This research conducted a two-stage assessment to investigate sun glare effects on road safety in Edmonton. The first stage developed a methodology to model sun glare occurrence, aiming to identify when and where drivers are most likely to be exposed to sun glare. Safety risks at those identified locations during sun glare periods were assessed in the second stage. By contrasting the collisions during glare and non-glare conditions, this second stage aimed to quantify the effects of sun glare on road collisions. Consequently, three major findings were concluded. First, sun glare was found to significantly contribute to collision occurrence, especially at road intersections. Second, the effects of sun glare on collision occurrence during mornings on the eastbound and evenings on the westbound were observed to be particularly worse in the spring and fall months. In fact, safety in the southbound direction was significantly affected by sun glare during most daytime hours in the main winter months (November, December, and January). Lastly, the analysis revealed that certain collision types were more likely to occur during periods of sun glare. For example, collisions due to signal violations and failing to yield to pedestrians/cyclist were more likely to occur at intersections. At mid-block locations, the proportion of collisions occurring due to improper turning and lane changes were observed to be significantly higher. Overall, the approach proposed in this research provides a holistic method to quantify the effects of sun glare on road collisions and offers additional insights into the extent by which sun glare affects road safety.

This paper describes a study undertaken to assess the speed and safety effects of reducing speed limits from 50 to 30 km/h in school zones. Mean speeds and 85th percentile speeds were reduced by 12.2 and 11.6 km/h, respectively. Speed variation was also reduced, and the speed cumulative distributions shifted to the left, indicating further reductions for all speed ranges. The safety evaluation results revealed fatal and injury collisions were significantly reduced by 45.3% and injuries to vulnerable road users were reduced by 55.3%. In fact, for every 1 km/h reduction in mean speed, fatal and injury crashes were reduced by about 4%, which is consistent with findings from previous research. Neither spatial nor temporal collision migration or spillover effects were significant factors in the analysis. Consequently, the results of this study provide strong evidence that reducing speed limits to 30 km/h in school zones can bring significant safety benefits by reducing vehicular speeds and fatal and injury crashes.

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In this study we discovered significant places in individual mobility by exploring vehicle trajectories from floating car data. The objective was to detect the geo-locations of significant places and further identify their functional types. Vehicle trajectories were first segmented into meaningful trips to recover corresponding stay points. A customized density-based clustering approach was implemented to cluster stay points into places and determine the significant ones for each individual vehicle. Next, a two-level hierarchy method was developed to identify the place types, which firstly identified the activity types by mixture model clustering on stay characteristics, and secondly discovered the place types by assessing their profiles of activity composition and frequentation. An applicational case study was conducted in the Paris region. As a result, five types of significant places were identified, including home place, work place, and three other types of secondary places. The results of the proposed method were compared with those from a commonly used rule-based identification, and showed a highly consistent matching on place recognition for the same vehicles. Overall, this study provides a large-scale instance of the study of human mobility anchors by mining passive trajectory data without prior knowledge. Such mined information can further help to understand human mobility regularities and facilitate city planning.