Nonlinear effects of transit on children’s activity range: Mobile phone data insights

Public transit accessibility plays a pivotal role in shaping children’s mobility, yet it remains underexplored due to challenges in capturing children’s actual activity patterns. This study adopts anonymized mobile phone data to address these gaps. By identifying complete travel activities among children mobile phone users, the study examines nonlinear relationships between three transit modes (i.e. walk, bus and metro) and children’s activity range across different levels within home and school contexts. Results show that transit accessibility’s importance increases as children’s activity range expands, particularly around schools, with road density playing a dominant role. While transit accessibility positively influences moderate activity ranges, negative associations emerge at extensive levels. Enhanced transit accessibility most benefits children from lower-cost neighborhoods. The findings identify effective thresholds for urban transportation systems, offering actionable insights for child-centered transport planning, and highlighting the priority of equitable public transit and school-focused planning strategies to support children’s mobility and well-being.