Pedestrian crashes are a global safety issue impacting all age groups, and despite extensive research, understanding the severity of crashes among different age groups has remained incomplete. Older and young pedestrians represent two distinct demographics with unique vulnerabilities. This paper examines the factors that impact the severity of pedestrian crashes resulting in Killed or Serious Injuries in South Australia over ten years (2012–2020) for two age groups, namely young pedestrians (age < 18) and older pedestrians (age > 65). The study employs several descriptive and analytical methods, including logistic and Classification and Regression Tree models. The findings reveal that older pedestrians are primarily involved in fatal crashes (32 %), while their young cohorts predominantly suffer from serious injuries (30 %). Young pedestrians experience more severe consequences when vehicle speeds are below 60 km/hr, but older pedestrians suffer a greater likelihood of harm at speeds beyond 60 km/hr. Age has a role in how unique elements, such as curving roadways and damp weather, affect the intensity of the impact. Young individuals are particularly drawn to motorways and one-way highways, which are prominent areas that underscore the necessity for action. Intersections, including crossroads and one-way highways, pose significant challenges for older pedestrians, underscoring the need for safety precautions. Also, there is a negative correlation between weekend crashes and log-odds of KSI compared to weekdays, which leads to lower severity for both age groups. Customizing safety protocols for distinct age cohorts is crucial for ensuring efficient crash mitigation.