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Davis cements the connection between transport and health

The connections between transport policy and public health may seem commonsensical but many of the trends are heading in the wrong direction. Academic Adrian Davis is at the centre of efforts to strengthen ties between the transport and health professions. He spoke to Geoff Dudley

Geoff Dudley
23 November 2018
Davis’ essential evidence series is available online at https://travelwest.info/essentialevidence
Davis’ essential evidence series is available online at https://travelwest.info/essentialevidence


For over 30 years Adrian Davis has been at the forefront of the drive to connect and carry forward the disciplines of public health and transport planning. As he observes, for much of this time he has been paving a way into new territory: “In terms of my own journey, there has not been a route map, because the job had previously not been invented.” 

His work has recently taken a new turn with his appointment to the part-time post of professor of transport and health in the Transport Research Institute at Edinburgh Napier University. The university says the appointment is a world-first in this cross-disciplinary field, and Davis sees it as a groundbreaking opportunity to further his work in not only bringing the disciplines together, but also to carry the connections into practical policy-making: “We need to bridge the gap between research and practice. My job is as a boundary spanner, and so to span the disciplinary disconnect. I want to speak to epidemiologists and to transport planners, and to provide training to practitioners in both public health and transport.” He emphasises that, in order to fulfil the cross-disciplinary role, there needs to be greater understanding of the perspectives of transport planners: “What is the rationale of transport planners? Why does the city look the way it does? Why is it so dangerous out on the streets? We need to try to explain the ideological drives, and how progress is defined.”

One of Davis’ principal tasks in bringing public health and transport together is to make the work produced by academics more accessible to decision-makers: “It’s no good academics sitting in ivory towers. There are differences in what planners perceive and what public health specialists take as evidence. There is a challenge between different standards of evidence. This informs my work on translational research. We have people working in local government trying to do their best, but who have no access to the most robust evidence produced by universities. Most of the material is behind paywalls, and in any case many of the papers are written in jargon. This is one of the reasons why, in 2009, I established the ‘Essential Evidence on a Page’ series. In this, I try to de-jargonise academic evidence for practitioners. This can affect decisions, as practitioners have the information to hand in a usable form. I am still staggered there is so little translational material on transport and the environment.”

In terms of working with practitioners, for the past decade Davis has occupied another unique role. “In 2008, the director of public health asked me to come and work within Bristol City Council, and so I became the only public health specialist in transport and health embedded in a municipal authority. I’m still there a day a week. It means I am able to drop evidence into a committee report for elected members to make a decision. This creates a direct line from academic work into the democratic process. For example, I provided the methodological structure for how to design 20mph speed limits in Bristol.” 

Traffic calming

His work on the interconnections between public health and transport had its initial impetus in the 1980s: “In the mid-1980s there was very little focus on looking at the impacts of transport systems on public health. I became very interested in the World Health Organisation’s ‘Healthy Cities Movement’. At that time, different people in the same city could be working towards the same outcomes, but would not know each other existed, because one would be working in transport planning, and the other in health policy. There were enormous silos separating the two of them. One of the early findings of the Healthy Cities Movement was the codified language between professions. This can cause problems, such as unintended consequences. For example, if we accentuate the number of people killed or injured while cycling and walking then this can deter the population from doing these. We therefore need to think of the city as a system, and what are the effects over the whole of it.”

One of his notable early successes was as a pioneer of traffic calming: “I was working on a Town and Country Planning Association project in Manchester in the 1980s, trying to promote ways to slow down motor vehicles. It seemed like a heretic’s job at that time. There were only two sets of road humps in the UK, one in Manchester, the other in London. The rules and regulations were so tight it was hard to get them implemented, and I went on trips to see the road humps. While in Manchester, we were struggling with engineers who didn’t want to do anything to slow down motor vehicles, but in 1988 the Transport and Health Study Group was formed. This is now in its 30th year, and has run along in the background with virtually no funding, thanks as much as anything to the persistence of Dr Steve Watkins, who has recently retired as director of public health in Stockport, and was the long time chair of the study group. Joining the study group allowed me to formulate ideas about transport and health in a broader way.”

Davis was able to use this knowledge in the late-1980s when he moved to London to work for Friends of the Earth in their transport team as a researcher: “My principal job description was to bring traffic calming to the UK. As it happened, the Conservative MP Keith Manns had a long interest in environmental matters, and although this was the high water mark of Thatcherism in terms of promoting the virtues of road-building, he wanted to do something to slow down motor vehicles.

“Fortunately, he came out fourth in the ballot for Private Members’ Bills, and so brought forward a Bill to clarify the law on traffic calming. In 1989 the Department of Transport produced a leaflet on traffic calming, and so we were able to work with civil servants on framing the Bill. This became the 1992 Traffic Calming Act, which clarified the law so that local authorities would not be sued by introducing horizontal and vertical deflections on the carriageway. This was therefore quite a quirky thing of an environmental group joining up with a Tory MP to pass a Bill to improve road safety.”

Having seen this work through, Davis decided to move into the academic world: “Environmental groups such as Friends of the Earth rely on your enthusiasm for the work, but pay badly, and this can squeeze you dry. By 1994 I had had enough, and so moved to the Open University as a research fellow. While there, I worked on the hypothesis, put forward by Mayer Hillman, on children’s independent mobility declining as a result of a car culture. This could be contrasted with public health messages for young people to be out and about, when in reality they were constrained by the hostile road transport system. While at the Open University Davis completed a PhD on inter-sectoral collaboration on transport and health. 

Napier and UWE

Davis then spent five years at the University of Westminster, and in 2012 was made a visiting professor in transport and health at the University of the West of England in Bristol. This post developed in 2017 when he began working a day a week within UWE’s business school. “In the business school I worked closely with social marketers, particularly Professor Alan Tapp. We have done a lot of work around 20mph speed limits, including surveys for YouGov on public attitudes to the limits. One of the things social marketers can help with is on how we change social norms around behaviours.”

As well as now working at Napier, Davis is continuing his work at UWE, and spends a week in Bristol and a week in Edinburgh. He sees one of his principal roles at Napier as being to draw together disparate communities across Scotland: “How do we address transport and health in its broad range of aspects? For example, across the whole issue of air quality, we need to know more about the impacts of road transport on foetal health, and also declining cognition in older life as a result of air pollution. These types of subjects may become much larger across the landscape of transport and health.

“There is also research on inactivity across populations. The last 15 years have seen trends towards increasing inactivity, leading to cardio-vascular disease, the number one cause of premature death. There has been a massive decline in activity across the population as a result of mechanisation, such as the growth of sedentary transport. Research has taken off in these areas, and I have worked with the World Health Organisation’s Regional Office for Europe. We can see that there is a direct link between transport mode choice and weight gain. More robust research can establish the causal relationships between road transport and public health, and this can encourage governments to look at the outcomes of road transport. 

“In this respect we need to get clinicians to stand up and do more than they do. For example, when I started working on patterns of activity, we talked about moderate or vigorous activity, or just activity itself. Science has now moved on and created a fourth category of sedentariness. Thus some people do so little physical activity in a week that we have to categorise them as sedentary. Twenty-five per cent of the adult population do less than 30 minutes physical activity per week, which is quite shocking.

“In order to deal with these problems, we need to examine both science and intervention effects. What are the interventions that can ameliorate problems? In structural terms, how do we need to operate across professions, in order to get out of silo thinking? This is a difficult and long-term challenge, and will be one of the things I will be trying to do at Napier. Consequently, how do we move to a more public health-led approach?” In this respect, another recent initiative by Davis is that he has worked with the Urban Transport Group to develop a health and wellbeing hub on the UTG website (LTT 31 Aug).  

Whole population research

Davis argues that transport planning can make significant gains from adopting research methods from public health: “In public health the standard method is to look at whole populations. Instead, in transport planning we tend to look at small individual groups. For example, in terms of road safety, we might find that 17-25 year old male drivers are good at killing themselves and others at 2am on a Saturday morning. They are a high-risk group, but overall the most benefits would result from an intervention that touched everybody, and adds up to a bigger change across society. Thus if a 20mph limit is introduced, then everyone in the area will be aware of the limit. If we just get a few miles per hour reduction, then this reduces the overall risk. This is called a population level strategy. The other part of this is the prevention paradox. This entails asking so little of people that they are hardly aware of it. A minority of people will shout loud in protest, but for most people it will have little effect. Having introduced these measures, we can then look at what we can do for high risk groups.”

Overall, Davis believes that transport research methods could be significantly improved: “Historically, transport research has suffered from weaknesses in study design. We tend not to get meta analysis, such as longitudinal cohort studies, that are more common in public health, such as following Mrs Jones across her life, which helps to trace the origins and spread of diseases. This would be good to apply to travel behaviour changes such as mode choice over time. In this context, at Napier I want to work with people in health sciences and other faculties, and not be bound by framing within disciplines. This narrower view can prevent you from seeing the big landscape.”

Davis believes there is an urgent need to look at total systems in transport planning: “If you look at towns and cities, more people want to walk and cycle. There is a suppressed demand here, but there is still a long way to go. We need to do more to create safe systems to improve road safety. Thus people may look outside the door to see if it is safe to be able to walk or cycle for such things as school trips. The answer can be ‘yes’ if we have got 20mph speed limits and other measures. In fact, the culture for walking and cycling is often more common in affluent areas, which is a problem that needs to be addressed.”

The 20mph debate

Davis says 20mph speed limits in built-up areas form a central plank of safe systems, but their effectiveness has come under increasing scrutiny. In Scotland, Green Party MSP Mark Ruskell has introduced a Bill to Parliament that would make 20mph the default speed limit on most roads in built-up areas. In preparing the Bill, Ruskell commissioned work from Alan Tapp and Davis of UWE that recommended a three-stranded approach to achieving compliance: targeted enforcement; a population level social marketing culture change campaign; and community-level engagement activities (LTT 28 Sep). Davis has also prepared an evidence review of 20mph limits for the Welsh Government, which is considering how to use recently devolved powers to set speed limits. First Minister Carwyn Jones has stated that the Davis review will inform any future policy development (LTT 20 Jul).

The Scottish Bill has its critics, amongst them the Parliamentary Advisory Council for Transport Safety (PACTS), which has urged the Greens and the Scottish Government to look closely at the research evidence, such as exists, and not to rely on “wishful thinking and unsubstantiated claims”. It said signed-only 20mph delivered reductions of less than 1mph in average speeds, and there was no evidence they increased levels of active travel or improved air quality. PACTS added that their failure to bring down driver speeds to below the limit undermined the credibility of speed limits (LTT 14 Sep).

Responding to these criticisms, Davis argues that there is evidence in support of 20mph limits: “A 2001 study in Scotland examined 78 locations [of advisory 20mph speed limits], which showed that [the] speed limits reduced casualties, and were liked in communities. In public health and transport terms, we need to think about kinetic energy and the systems approach. Thus small reductions can have an effect. For example, in a 30mph area, someone may be used to driving at 36mph, but if the limit is 20mph, then they may reduce their speed to 28mph. That means an 8mph difference, but if you are hit by someone doing around 36mph, then you are very likely to die, whereas at 28mph there is a good chance of you surviving. At a speed of 20mph, then your chances of survival are considerably better.”

He says there can be considerable latent public support for measures such as 20mph limits. This is termed the pluralistic paradox, and is the subject of one of his Essential Evidence on a Page series: “In surveys, you find that around 73 per cant of adults support 20mph limits, and where these are implemented support goes up about 10 per cent. So the majority support it, but paradoxically believe that they are in the minority. This has the effect of creating spirals of silence. People think that they shouldn’t talk about it because they are in the minority. It needs politicians to understand this pluralistic paradox, particularly when you get shouty people, such as middle aged male drivers, who protest about 20mph limits. These are real political challenges.”

Government and leadership

Davis believes that, in order to change public behaviours, more is required of governments: “Governments have a major role to play in bringing about change. Human behaviour will move slowly, but can be speeded up much more rapidly with government action. I think the importance of the government is illustrated through programmes in recent years such as Sustainable Travel Towns, Cycling Demonstration Towns, and the Local Sustainable Transport Fund. They indicate the benefits of whole town or city programmes. It is no good just doing small corridor stuff. Things need to happen much faster, across the whole city. We need to think about land-use, so that where we do a number of interventions at the same time, we will get more than the sum of the parts.”

Davis says leadership is required, and cites the example of Chris Boardman, the cycling and walking commissioner for Greater Manchester, as someone with the approach needed. He also believes there is greater scope for cross-party agreement: “It would be nice if these things could be achieved with a wider cross-party consensus. For example, when it came to office in 2010 the coalition Government abolished several cycling quangos, but these had produced benefits for the whole community. It’s much better if we can work together as a society. The elephant in the room underlying all this is climate change, and if there is not something done in the next few years to deal with this, then we are stuffed.”

Davis acknowledges that technological developments, such as electric bicycles and Mobility as a Service, can promote change, but says shifting human behaviour is the key: “Technology has to prove itself. There is a lot of hype around it, but it may not necessarily follow through. In the case of such things as climate change, it is about how human beings change behaviour, and there is an enormous challenge in persuading people to move to low carbon lifestyles. So often governments adopt short-term horizons. The key is to convince people that behaviour change doesn’t mean a loss in the quality of life.” 

Adrian will be speaking at the 3rd annual Public Health & Sustainable Transport Summit, 27th March, City Hall, Bristol - www.transportandhealth.co.uk 

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