Le carrefour giratoire est un aménagement routier qui a connu un fort succès au cours des années 1970 et est désormais pratique courante en Europe grâce à ses performances en termes de capacité et de sécurité. Néanmoins, ce concept d’ingénierie est d’usage beaucoup moins répandu dans le reste du monde et, notamment, en Amérique du Nord où la population reste circonspecte à son propos. Pourtant, lors de mises en application, les préjugés négatifs se transforment rapidement en opinion favorable. De plus, lorsque l’implantation est précédée d’une planification et d’une conception minutieuses, accompagnée d’une campagne de communication efficace, le carrefour giratoire peut être adapté à l’environnement et aux conducteurs nord-américains. De nombreux guides proposent un cadre pour la conception des carrefours giratoires, mais il n’existe pas encore de normes établies. Les efforts de recherche actuels visent à mieux comprendre le fonctionnement de ces aménagements routiers afin de pouvoir tirer des règles de conception plus efficaces et pertinentes.

Traffic control systems are crucial for managing traffic flows. Their main function is to reduce interactions among users for safety reasons, while minimizing the travel times. Researchers often concentrate on the cycle length, whose impact on travel times is directly measurable. However, the choice of the signal pattern may also have a great potential to reduce travel times and unsafe situations. This potential is yet to be thoroughly investigated. In this work, we are interested in comparing different signal patterns in terms of the number of potential conflicts and delay time for both drivers and pedestrians. To this end, we first select three commonly adopted signal patterns, namely the Exclusive Pedestrian Phase (EPP), the Leading Through Interval (LTI) and the Two-Way Crossing (TWC). We then generalize existing methods for measuring user delay and safety for these three signal patterns. Moreover, we investigate a hypothetical hybrid pattern obtained by dynamically adapting the signal pattern to real-time data. The proposed methodology is applied to a case study considering an isolated intersection in Montreal, Canada. We perform computational experiments geared towards determining the best pattern according to ad hoc performance indicators and user flows. Results show that the EPP and LTI patterns generally perform better than TWC. EPP generally outperforms LTI when measuring the number of potential conflicts, while LTI outperforms EPP when considering delay times. Furthermore, the hypothetical hybrid pattern shows a positive but overall limited impact regarding both delay times and number of potential conflicts.

Environmental nuisances (such as greenhouse gases and noise) may be generated during the use phase of the pavement life cycle, with these known to significantly affect the environment. However, no attempt has yet been made to gather information concerning the processes involved in the generation of environmental impacts, and to evaluate them. To address this issue, this paper reviews the knowledge base and relevant methods relating to environmental impact assessment and pavement management. It then presents a conceptual model, integrating impact pathway approach and life cycle cost analysis principles and providing a comprehensive framework for quantification and incorporation of environmental impacts into pavement management. This study shows that pavement management influences environmental impacts occurring during the use phase of the pavement life cycle. It establishes causal links between pavement management and nuisance generation, between nuisances and their impact on receptors, and finally between these impacts and their costs. This study also suggests that incorporating environmental impacts into pavement management systems is feasible and describes how existing and future methodologies and tools may be integrated to support this incorporation. Finally, this study underlines that the inaccuracy of current knowledge and data limits the scope of this conceptual model to network-level decisions.