IMS Epidemiology Studies

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Aims

School Streets ban most cars from the roads right outside schools, at times when children arrive or leave. We wanted to find out whether School Streets help more young people to walk, cycle, scoot or skate to school. We also wanted to know whether they work the same everywhere or whether they help more in some places than others.

Why is this important?

Lots of research has found that active travel – like walking, scooting, cycling and skating – is good for our bodies and our minds. Having fewer cars on the road makes the air we breathe cleaner and might cause fewer car accidents. The point of School Streets is to have fewer cars outside schools and to encourage young people to travel actively. Lots of schools in the UK, especially in London, already have School Streets. But nobody has tested lots of School Streets at once, across the whole country, to see how well they work. Understanding how different types of School Streets work in different places means the people deciding where to put School Streets know where and how they might work best. That’s why we did this research.

What did we do?

In this part of our research, we looked at how many children used active ways (like walking, scooting or cycling) to get to and from school before and after School Street rules started. We then compared this with schools which don’t have School Street rules. We looked at:

• 166 schools with School Streets (cars banned right outside schools)

• 332 schools without School Streets (cars allowed)

We made sure to compare similar schools. The schools with and without School Streets:

• Were in similar places

• Had similar numbers of pupils

• Had similar levels of active travel before the School Street rules

What did we find?

Schools with School Streets saw more children walking, cycling, scooting or skating to and from school. There was about a 6% increase compared to schools without School Streets. This means that if you take 100 people from the school, 6 people who used to take the car to school now get there in more active ways. More young people now:

• Walked the whole way to school

• Rode bikes, scooters or skateboards all the way to school

• Got dropped off nearby and walked the rest of the way to school

This happened in lots of different places and types of schools.

Why is this helpful?

School streets cost money to set up. Our research shows that they do work, so it might be worth spending that money to set up School Streets at more schools, to try to keep children stay active and safe.

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Mixed-methods research into population health interventions is typically comprised of multiple distinct but related components, using different methods and data sources, which must be integrated to provide holistic insight into intervention effects and how they come about. Theory-based methods can be used to integrate findings and answer questions of causation. It can be difficult to identify which of several possible methods is best suited to a project, and the extant literature on how to resolve this issue in relation to population health interventions is scant.

In this article, we explore how a specific type of process tracing (theory testing) and congruence analysis could be used in our evaluation of schemes that restrict motorised vehicle access to streets outside UK schools during drop-off and pick-up times. We explore whether either, or both, of these methods would be suited to our evaluation, which uses national quantitative data and qualitative data in specific case study areas.  We provide an example of how they could be applied to a population health intervention and recommendations for others seeking to use these methods in evaluation of population health interventions.

In the case of the two methods tested, it seemed congruence analysis provided a better option than theory testing process tracing because we are interested in understanding the many possible ways by which traffic restriction schemes may alter travel behaviour. We value a broader evaluation over one which is narrower but can make stricter causal claims. Theory testing process tracing may be a better fit for research questions with a narrower hypothesis or where only one causal pathway is the focus. Using both in combination may be a possible option, where congruence analysis is used to identify likely candidate pathway(s) which could be further examined using process tracing or using other types of process tracing which seek the best possible explanation.

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Population health interventions may change physical, social or fiscal environments to shift health behaviours and often operate within a complex system of interacting factors. Systems methods are frequently suggested as a way to provide an overview of the interactions that determine behaviours or actions and may help to understand how or why interventions might (or might not) change health. However, there are few examples of how these methods have been used in empirical evaluations of public health interventions.

We describe our application of a qualitative complex systems approach to evaluate a population health intervention: traffic restriction schemes, often referred to as School Streets, where motor vehicle access outside schools is restricted at pick-up and drop-off times. We intend to use systems methods across our evaluation; here we describe how we use these methods to build theory. Following the five-step approach outlined by Alvarado et al., (2023), we produced research propositions, systems archetypes and a causal loop diagram to understand the underlying system in which traffic restriction schemes are implemented and their potential impact on school-based active travel. In bringing together diverse and multi-disciplinary evidence from different stakeholders we identified unanticipated systems interactions such as increased initial tensions between active travel modes (e.g. cyclists vs pedestrians). Using causal loop diagrams and systems archetypes, we developed research propositions focused on funding and implementation, safety, habit formation and the potential for unintended consequences.

Taking a complex systems approach has deepened our understanding of how traffic restriction schemes interact with their broader context and helped us develop a guiding theoretical framework for our ongoing evaluation. We intend this work to stimulate discussion, offer insights for future evaluations of population-level health interventions, and encourage public health researchers to adopt systems methods in their own evaluations.

Read full pre-print here.

 Active travel to and from schools offers important health and environmental benefits, yet car use remains dominant, contributing to congestion, pollution and safety risks. Schemes to restrict private motor vehicles are increasingly being implemented around schools to address these issues, but evidence on how they might work to impact the school journey across different contexts is limited.

We aimed to explore the mechanisms through which schemes might influence school travel behaviour and how the impacts vary across different contexts.

In-person walk-along and online interviews were conducted with 24 families, seven teachers and four local authority representatives across three areas (Perth and Kinross, Haringey and Sheffield) in Great Britain between September 2024 and April 2025. Ethnographic observations were also carried out. Transcripts were analysed drawing on Braun and Clarke’s reflexive thematic analysis, guided by realist evaluation principles and ethnographic observations to identify contexts, mechanisms and outcomes using NVivo.

Common context-mechanism-outcome (CMO) configurations were identified reflecting congruent narratives across participants. For example, for families who were already travelling actively (Context), reduced through-traffic and congestion functioned as mechanisms (Mechanism), leading to calmer, safer and more sociable environments. These changes improved the quality, safety and overall experience of the school journey (Outcome). CMOs were broadly captured by two themes: i) considering change and adapting routines: how families responded to schemes, and ii) navigating challenges and building momentum: how schemes evolved in practice. Participants highlighted the potential for schemes to promote active travel to school, improving experiences of the journey and their health. By situating these schemes within their wider social and policy context, we underscore the importance of supportive infrastructure, meaningful consultation, and framing around children’s health and safety to maximise impact and public acceptability.

The capacity for schemes to promote healthier and more sustainable school travel, while also generating unintended consequences, suggests that effective implementation requires supportive infrastructure, sustained community engagement and alignment with broader policy priorities.