Perceived barriers
The mean number of perceived barriers was 3.26 (SD: 2.83) for the parents of children, 2.49 (SD: 2.86) for the parents of adolescents, and 1.55 (SD: 2.43) for adolescents themselves. The parents of adolescents perceived significantly fewer barriers than the parents of children (The number of perceived barriers reported by parents and by adolescents showed significant inverse correlations with AST in the univariate models. In the univariate models for children ≤ 10 years, most barriers exhibited a negative correlation to AST. Only the way is too boring, too exhausting, and having no desire to walk/cycle were not associated with the outcome (Table Models for children (≤ 10 years) analyzing correlations between active school transport and sociodemographic variables, distance between home and school, and perceived barriers (based on parental answers). OR = exp(ß) High socioeconomic status(ref.: low to middle) Distance between home and school(in 100 m) for very short distances Distance between home and school(in 100 m) for longer distancesThe answering options the path is too dangerous (positive correlation), too much traffic, no other children, too heavy load to carryIn the adolescent sample, the route being too exhausting or too boring were the only barriers not showing any significantly negative correlation with AST in the univariate analyses using the parental answers. The multivariate analysis using the parental answers showed significantly negative correlations between AST and the following perceived barriers: too heavy load to carry, number of perceived barriers, and longer distance (only for adolescents not living in the immediate surroundings of their school). Examining the adolescents’ answers, crime was the only barrier that did not show a significantly negative association with AST in the univariate models (Table Models for adolescents (> 10 years) analyzing correlations between active school transport and sociodemographic variables, distance between home and school, and perceived barriers (separate models based on parental or adolescents' answers). OR = exp(ß) High socioeconomic status(ref.: low to middle)