Shifting towards healthier transport: carrots or sticks? Systematic review and meta-analysis of population-level interventions

London's Ultra Low Emission Zone and active travel to school: a qualitative study exploring the experiences of children, families and teachers

OBJECTIVE

Taking a qualitative approach, we aimed to understand how London's Ultra Low Emission Zone (ULEZ) might work to change behaviour and improve health in the context of the school journey.

DESIGN

Primary qualitative study embedded within an existing natural experimental study.

SETTING

A population-level health intervention implemented across London.

PARTICIPANTS

Purposive sampling was used to recruit children (aged 10-11 years) from ethnically and socioeconomically diverse backgrounds within an existing cohort study, Children's Health in London and Luton.

METHODS

In-person and online interviews were conducted with 21 families and seven teachers from the children's schools between November 2022 and March 2023. Verbatim transcripts were analysed drawing on Braun and Clarke's reflexive thematic analysis and guided by realist evaluation principles to identify contexts, mechanisms and outcomes using NVivo.

RESULTS

Common context, mechanism, outcome (CMO) configurations were identified reflecting congruent narratives across children, parents and teachers, for example, current active travellers (context) reported reductions in pollution (mechanism) leading to improvements in health, including alleviated symptoms of asthma (outcome). These CMOs were broadly captured by two themes: (i) how you travelled before the ULEZ matters: the impact of travel mode on experiences of the ULEZ and (ii) your context matters: the role of socioeconomic position in experiences of the ULEZ. Participants highlighted the potential for the ULEZ to positively impact their choice of travel mode to school, experiences of the journey and their health. However, the impact of the ULEZ differed inequitably by journey length, travel mode before implementation and access to reliable and affordable public transport.

CONCLUSIONS

The capacity for the ULEZ to both narrow and exacerbate inequities across different travel contexts suggests when developing such schemes, more emphasis needs to be placed on providing accessible and affordable alternatives to driving.

Unpacking mobility cultures: a review of conceptual definitions and empirical approaches

While "Mobility Culture" is an emerging concept in transport science and policy, it is often defined and applied in different ways. We conducted a systematic literature review focusing on the definitions of the concept and how it has been approached empirically. We found that definitions of Mobility Culture are heterogeneous, often indirect and implicit, or missing entirely. We assigned papers to five definition groups based on similarity: (1) Objective and subjective characteristics, (2) subjective-only characteristics, (3) social groups and communities, (4) normative-sustainable notions of future transportation, and (5) papers lacking definitions. Among empirical papers, we identified three broader approaches: Comparative (e.g. city typologies or pre-and-post relocation studies), single-culture (e.g. place-specific mode choice, local discourses) and intervention studies. We discuss the suitability of these approaches for different research goals and how they relate to the definition groups. Overall, we observe a lack of conceptual clarity in the Mobility Culture discourse, which is also reflected in the frequent mismatch of definitions and empirical operationalisations. We recommend that future Mobility Culture definitions consistently acknowledge the phenomenon's (i) complexity and multidimensionality, (ii) the relational character among its dimensions and attributes, and (iii) its sensibility for social and geographical differences.

The co-benefits of active travel interventions beyond physical activity: a systematic review

Active travel is a widely recognised strategy for promoting active living but its co-benefits beyond increasing physical activity, such as broader health, environmental, and social benefits, have rarely been synthesised. We conducted a systematic review to examine the co-benefits of active travel interventions. Following a preregistered protocol (PROSPERO CRD42022359059), we identified 80 studies for the search period from Jan 1, 2000, to Sept 13, 2022. Across studies, there was consistent evidence that active travel interventions offered co-benefits beyond physical activity. Particularly, 25 (71%) of 35 studies favoured improved safety outcomes, 20 (67%) of 30 showed improved health, 17 (85%) of 20 supported economic benefits, 16 (84%) of 19 highlighted improved transport quality, 12 (92%) of 13 showed environmental benefits, and four (80%) of five documented social benefits. Despite the overall low-certainty evidence, mostly limited by the quasi-experimental design and natural-experimental design of many of the studies, active travel interventions offer unique opportunities to engage stakeholders across sectors to jointly address major societal issues, such as physical inactivity, traffic safety, and carbon emissions. This evidence can inform the design, implementation, and evaluation of active travel interventions.

Children's Health in London and Luton (CHILL) cohort: a 12-month natural experimental study of the effects of the Ultra Low Emission Zone on children's travel to school

BACKGROUND

The Ultra-Low Emission Zone (ULEZ), introduced in Central London in April 2019, aims to enhance air quality and improve public health. The Children's Health in London and Luton (CHILL) study evaluates the impact of the ULEZ on children's health. This analysis focuses on the one-year impacts on the shift towards active travel to school.

METHODS

CHILL is a prospective parallel cohort study of ethnically diverse children, aged 6-9 years attending 84 primary schools within or with catchment areas encompassing London's ULEZ (intervention) and Luton (non-intervention area). Baseline (2018/19) and one-year follow-up (2019/20) data were collected at school visits from 1992 (58%) children who reported their mode of travel to school 'today' (day of assessment). Multilevel logistic regressions were performed to analyse associations between the introduction of the ULEZ and the likelihood of switching from inactive to active travel modes, and vice-versa. Interactions between intervention group status and pre-specified effect modifiers were also explored.

RESULTS

Among children who took inactive modes at baseline, 42% of children in London and 20% of children in Luton switched to active modes. For children taking active modes at baseline, 5% of children in London and 21% of children in Luton switched to inactive modes. Relative to the children in Luton, children in London were more likely to have switched from inactive to active modes (OR 3.64, 95% CI 1.21-10.92). Children in the intervention group were also less likely to switch from active to inactive modes (OR 0.11, 0.05-0.24). Moderator analyses showed that children living further from school were more likely to switch from inactive to active modes (OR 6.06,1.87-19.68) compared to those living closer (OR 1.43, 0.27-7.54).

CONCLUSIONS

Implementation of clean air zones can increase uptake of active travel to school and was particularly associated with more sustainable and active travel in children living further from school.

Understanding how and why travel mode changes: analysis of longitudinal qualitative interviews

BACKGROUND

Encouraging alternatives to the car such as walking, cycling or public transport is a key cross-sector policy priority to promote population and planetary health. Individual travel choices are shaped by individual and environmental contexts, and changes in these contexts - triggered by key events - can translate to changes in travel mode. Understanding how and why these changes happen can help uncover more generalisable findings to inform future intervention research. This study aimed to identify the mechanisms and contexts facilitating changes in travel mode.

METHODS

Prospective longitudinal qualitative cohort study utilising semi-structured interviews at baseline (in 2021), three- and six-month follow up. Participants were residents in a new town in Cambridgeshire, UK, where design principles to promote walking, cycling and public transport were used at the planning stage. At each interview, we followed a topic guide asking participants about previous and current travel patterns and future intentions. All interviews were audio recorded and transcribed. Data analysis used the framework approach based on realist evaluation principles identifying the context and mechanisms described by participants as leading to travel behaviour change.

RESULTS

We conducted 42 interviews with 16 participants and identified six mechanisms for changes in travel mode. These entailed increasing or reducing access, reliability and financial cost, improving convenience, increasing confidence and raising awareness. Participants described that these led to changes in travel mode in contexts where their existing travel mode had been disrupted, particularly in terms of reducing access or reliability or increasing cost, and where there were suitable alternative travel modes for their journey. Experiences of the new travel mode played a role in future travel intentions.

IMPLICATIONS

Applying realist evaluation principles to identify common mechanisms for changes in travel mode has the potential to inform future intervention strategies. Future interventions using mechanisms that reduce access to, reduce reliability of, or increase the financial cost of car use may facilitate modal shift to walking, cycling and public transport when implemented in contexts where alternative travel modes are available and acceptable.

Equity impacts of cycling investment in England: A natural experimental study using longitudinally linked individual-level Census data

Background

Cycling is beneficial for health and the environment but the evidence on the overall and differential impacts of interventions to promote cycling is limited. Here we assess the equity impacts of funding awarded to support cycling in 18 urban areas between 2005 and 2011.

Methods

We used longitudinally linked 2001 and 2011 census data from 25,747 individuals in the Office for National Statistics Longitudinal Study of England and Wales. Logistic regression was used to assess the impacts of funding on commute mode as the interaction between time and area (intervention/comparison) in individual-level difference-in-difference analyses, adjusting for a range of potential confounding factors. Differential impacts were examined by age, gender, education and area-level deprivation, and uptake and maintenance of cycling were examined separately.

Results

Difference-in-difference analyses showed no intervention impact on cycle commuting prevalence in the whole sample (AOR = 1.08; 95% CI 0.92, 1.26) or among men (AOR = 0.91; 95% CI 0.76, 1.10) but found an intervention effect among women (AOR = 1.56; 95% CI 1.16, 2.10). The intervention promoted uptake of cycling commuting in women (AOR = 2.13; 95% CI 1.56, 2.91) but not men (AOR = 1.19; 95% CI 0.93, 1.51). Differences in intervention effects by age, education and area-level deprivation were less consistent and more modest in magnitude.

Conclusions

Living in an intervention area was associated with greater uptake of cycle commuting among women but not men. Potential gender differences in the determinants of transport mode choice should be considered in the design and evaluation of future interventions to promote cycling.

A qualitative study of active travel amongst commuters and older adults living in market towns

BACKGROUND

Being physically active is associated with better health, but rates of physical inactivity are high amongst adults in England. Active travel, defined as making routine journeys in physically active ways, has been identified as a potential solution. There is a lack of research into how modal shift towards active travel can be encouraged in market towns. The aims of the current study are to understand how new cycling and walking infrastructure and community activation projects might support modal shift to active travel amongst commuters and older adults in market towns.

METHODS

This was a qualitative study using focus groups, 'go-along' interviews, and in-depth interviews as the main methods of data collection. Thirty-three participants (12 commuters and 21 older adults) took part across six focus groups. Eight of these also completed a go-along interview (4 walking, 4 cycling). Data were analysed using the Framework method of thematic analysis.

RESULTS

Market towns have existing advantages for active travel, being relatively compact with most routine destinations within easy reach. The barriers to active travel faced by older adults and commuters in market towns are similar to those in cities; poor infrastructure remains the key barrier. Poorly maintained paths are hazardous for older pedestrians, and low-or-no lighting and lack of well-connected, delineated cycle routes deter both commuters and older adults. One factor which does appear qualitatively different to cities is participants' perception that the social norms of cycling differ in market towns.

CONCLUSIONS

Policies to promote active travel in market towns are most likely to be effective when they include measures targeted at both individual behaviour change and population level measures like large-scale infrastructure improvements. Initiatives to change the social norms around cycling may be required to increase active travel rates.