DfT 20mph Evaluation Conclusions

We consider this report to be a very useful addition to the wealth of information that we have already collated in our briefing sheets. We think it beneficial to both provide a link to the Headline Report and the Detail Report.

We are particularly pleased with the  summary of "Lessons and considerations for national and local decision-makers", which very much echoes our own views on the way to implement wide-area schemes which maximise success and provide the foundation for a wide range of societal benefits and other initiatives.

Hence we have included the final sections of the Headline Report below. You may also download the MindMap which we presented to Atkins toward the end of the evaluation for comparison.

You can also access our Press Release showing our initial response.

12.5. Lessons and considerations for national decision-makers

National guidance – Based on the findings of this study, the guidance set out in DfT Circular 01/2013 remains broadly valid. This states that where there is expected to be a positive effect on road safety and a general favourable reception from local residents, traffic authorities should consider implementing area-wide 20mph limits on:

• major streets where there are, or could be significant numbers of journeys on foot, and/or where cycle movements are an important consideration, and this outweighs the disadvantage of longer journey times for motorised traffic;

• residential streets where the streets are being used by people on foot and on bicycles, there is community support, and the characteristics of the street are suitable;

and, on the assumption that the limits are generally self-enforcing and that there should be no expectation on the police to provide additional enforcement beyond their routine activity, unless this has been explicitly agreed.

However, consideration should be given to encouraging traffic authorities to work with relevant partners from the police, health, environment, urban planning, education, and the local community to deliver 20mph limits as part of an integrated approach to addressing transport, community, environment and health objectives. 

The guidance also needs to recognise the concern amongst the public regarding the apparent lack of enforcement, and the general view that the likelihood of being caught exceeding the limit is very small. Where a more proactive enforcement approach by the police is not practical, authorities should be encouraged to consider alternative approaches (e.g. community-based initiatives, use of vehicle activated signs, etc.), which may still require low level involvement of the police.

It is acknowledged that the current guidance is likely to lead to a mix of approaches across the country in terms of speed limits in built up areas, which creates a challenge in terms of embedding a culture of slower speeds in residential and pedestrian environments, and achieving driver compliance where 20mph limits are in place. There may therefore be broader reasons for strengthening the guidance whilst recognising that authorities retain the responsibility for setting speed limits on their roads.

National awareness campaigns – Changing how drivers think about driving in residential locations and areas of high pedestrian and cycle activity is crucial to the success of 20mph limits; and ensuring that compliance with the speed limit becomes the norm. Local authorities have a key role to play here and can engage directly with the local community. However, national publicity (for example, as part of DfT’s Think! road safety speed campaign) could also help highlight the benefits of 20mph limits and reinforce messages about driving at an appropriate speed in residential areas.

Further analysis of safety outcomes – This study has found no significant safety outcome (in terms of collisions and casualties) in residential areas, based on the post implementation data available to date. Due to the small sample sizes and variability in the data, the statistical analysis undertaken to date indicates that the real change could be positive or negative. In addition, it has not been possible to draw any conclusions regarding the relative change in fatal injuries, cycle casualties, and casualties involving older people.

In the case of both the residential and city centre case studies, further data is required to determine the longterm impact of 20mph limits. Collision and casualty rates are known to fluctuate from year to year, and the post implementation data currently available may not be indicative of the longer-term trend.

It is therefore recommended that the safety analysis is updated once five years of data becomes available for each of the case study areas, i.e. once the 2020 STATS19 data has been published. This would be in line with standard evaluation good practice as undertaking a five year post-implementation evaluation is the standard approach for monitoring the impact of major transport schemes.

Further evidence on walking and cycling – This study has found a small (but significant) increase in walking and cycling activity. However, the results are based on self-reported perceptions of behaviour change and may not accurately reflect the real change in the frequency and amount of walking / cycling activity undertaken. In addition, there appears to be a lack of robust evidence from other studies to demonstrate the impact of 20mph limits on walking and cycling levels. Given the central role of walking and cycling in delivering health and environmental benefits, further evidence is needed regarding the strength of
the relationship.

This will be a challenge as change in mode use is influenced by a range of factors and may occur over time rather than as a one-off decision. Long-term analysis of the relationship between walking and cycling activity nationally and the roll out of 20mph limits, may identify a relationship, but would need to take account of external and extraneous factors.

Is 20 plenty for health? Evaluation of the 20mph speed limit networks in Edinburgh and Belfast on a range of public health outcomes.
The NHS National Institute of Health Research has commissioned a major study into the health impacts of 20mph limits based on schemes in Edinburgh and Belfast. The study will run until 2020 and is intended to provide evidence on the impact of 20mph speed limits on safety and levels of physical activity, using surveys and before and after counts. The study is being undertaken by the University of Edinburgh and Sustrans.

Clarity on the role of 20mph limits and air quality – The relationship between speed and air quality is complex and influenced by a mix of factors including vehicle type, brake and tyre wear, variability and consistency of driving speed, traffic volume, and the nature of the road environment. Given the current focus on air quality and the need for action in many local authority areas to meet the requirements of the National Air Quality Plan and EU Air Quality Directive requirements, further clarity on the role that 20mph limit schemes could play would be beneficial.

National database of speed limits – One of the key challenges for this study was the lack of a definitive national database of speed limits identifying the location of all 20mph limits. This would provide the Department for Transport with a greater understanding of the coverage of 20mph limits, and would enable more detailed investigation of national trends and datasets. For example, the rate of collisions and casualties on 20mph limit roads (compared with high limits) at a national level, links between levels of walking and cycling activity (as monitored in the Active People Survey) and the roll out of 20mph limits nationally, the role of 20mph limits in Air Quality Management Areas, etc.

Speedmap is a long-term project with the aim of producing a network-independent national speed limit map for the UK. It has been developed in recognition of the need for an accurate map to support innovation in road safety – without being tied to a costly proprietary mapping solution. 

12.6. Lessons and considerations for local decision-makers

Lessons and considerations for local decision-makers are set out in Section 2.6, covering the following
• clarity around strategic case, objectives and outcomes;
• integration with complementary transport, health, environment and community policies and interventions;
• tailoring the scheme design to local circumstances;
• signage requirements;
• the importance of effective consultation and engagement;
• engagement with young drivers;
• appropriate skillsets;
• management of public expectations;
• revenue cost; and
• monitoring.

Be the first to comment

Please check your e-mail for a link to activate your account.