With the longstanding overrepresentation of seniors in pedestrian injuries and fatalities, added to the prevalence of North-American ageing population, there is a sense of urgency for public health and transport planners to better understand the conditions surrounding senior injury risk. However, planners and practitioners are still challenged by a North-American built environment often optimized for vehicles rather than active and ageing road users. Researchers, on the other hand, still do not fully understand the nuances between younger and older injury factors, and particularly the effect of senior pedestrian exposure on their injury risk. 
The primary research question in this thesis seeks to determine if senior injury factors at signalized intersections differ from those of the younger and to what extent? In a secondary fashion, this thesis explores the definition of an optimal built environment for pedestrian safety in an ageing society. In addition, it explores determining whether or not subpopulation models are more inclusive. Chapter 4 presents an injury regression analysis comparing 479 younger and 107 older pedestrian injuries that occurred at 191 signalized intersections in Montreal, a study deemed “practice ready” that was presented at the 2015 Transportation Research Board (TRB) annual meeting. 
Among other results, the center median refuge was found to reduce injury probability in seniors by 70%, implying that it has the potential to be a strong countermeasure in an ageing society. Results of this research revealed nuances between younger and older injury factors, and suggest that the optimal built environment for pedestrian safety of an older society may indeed differ from one optimized for the younger. In addition to being more inclusive, findings suggest that without subpopulation models, safety or health performance indicators of senior pedestrians may be overlooked.