devices, more trees, more litter and many parked cars forming an obstacle on the road were more likely to cycle for transport than people living in areas with lower prevalence of these factors. Evidence was only found for seven out of 56 possible moderators of these associations. These results suggest that reducing speed limits for motorized vehicles and the provision of more bicycle lanes may be effective interventions to promote cycling in Europe.
•Speed limits below 30km/h were associated with more cycling for transport.•The presence of bicycle lanes was associated with more cycling for transport.•These associations were similar across different subgroups.
Traffic calming measures (TCM) are placed in urban areas to improve road safety, and among them, vertical TCMs are widely employed. Many researches are focused on the influence of the geometry of ...each measure on speed reduction, but it is demonstrated that drivers forget its effect and speed up after it. Therefore, placing consecutive TCMs can help to maintain a safe area. However, scarce literature can be found about the adequate spacing between them. Hence, the aim of this paper is to analyze the adequate distance between TCMs. Various streets with variable distances and different vertical TCMs were evaluated in Poland and Spain, including raised crosswalks, raised intersections, speed humps and speed cushions. The intermediate point between two TCMs was selected as the place where the maximum speed is achieved. Results showed that there was a good correlation between the speeds at intermediate points and the distance between TCMs, with a determination coefficient around 0.80. For an 85th percentile of the speed under 50 km/h, a maximum distance of 200 m between TCMs is recommended, and for a value of 40 km/h, 75 m.
Abstract Walking is one of the most common sustainable modes of transportation in university campuses. To ensure its sustainability, pedestrian facilities that are safe, comfortable and reliable must ...be adequately provided. Various traffic calming measures have been introduced to enhance the safety of pedestrians. In Universiti Tun Hussein Onn Malaysia (UTHM), 6 raised crosswalks (RCW) have been installed along Persiaran Tun Ghafar Baba. This study aimed to investigate the impact of RCWs on vehicular speed reduction. Speed data were collected at each RCW. Vehicle speeds were recorded before, at and after the RCWs. Speed profiles developed indicate that the 85th percentile speed difference of RCWs were 14 – 25 km/h, which meant that the percentage of speed reduction at RCWs were remarkably high (31 – 48% reduction). Statistical tests confirmed that all RCWs yielded significant drops in speed i.e., the peak mean travelling speed versus the operational speed at the device. Furthermore, it was found that the zones of influence were between 29 – 50 m. This shows that drivers start reducing their speeds from as far as 50 m from the RCWs. Based on these findings, it can be concluded that raised crosswalks are effective in reducing speed, thus enhancing pedestrian safety while crossing as drivers tend to be more aware of their surroundings at lower speeds.
Traffic calming (TC) has been applied widely for several decades, although approaches to evaluating its effects on speeds have been inconsistent. This resulted in limited comparable and robust ...evidence to support practitioner guidance for TC design. To fill this gap and suggest best practices for the evaluation of TC effects on speeds, we performed a systematic review of 158 publications. We distilled information related to five research questions: Which measurement sensor was used? How was speed measured? Was free-flow speed considered? What was the sampling density? How were sample considerations reported? In addition to coding the studies based on these research questions, we rated them based on scientific robustness. The review confirmed the inconsistent state of evaluation practice. Most common evaluation approaches employed static detectors, low levels of control for bias (simple before-after), and unknown survey periods. The review found that the most robust evaluation practices involved multivariate before-after or cross-sectional study designs, used dynamic measurement of speeds (e.g., probe vehicles, simulations), large samples of vehicles, and more precise evaluation of speed changes using speed-distance graphs. These findings could guide more consistent and robust evaluation practice, and thus help to improve evidence-based TC guidance for creating safer and more sustainable neighborhoods.
•Q methodology was used to understand the lived experiences of traffic calming in Singapore.•We found three perspectives: Road Safety Enthusiast, Inconvenienced Users, and Implementation Critics.•The ...lived experiences and perceptions of the traffic calming measures were different across groups.•The benefits and inconveniences of these measures were felt differently across these groups.•The efficacy of Q methodology for mobility and planning related research is supported.
Traffic calming has been introduced in many cities in a bid to create more age-friendly and sustainable communities. This study uses Q methodology to understand the perspectives and experiences of residents after almost a decade since the first implementation of traffic calming measures in neighbourhoods in Singapore. In particular, we focused on the Silver Zone programme, which involves the introduction of senior-friendly road safety features in areas with a high proportion of senior residents and where there have been past road traffic injury involving seniors. With 26 participants, we identified three perspectives and termed them the Road Safety Enthusiast, Inconvenienced Users, and Implementation Critics. While their perspectives of the traffic calming measures were different, we found that all three groups broadly supported the objectives of Silver Zones. The participants were able to identify that the benefits of traffic calming go beyond protecting vulnerable populations to enhancing the liveability and overall traffic safety of their neighbourhood and community. However, the benefits and inconveniences of these measures were felt differently across these groups, which are areas for planners and policymakers to address to increase the support for traffic calming in neighbourhoods. The efficacy of Q methodology for mobility and planning related research is also supported and further discussed in the article.
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