A move to bicycles, like in Copenhagen, would reduce CO2 emissions and save millions in healthcare.

Science Editorial, June 9 (EFE).- A study based on the analysis of transportation modes in more than 11,500 cities around the world concludes that making streets more accessible to pedestrians and bicycles would drastically reduce greenhouse gas emissions and save public health billions of dollars.

Specifically, if each city increased its cycling network to the level of Copenhagen (Denmark), greenhouse gas emissions from private cars would be reduced by 6% and public health benefits would reach €381 billion per year, "considerable" benefits, the study's authors point out.

The study, details of which were published Monday in the journal Proceedings of the National Academy of Sciences, takes as its reference European cities such as Amsterdam (Netherlands) and Copenhagen, famous for their high proportion of active travel, where nearly half of all trips are made by bicycle or on foot.

Until now, the lack of data from many countries, particularly the United States, has limited the ability to develop policies to promote active transportation in other parts of the world, the authors argue.

But promoting the use of active transportation (walking and cycling) not only has many benefits for physical and mental health, but would also help reduce the number of pedestrian accidents, especially in places like India and the United States, where pedestrian fatality rates are high or rising rapidly, the authors point out.

41% of the world's urban population

To conduct the study, Adam Millard-Ball of the University of California, San Francisco, and his team analyzed 2023 transportation data from 11,587 cities—more than 14 times more than previous research—across 121 countries and six continents, representing nearly 2 billion people, or about 41 percent of the world's urban population.

The study suggests that the success of cities like Amsterdam and Copenhagen, where approximately half of all trips are made by active means, is driven by high population density, which allows more destinations to be reached on foot or by bicycle, and by urban design, which creates walk-oriented uses, such as shops and window displays.

But the high proportion of active modes of transport is also the result of policy and infrastructure decisions such as separate cycle lanes and safe pedestrian crossings, and restricting car use through parking management and other policies, the study highlights.

To conduct this analysis, the authors used hierarchical Bayesian models and found that increasing population density in cities was directly related to increased walking, with each additional kilometer of bike lane associated with approximately 13,400 additional kilometers of bicycle trips.

Furthermore, according to the study's simulations, if all cities increased the extent of their bike lane networks to the level of Copenhagen, the reduction in greenhouse gas emissions from private vehicles in cities would be cut by nearly 6% and could save €381 billion in public health costs annually.

The study also found that less rugged cities had a higher proportion of bicycle commutes, and that higher gasoline prices favored both cycling and walking.

Furthermore, the study concluded that harsh winter and summer climates are not a major obstacle to walking and cycling for most of the year and that doing so has significant benefits for people's health, both physical and mental (cycling reduces all-cause mortality by 10 to 11%).

For the authors, the results highlight that there is no single urban planning model, but that all cities could implement appropriate strategies to increase active travel and replace motor vehicles with active transportation.