The evidence indicates that high quality, joined-up infrastructure and behavioural interventions at trigger points in people’s lives are the most effective measures to encourage an uptake in active travel. However, the quantitative effect of these interventions is much less clear, in part due to the effect of external factors such as local weather, topography and population density. It is often noted in the literature that infrastructure is a necessary but insufficient condition on its own for a modal shift to active travel. Other factors such as the attractiveness of motor transport, environmental factors, and linked behavioural interventions all play an important part in the success of a project. In particular with walking, mixed land use and density play a more important role in determining modal share.
One of the most prevalent issues in encouraging active travel is journey time compared to motor transport. Individuals are more likely to switch to active travel modes, including mixed modes with public transport, when their journey time is reduced compared to making the trip using private motorised vehicles.
There are some interventions that are known to not be as successful or need to be carefully thought out when being implemented. Off-road cycle paths being one area that does not appear to bring an improvement in cycling modal share, and is noted as not being attractive to female cyclists. Additionally, shared spaces can have benefits for pedestrians but with poor implementation they can adversely impact others e.g. those with visual impairments.
There are substantial gaps in the literature, notably on the effect of cycling infrastructure on people with disabilities. In additional, there is a lack of evidence on the optimal mix of infrastructure and behavioural interventions, with some of this likely due to highly context-dependent nature of successful interventions.
Given the lack of quantifiable data, the responses by expert interviewees in the literature provide some of the best notes on ways to improve an intervention’s chance of success. They note that the most successful projects are those with a minimum term of five years, with stop-start funding being associated with poor results. They also note that while the size of the revenue spend is not as important, it is imperative that all capital projects come with at least some revenue spend. Finally they note that cycle infrastructure should be built as a comprehensive and continuous network and not as discrete and disconnected routes. If it is not possible to build a comprehensive network it would be better to invest the money in revenue spend to create a groundswell of support for cycling so that when the infrastructure is finally built the uptake will be a lot quicker.