Participant Mobility as a Temporary Urban Transport-Energy System: Energy Use, Carbon Emissions and Low-Carbon Scenarios for the 2024 Wuhan Marathon

A mass-participation marathon assembles tens of thousands of people from many origins for a single morning, so its energy demand is dominated by a temporary transport system, not a venue. Event footprints are usually reported as one carbon total built on average travel assumptions, hiding both the heterogeneity of participant mobility and its uncertainty. This study builds an activity-based transport-energy account for the 30,000 participants in the 2024 Wuhan Marathon over nine modes and nine energy-intensity parameters, calibrates the one unobserved travel parameter against the event’s third-party certified inventory (a consistency check, not an independent measurement), and propagates sixteen parameters through 10,000 Monte Carlo runs and a Sobol decomposition. Participant mobility consumes 9097 GJ of final energy and emits 965.7 t CO2e, 32.2 kg per participant, at 33.7 g CO2e per passenger–kilometre. Aviation is 1.5% of mode users but 27.9% of energy. Travel distance carries 59% of output variance, energy intensity 18% and the much-debated aviation mode comprises 6%. Integrated operational measures cut energy by 21.8% but emissions by only 6.5%, whereas decarbonizing the regional grid cuts emissions by 56.6%: for this catchment, reducing transport energy and reducing transport carbon are not equivalent objectives.