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Introduction: Being physically active has multiple health benefits and contributes to the reduction of co-morbidities and mortality from chronic diseases. Active transport (walking and cycling) contributes to population health by enabling physical activity. We developed a simulation model to measure health impacts of transport scenarios for Melbourne, Australia. Our aim was to demonstrate active transport health impacts and support the materialization of policies for healthy cities and people. The model measures health impacts of increased physical activity from replacing short car trips for any purpose or for commuting under 5 km by walking and cycling. Methods: We developed a micro-simulation model of physical activity and disease risk in combination with the well-established proportional multi-state life table model. We quantified life course health including health adjusted-life years, life years, new cases of diseases prevented, and deaths prevented for 14 chronic diseases associated with physical inactivity for the adult population of people from Melbourne, Australia in 2017. Results: Over the life course of the Melbourne adult population of 3.6 million people in 2017, gains in health-adjusted life years ranged from 5,100 (95% Uncertainty Interval (UI) 3,700 to 6,500) for the scenario replacing commute trips by car under 1 km with walking up to 738,800 (95% UI 546,000 to 935,000) when replacing car trips under 2 km with walking and between 2 km and 5 km with cycling. We also estimated benefits in terms of reductions of new cases of diseases and deaths prevented, with the greatest gains for ischemic heart disease, stroke, Alzheimer's and other dementias and type 2 diabetes. Conclusions: We found that shifting car travel to active modes would accrue important health benefits for the 2017 Melbourne population. Our results support policies and strategies for sustainable transport planning to contribute to reduce the burden from chronic diseases and environmental impact of car-oriented cities.

Funder: National Institute for Health Research; Grant(s): GHR: 16/137/34, The literature on urban travel behaviour in Africa is sparse, limiting our understanding of how urban transport policies respond to human and planetary needs. We conducted a cross-sectional household telephone survey on 1334 participants, using a 24 h time-use diary, to investigate travel behaviour and barriers to active travel (walking and cycling) in Yaoundé, Cameroon. We found that two-thirds of all participants reported at least one trip; the median (IQR) numbers of trips per capita and per participant with trips were 2 (0−3) and 2 (2−3), respectively. The main trip modes were shared taxi (46%), walking (27%), private cars (11%), and motorcycle taxis (10%), with 25%, 56%, and 45% of all participants reporting the use of active, motorised, and public transport, respectively. The mean (IQR) trip duration was 48 (30−60) min; for participants who reported trips, the daily overall and active travel durations were 121 (60−150) and 28 (0−45) min, respectively. Women were less likely to travel, making fewer and shorter trips when they did. Participants in less wealthy households were more likely to travel. The primary barriers to both walking and cycling were the fear of road traffic injuries and the inconvenience of active travel modes. Therefore, local urban transport authorities need to improve the safety and convenience of active mobility and promote gender equity in transport. Restrictions to movements during the COVID-19 pandemic and the relatively small survey sample might have biased our results; thus, a representative travel survey could improve current estimates. More generally, high-quality research on travel behaviours and their correlates is needed in low-resource settings.

Background: The transportation sector accounts for approximately 23% of total energy-related carbon dioxide (CO2) emissions worldwide and 33% in the USA. At the same time, physical inactivity contribute to the adverse health through non-communicable diseases. If policies can increase active transport (walking and cycling) and reduce car use, they could benefit human health and environmental health but the relative impact of different approaches has been under researched. Methods: This study estimated change in all-cause mortality and CO2 emissions in greater Nashville, Tennessee (USA) for two scenarios: (a) the propensity to walk and cycle a trip of a given distance increases directly to the same levels as seen in England, and (b) walking and cycling trips increase and travel distance decrease indirectly as a result of a more compact urban form. Results: If the propensity to walk and cycle in Nashville were equal with England, about 339 deaths and about 36 ktCO2e (1%) of transportation-related CO2 emissions annually could be avoided. Compact urban form scenario could avoid 170 deaths and 370 ktCO2e (10%) of transportation-related CO2 emissions. Conclusion: In Nashville, both increasing the propensity to use active transport and more compact urban form would have notable public health gains, but a more compact form would have a much bigger effect on emissions.

Key messages • Technological, societal and nature-based solutions should work together to enable systemic change towards a regenerative society, and to deliver net-zero greenhouse gas (GHG) emissions. • Prioritise research into efficient, low-carbon and carbon-negative solutions for sectors that are difficult to decarbonise; i.e. energy storage, road transport, shipping, aviation and grid infrastructure. • Each solution should be assessed with respect to GHG emissions reductions, energy efficiency and societal implications to provide a basis for developing long-term policies, maximising positive impact of investment and research effort, and guiding industry investors in safe and responsible planning.