EPSRC DLA: Compliance and Public Attitudes to Lower Urban Speed Limits: Evidence from the Welsh 20mph Policy

PGR-P-2448

Key facts

Type of research degree: PhD
Application deadline: Tuesday 31 March 2026
Project start date: Thursday 1 October 2026
Country eligibility: UK only
Funding: Funded
Source of funding: Research council
Supervisors: Dr Chiara Calastri
Additional supervisors: Prof. Robin Lovelace, Dr Zahara Batool

<h2 class="heading hide-accessible">Summary</h2>

One full scholarship is available in the Institute for Transport Studies in 2026/27. This scholarship is open to UK applicants and covers fees plus maintenance. The Institute for Transport Studies invites applications from prospective postgraduate researchers who wish to commence study for a PhD in the academic year 2026/27 Institute for Transport Studies EPSRC DLA Scholarship.

<h2 class="heading hide-accessible">Full description</h2>

Background In September 2023, Wales introduced a nationwide default 20 mph speed limit on restricted roads, representing the first policy of this scale in the UK and one of the few cases internationally for which high-quality observational data are available. Early monitoring (Transport for Wales, 2024) shows clear reductions in average vehicle speeds, but levels of compliance vary substantially across locations and over time. At the same time, public debate surrounding the policy highlights uncertainty about its legitimacy, fairness, and acceptability (Quddus et al., 2025). These issues have direct implications for enforcement strategies, policy adjustment, and decisions about whether similar measures should be sustained or considered elsewhere in the UK. While international research demonstrates that lower urban speed limits can reduce speeds and improve safety, policymakers currently lack evidence on how behavioural compliance and public attitudes interact following a major policy change. Existing studies typically examine short-term behavioural outcomes (such as mean speeds or collisions) or public opinion in isolation. As a result, there is limited empirical evidence to inform whether observed compliance reflects durable behavioural change, short-term enforcement effects, or evolving social norms. This gap constrains the ability of governments to design cost-effective, publicly legitimate speed management policies and to assess their transferability across different contexts. The Welsh 20 mph policy provides a timely opportunity to address this evidence gap. The availability of detailed administrative traffic data alongside established national attitude surveys enables analysis of how compliance patterns and attitudes towards road safety, speeding, and enforcement evolve over time. By treating the Welsh policy as a behavioural natural experiment, this project focuses on the relationship between observed compliance trajectories and attitudinal change, generating evidence directly relevant to policy decisions about the long-term sustainability of lower urban speed limits. Hypothesis Compliance with lower urban speed limits reflects not only road and traffic characteristics but also evolving public attitudes, social norms, and perceptions of legitimacy. Attitudinal change may lag behind behavioural change initially, but sustained compliance is more likely where attitudes towards safety and enforcement become more favourable over time. These dynamics vary across places and population groups. Aims The primary aim of this PhD is to understand how public attitudes and behavioural compliance evolve and vary across social and spatial dimensions following the introduction of lower urban speed limits, using the Welsh 20 mph policy as a case study. The project focuses on the relationship between observed compliance trajectories and attitudes towards road safety, speeding, and enforcement, with the objective of informing the design and long-term sustainability of speed management policies. Objectives - To characterise spatial and temporal patterns of compliance with the Welsh 20 mph speed limit using existing speed and collision datasets. - To analyse trends in public attitudes towards road safety, speeding, and enforcement using longitudinal and repeated cross-section survey data. - To examine the temporal relationship between attitudinal change and observed compliance following the policy introduction. - To assess how these relationships vary across local contexts and population groups within Wales. The project will analyse compliance and attitudinal change using existing administrative and survey data. Compliance will be examined using Transport for Wales speed monitoring datasets, vehicle speed data from the Ordnance Survey MRN product, and collision records from the Department for Transport’s STATS19 database. Together, these sources enable detailed analysis of how speed distributions and indicators of compliance vary across locations and over time within Wales. Public attitudes towards road safety, speeding, and enforcement will be analysed using established national survey datasets, including the National Travel Attitudes Study and the British Social Attitudes survey. These data provide longitudinal and repeated cross-section evidence on transport-related attitudes and social norms, enabling examination of whether attitudinal trajectories align with, precede, or lag behind observed changes in compliance. The use of these existing datasets ensures the project remains feasible within a PhD timeframe while allowing robust behavioural analysis. Bayesian statistical methods will be used to integrate compliance and attitudinal evidence within a coherent analytical framework (Er et al., 2025). This approach supports transparent uncertainty quantification and hierarchical modelling of variation across sites, time periods, and population groups, which is particularly important when combining administrative and survey data sources. While the core analysis is centred on Wales, the availability of Great Britain–wide attitude surveys allows broader trends to be explored where appropriate. These comparisons are intended to provide interpretative context and to assess whether observed changes in Wales differ from longer-term national patterns, rather than forming a required component of the core thesis. Such extensions enhance the policy relevance of the work without expanding the project’s primary scope. The studentship will provide training in behavioural modelling, Bayesian statistics, and the analysis of large-scale transport and survey datasets. The research will generate evidence directly relevant to decisions about the sustainability, communication, and public legitimacy of lower urban speed limits, while equipping the student with highly transferable analytical and policy-facing skills. References Er, S., Briz-Redon, Á., Salau, S., Lovelace, R., 2025. Modelling of Traffic Collisions at Road Intersections in Cape Town, South Africa: A Bayesian Spatio-Temporal Approach. Appl. Spatial Analysis 18, 93. https://doi.org/10.1007/s12061-025-09703-0 Quddus, M., Theofilatos, A., Feng, M., Elvik, R., 2025. Evaluating the safety and speed impacts of the 20mph speed limit in the UK: Evidence and insights. Accident Analysis & Prevention 221, 108210. https://doi.org/10.1016/j.aap.2025.108210 Transport for Wales (2024) Default 20mph speed limit on restricted roads: National monitoring report (September 2023 - April 2024). Available at: https://tfw.wales/national-monitoring-report-september-2023-april-2024 (Accessed: 4 December 2025).

<h2 class="heading">How to apply</h2>

Formal applications for research degree study should be made online through the <a href="https://www.leeds.ac.uk/research-applying/doc/applying-research-degrees">University's website</a>. Please state clearly in the research information section that the research degree you wish to be considered for is Compliance and Public Attitudes to Lower Urban Speed Limits: Evidence from the Welsh 20mph Policy as well as <a href="https://environment.leeds.ac.uk/transport/staff/921/dr-chiara-calastri">Dr Chiara Calastri</a> as your proposed supervisor. If English is not your first language, you must provide evidence that you meet the University's minimum English language requirements (below). As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Across all Faculties we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+ and people with disabilities. Applicants will always be selected based on merit and ability.

<h2 class="heading heading--sm">Entry requirements</h2>

Applicants to this project in the Institute for Transport Studies should have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in transport studies, engineering, economics, statistics, environmental analysis or a related field.

<h2 class="heading heading--sm">English language requirements</h2>

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<h2 class="heading">Funding on offer</h2>

We are offering a fully funded scholarship to study the project Compliance and Public Attitudes to Lower Urban Speed Limits: Evidence from the Welsh 20mph Policy, at the Institute for Transport Studies, University of Leeds for one UK status candidate. The funding covers UK tuition fees as well as UKRI matched stipend (currently £20,780 on 2025/26) per year, subject to satisfactory progress. Eligibility Criteria Applicants must be eligible for UK (Home) fees/funding. If you are unsure whether you are eligible for UK fees/funing, please see our <a href="https://www.leeds.ac.uk/undergraduate-fees/doc/fee-assessment">fee assessment page.</a>

<h2 class="heading">Contact details</h2>

For further project information please contact Dr Chiara Calastri: <a href="mailto:C.Calastri@leeds.ac.uk">C.Calastri@leeds.ac.uk</a> For application queries and guidance, please conact Environment PGR Admissions: ENV-PGR@leeds.ac.uk