Aiming to reduce pollutant emissions, bicycles are regaining popularity specially in urban areas. However, the number of cyclists' fatalities is not showing the same decreasing trend as the other traffic groups. Hence, monitoring cyclists' data appears as a keystone to foster urban cyclists' safety by helping urban planners to design safer cyclist routes. In this work, we propose a fully image-based framework to assess the rout risk from the cyclist perspective. From smartphone sequences of images, this generic framework is able to automatically identify events considering different risk criteria based on the cyclist's motion and object detection. Moreover, since it is entirely based on images, our method provides context on the situation and is independent from the expertise level of the cyclist. Additionally, we build on an existing platform and introduce several improvements on its mobile app to acquire smartphone sensor data, including video. From the inertial sensor data, we automatically detect the route segments performed by bicycle, applying behavior analysis techniques. We test our methods on real data, attaining very promising results in terms of risk classification, according to two different criteria, and behavior analysis accuracy.
In the past few years, sensing human activity has become ubiquitous and traffic has been no exception. In this vein, several studies have focused on collecting traffic data to monitor road conditions @cite_30 @cite_24 , roadway operation @cite_11 @cite_12 , and assessing driving experience @cite_22 @cite_32 @cite_34 . However, the large majority of these works @cite_30 @cite_32 @cite_22 @cite_34 @cite_24 target motorized vehicles as these are still dominant in today's traffic volume. Nevertheless, bicycle usage has recently grown mainly in urban areas @cite_15 ; and perhaps the marginal decrease of cyclists' fatality in comparison to all other road groups @cite_17 is a by-product of this trend. These facts have raised awareness to cyclists' safety, and the research community is starting to give more and more attention to this issue (see, for example, the February 2017 Safety Science special issue on Cycling Safety).
@cite_30 @cite_22 @cite_32 @cite_17 @cite_24 @cite_15 @cite_34 @cite_12 @cite_11
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In recent years, the modal share of cycling has been growing in North American cities. With the increase of cycling, the need of bicycle infrastructure and road safety concerns have also raised. Bicycle flows are an essential component in safety analysis. The main objective of this work is to propose a methodology to estimate and map bicycle volumes and cyclist injury risk throughout the entire network of road segments and intersections on the island of Montreal, achieved by combining smartphone GPS traces and count data. In recent years, methods have been proposed to estimate average annual daily bicycle (AADB) volume and injury risk estimates at both the intersection and segment levels using bicycle counts. However, these works have been limited to small samples of locations for which count data is available. In this work, a methodology is proposed to combine short- and long-term bicycle counts with GPS data to estimate AADB volumes along segments and intersections in the entire network. As part of the validation process, correlation is observed between AADB values obtained from GPS data and AADB values from count data, with R-squared values of 0.7 for signalized intersections, 0.58 for non-signalized intersections and between 0.48 and 0.76 for segments with and without bicycle infrastructure. The methodology is also validated through the calibration of safety performance functions using both sources of AADB estimates, from counts and from GPS data. Using the validated AADB estimates, the factors associated with injury risk were identified using data from the entire population of intersections and segments throughout Montreal. Bayesian injury risk maps are then generated and the concentrations of expected injuries and risk at signalized intersections are identified. Signalized intersections, which are often located at the intersection of major arterials, witness 4 times more injuries and 2.5 times greater risk than non-signalized intersections. A similar observation can be made for arterials which not only have a higher concentration of injuries but also injury rates (risk). On average, streets with cycle tracks have a greater concentration of injuries due to greater bicycle volumes, however, and in accordance with recent works, the individual risk per cyclist is lower, justifying the benefits of cycle tracks. Abstract Urban areas in North American cities with positive trends in bicycle usage also witness a high number of cyclist injuries every year. Previous cyclist safety studies based on the traditional approach, which relies on historical crash data, are known to have some limitations such as the fact that crashes need to happen (a reactive approach). This paper explores the use of GPS deceleration events as a surrogate-proactive measure and investigates the relationship between reported cyclist road injuries and deceleration events. The surrogate safety measure is defined based on deceleration values representing hard breaking situations. This work uses a large sample of GPS cyclist trip data from a smartphone application to extract deceleration rates at intersections and along segments and to explore its relationship with the number of observed injuries and validate deceleration rate (DR) as a surrogate safety measure. Using Spearman’s rank correlation coefficient, we compared the ranking of sites based on the expected number of injuries and based on DR. The ranks of expected injuries and dangerous decelerations were found to have a correlation of 0.60 at signalized intersections, 0.53 at non-signalized intersections and 0.57 at segments. Despite the promising results of this study, more granular data and validation work needs to be done to improve the reliability of the measures. The technological limitations and future work are discussed at the end of the paper. Due to economic and environmental issues, bicycles have been regaining their significance as a transportation vehicle in urban scenarios. To further drive this desirable trend, policy makers must have the tools to access current bicycle infrastructures and road safety concerns. Fundamental for this assessment is a deeper understanding of how cyclists use current infrastructures, if the cycling experience results in stressful events, and the conditions of the current infrastructure. We here introduce a new platform, SMARTcycling, that, by taking advantage of the mobile power available to a smartphone, captures and stores data from several sensors, namely an action camera, a cardio signal acquisition belt, and smartphone's Global Positioning System (GPS) coordinates. The data is further processed and, through visual cues, we access the cyclist driving events and road condition cues. SMARTcycling also detects the cyclist stress using the electrocardiograms (ECG) from the belt. We further contribute by making available a dataset containing the sensors data from 10 paths over two cities in Portugal. On this dataset, we show our initial promising results on event detection, road condition identification and stress assessment. One of the main challenges in the conduct of detailed analysis of cyclist behavior is the lack of reliable data. Collection of data through manual methods is a labor-intensive and time-consuming process. Two of the important areas of cyclist data collection are volume counts and average speed measurements. A volume count provides the basis for necessary exposure measures and conveys essential information about traffic patterns. Cyclist speed data are used for traffic control and safety studies. The application of computer vision (CV) techniques enables the collection of precise spatial and temporal measurements of road users in a resource-efficient way. This paper presents the use of a set of CV techniques for the automated collection of cyclist data. Cyclist tracks obtained from video analysis were used to perform screen line counts as well as cyclist speed measurements. The applications were demonstrated with the use of a real-world data set from a roundabout in Vancouver, British Columbia, Canada. Further analysis was conducted on the mean speed of cyclists with regard to several factors (e.g., travel path, helmet use, group size). The motivation for this research was to understand better cyclist behavior and how it varied under different conditions. Several conclusions could be drawn from the analysis of cyclist speed behavior. Group size, travel path, lane position, and helmet use were all found to affect the cyclist mean speed. Single cyclists had a slightly, but significantly, higher mean cycling speed than did group cyclists. The mean cycling speed was highest for those cyclists who used the road rather than the sidewalk. The mean cycling speed decreased for cyclists without helmets.