Tag Archives: Rat Running

Induced Traffic and Traffic Evaporation

The recent debate on the proposed Callington “Relief” Road has brought the concept of “induced traffic” back into the limelight. And also the the related and much neglected evidence for “reduced traffic“, or the delightful concept of “traffic evaporation”. So what do these terms mean?

Induced Traffic

As car ownership and use have increased over the past 30 years the reaction to the pressure created by additional traffic demand has often been to increase the level of supply, in other words, provide additional road space. There is a growing body of evidence indicating that the benefits of creating additional road capacity are not as significant as was previously believed. In many cases, the provision of new road links simply increases congestion problems. This occurs through a process that is known as traffic ‘induction’. In 1994, the UK Government-commissioned Sactra report provided evidence on the impact of new road building on traffic levels in the area of the scheme. The report revealed that when new road capacity is provided, overall traffic levels in the vicinity of the scheme actually increase. The evidence does not offer a reliable means of predicting the extent of this traffic increase but case studies suggest that it is typically around 10 % in the short term, and 20 % in the longer term. In our cities, such as Bristol, there is an additional reason as to why the provision of additional road capacity is problematic for city planners — there is simply a lack of available space in which to expand.

Two recent reports from the Campaign to Protect Rural England on “the Impact of Road Projects in England” and “The End of the Road, Challenging the Road Building Consensus” discuss the latest evidence on the failure of road building projects to do anything more than attract more cars, increasing noise, air pollution and accidents. There is also is sound research evidence to back the benefits and impacts of pedestrian improvements and road closures as set out in the new website from the UWE Centre for Transport and Society.

Traffic Evaporation

So if building or widening roads causes more traffic, what happens when capacity is restricted or redirected? Chaos, surely? Well the evidence points to something else, something that unexpected, a phenomenon that has been called traffic evaporation, disappearing traffic, traffic suppression, or, more generally, reduced demand. The fact is that some traffic is displaced to other modes, and some simply vanishes, with no seeming inconvenience or disruption.

Case Study – Wolverhampton Town Centre

This case study examines a response to intense traffic congestion, worsening environmental conditions and declining economic activity in Wolverhampton in the face of competition from other shopping centres in the city of Telford to the west, and the Merry Hill complex to the south-east, and additional planned retail centres. In 1986, the local authority commissioned ‘The Black Country Integrated Transport study’ which concluded that building more roads would not solve the growing transport problems.

A more effective strategy would be to give greater priority to public transport and to put greater emphasis on improving the urban environment by creating an attractive physical space that would meet the public’s expectations. The response was a four-stage strategy, central to which was the removal of approximately 8 000 through-traffic cars per day from the city centre. The predicted traffic congestion did not occur. A significant percentage of traffic appears to have disappeared from the city centre, a result which could not be solely explained by displacement to other routes.

Below we’ve put together a short storyboard showing how the theories of induced traffic and traffic evaporation play out in reality.

The concept of “Induced Traffic” and “Traffic Evaporation”

Download our handout from the Callington Road meeting: 

Induced traffic and evaporation



Easton Safer Streets – ask councillors to support

Update:  The proposal has been scaled back to just a single street. Everyone loses.

There is a key decision point on Friday 10th Nov for Easton Safer Streets. Please show your support using the button below. This is Bristol’s first attempt to make a big difference to the vitality of an area by a joined up approach to through traffic (rat-running), rather than a piecemeal street by street approach. Of all the projects in the Cycling Ambition Fund package this is the one with the greatest potential to benefit whole communities, and offers a model for other areas. It continued after local councillors backed down on rat run measures in Windmill Hill Deterring through traffic in Windmill Hill.

There has been a very extensive and detailed ‘co-design’ process involving hundreds of people and dozens of events and meetings, lead by Sustrans. The final design proposals are being considered on Friday 10 November 2017 by the six councillors of the Easton, Eastville and Lawrence Hill wards to decide whether to move on the next stage of formal consultation.

As with all such proposals there is a vigorous lobby against change. We are encouraging everyone who lives in the area, or is affected by the changes, or who would like safer streets in their area, to contact the key six councillors to show their support. We’ve made it easy for you with this button which will open an email with all the info ready for you to add any comments.

Email the Councillors [add your name and comment]

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Joint Spatial Plan and Transport Study Consultation – have your say

Update  West of England Joint Transport Study Consultation Nov 2016 – our response

Will Greater Bristol ever become a true Cycling City? The Joint Spatial Plan sets out how to build 85,000 new houses and the modern transport links for a growing region over the next 20 years. It’s out for consultation until 19th December but even Bristol Mayor Marvin Rees is calling for more ambition.

Overall we feel not much has changed since our initial response in January Joint Spatial Plan and Joint Transport Study – our response. We encourage everyone to respond to the sensible questions in the consultation and to read the Transport Vision Summary Document. Some points we picked up:

  • current mode share of cars is 55% but needs to fall to 43% just to keep congestion at current level.
  • The study makes use of an  iconic image that says it all really.
  • Distance is critical for walking & cycling. Quality is next. Unless the Spatial Plan reduces the need for longer commutes it will be impossible for large numbers to make healthy & sustainable transport choices.
  • Total investment of £7.5 billion Transport Vision for delivery over the next twenty years, £0.4 billion for walking/cycling.
  • Proposal for ‘more strategic  cycling and walking corridors with better infrastructure’ is welcome but only by taking a whole carriageway corridor approach will change be possible.
  • There is a promising statement that ‘diversion of through traffic movements frees up highway space for sustainable transport modes’
  • Overall it appears that there is a projected increase in active travel modes by only 6% over the whole period. We consider this to be hopelessly inadequate to the scale of the health challenge we face.

There is a consultation video and some Frequently Asked Questions which provide more information and an overview of the issues. These are the main questions in the consultation:

  • The level of ambition in the Transport Vision, is it about right, too ambitious or not ambitious enough?
  • Whether the balance between different transport modes is right? Is there too much emphasis on public transport and cycling, or not enough?
  • How best to manage traffic? How radical should we be in our treatment of `through’ traffic?
  • What our options are to raise funds to deliver the Transport Vision?
  • What infrastructure should be provided to support the emerging development locations: schools, libraries, utilities (including broadband) and transport?

There’s a lot of good information on current levels of cycling in the 2015 report Bike Life – Taking the pulse of bike life in Bristol.

At the same time you should also respond to the Bristol Council Corporate Strategy consultation 2017-2022 – good for cycling?.

This graph shows the travel modes that a sensible transport policy would enable people to choose. At present our view is that it’s the hostility of the cycling environment that means this mode above all others is vastly underused.



There is a transport and infrastructure workshop on Wednesday 7 December 10.30am-12.30pm at MShed, Princes Wharf, Wapping Rd, Bristol BS1 4RN. You will need to register your free place.


There will be further discussion on the Bristol Cycling Campaign response to this consultation at the December meeting of our Infrastructure Forum on Thursday 8th Dec, see our  Diary page.

Bristol Council Corporate Strategy consultation 2017-2022 – good for cycling?

Bristol Council has published the Corporate Strategy consultation 2017-2022. There are immensely hard choices to be made. Traditionally this means that those at the bottom of the pile are hit hardest. In transport terms, this means those who choose the cheapest and healthiest options of walking and cycling.

What does the strategy have say about cycling?

[bs_notification type=”danger” dismissible=”false”]Headline Action: Use the consultation to ask that walking and cycling be considered as strategic priorities rather than afterthoughts.[/bs_notification]

Mayor Marvin Rees places equality and health at the centre of his plans, and aims to “improve our transport to connect people to opportunity and tackle congestion”. In his ‘open letter to Bristol‘ he says:

We need to develop an understanding of where we want the city to be in four years and beyond and ensure we have the council operating in a way that will get us there. […] We have to reinvent the role of Bristol City Council in light of the available finances. It must maintain its leadership role and must continue to fight for good outcomes for people from the city. But we will have to work in new ways. This includes taking a strategic approach to identify what can be done better and more cost effectively.

There is a strong statement on buses and public transport. Much of this could apply to cycling and walking – try swapping those terms in the following paragraph:

In seeking to tackle congestion, the council needs to work with others to promote public transport use by creating better priority for buses on the road network, by improving the attractiveness of bus travel, especially through integrated ticketing, and by delivering major public transport improvement programmes such as MetroBus and MetroWest rail. The particular geography of the city, with its hills, river crossings and rail lines, as well as its historic road layout, present unique challenges in seeking to improve cross-city connectivity. Money to invest in transport infrastructure is hard to come by and serious thought needs to be given to new ways of generating funding for the future, we have set up a Congestion Task Group and all options will be explored.

Instead, we get this limp and frankly outrageous statement based on the false premise that it is hills rather than road danger that deters people from cycling:

Encouraging more walking and cycling in a hilly city continues to be a challenge, as indeed does increasing participation in order to promote healthy lifestyles, but we need to build on previous years’ success in securing Government money to invest more in cycle tracks, safe routes and crossings.

It is clear that there is no intention to challenge the status quo or find new ways of working. Any change will continue to be expensively and ineffectually bolted on the side based on whatever small pots of funding can be secured.

Other points relating to cycling are:

  • To have delivered on our promise to review residents’ parking schemes and 20mph speed limits with local councillors and be able to respond to community priorities for highway improvements.
    Delivering a review? Is this progress?
  • To produce a comprehensive Bristol Transport Plan with a particular focus on the steps required to deliver against the key objective of tackling congestion.
    This could be very useful in setting strategic objectives, if the political will is there. See for example what London has achieved.
  • Develop an air quality action plan. Through the Mayoral Combined Authority, pursue powers to introduce low emission or clean air zones.
    Another promising objective that could be used to great effect.
  • Remove the funding for local traffic schemes currently devolved to Neighbourhood Partnerships (RS3) –
    Currently Neighbourhood Partnerships are given £350k to provide smaller local traffic schemes, which could be removed generating (including staff costs) a £410k saving. Note that delivery of current planned schemes may be impacted.
    A mixed blessing. Much of the focus of this pot was used for ‘tinkering’ schemes that fiddled at the margins of the main issues. Lots of crossings for example, without considering options for reducing traffic and rat-running. Nevertheless, local schemes can have significant effects.
  • Agree a West of England Joint Spatial Plan and Joint Transport Plan that prioritises investment in the urban area.
    Another promising objective that could be used to great effect. There will also be an Economic Plan for the city centre, and revisions to the Bristol Local Plan that could in theory offer and forward thinking and evidence lead approach to planning for a city ‘where cycling and walking are so easy that everyone does it’ (that’s from the BCyC vision statement in case you don’t recognise it).

Deterring through traffic in Windmill Hill

Ref: https://bristol.citizenspace.com/business-change/traffic-in-windmill-hill

Our overall position on this consultation is: Support
A well thought out and potentially transformational example of creating ‘Streets for All’ that should be followed in many other neighbourhoods.

Space for Cycling Does this measure provide for 1) Protected space on main roads; 2) Remove through motor traffic; 3) Safe routes to school; 4) Cycle friendly town centres; 5) Cycle routes in green spaces; 6) 20mph speed limits? Green – overall benefit
Road Danger Reduction Does this measure seek a genuine reduction in danger for all road users by identifying and controlling the principal sources of threat? Green – overall benefit
Triple A Quality(All Ages and Abilities) Will this measure be attractive to all ages and abilities using all kinds of cycles? Green – overall benefit
Strategic Cycling Network How does this measure contribute to the development of Bristol Council’s planned integrated and coherent strategic cycle network? Amber – overall neutral
Cycle-proofing How far does this measure provide for Triple A Space for Cycling in the future? Green – overall benefit

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