This Easter, motorists will experience the familiar frustration of being stuck on a motorway in a stop-start traffic jam that eventually disperses with no apparent cause. Researchers have found that although most changes in vehicle speed and road position get absorbed by traffic flow, they sometimes combine in a 'perfect storm' to create 'phantom' traffic jams. Understanding why this happens is being studied in a project supported by the Engineering and Physical Sciences Research Council (EPSRC) that will lead to better traffic flow forecasting to help prevent congestion. The project, led by Dr Eddie Wilson from the University of Bristol, has made progress in creating mathematical models for describing phantom traffic jams, or stop-and-go waves in motorway traffic.
Dr Wilson will talk about his research on the BBC One Show on Friday 2 April (planned broadcast date).
The traffic models have been looked at in a new way using 'string instability' theory to test how good existing computer-based methods are at predicting how traffic flows and queues build up and dissipate.
Dr Wilson says: "The stop-and-go waves are generated by very small events at the level of individual vehicles. There's something about traffic that magnifies small effects to create large changes in certain situations."
He has identified patterns in existing traffic models that will make working on more complicated scenarios possible, and could lead to more accurate forecasting of traffic flow.
The next stage of the project will see the best of these traffic models being combined in a way that allows them to learn from experience and observation. This will give a human-like artificial intelligence to these computer-based ways of forecasting traffic.
The project uses data taken from a particularly busy 10-mile stretch of the M42 near Birmingham that has one of the highest concentrations of traffic monitoring equipment in the world. This means individual vehicles can be tracked through a specially-instrumented one-mile section of this stretch in most traffic conditions to reconstruct their travel paths.
The work is being carried out in collaboration with project partners the Highways Agency, Knowledge Transfer Network for Industrial Mathematics, and TRL.
Notes for Editors
The short film 'Motorway Madness' (BBC Britain From Above) illustrates how phantom traffic jams are formed.
Traffic – fast facts
- The average road user spends six months of their life in traffic jams
- Road congestion costs the UK economy roughly £7-8 billion a year
- UK road traffic has grown by a quarter in just 20 years
- UK road traffic was forecast to grow by 30% between 2000 and 2015
- According to the CBI employers' group, the cost of road congestion to the economy is likely to more than double by 2025 unless changes are made to working habits, such as staggering commute times.
Sources: CBI & BBC
Dr Eddie Wilson's work focuses on microscopic linear stability modelling. String instability, when applied to linear stability modelling, shows how an envelope of traffic movement (fluctuations) grows as it travels up a column of traffic, but each individual vehicle returns to equilibrium after the envelope has passed.
The research considers a single lane of traffic in a car-following model, with identical vehicles going in the same direction, and looks at position, speed and distance between the vehicles.
Engineering and Physical Sciences Research Council (EPSRC)
EPSRC is the main UK government agency for funding research and training in engineering and the physical sciences, investing more than £850 million a year in a broad range of subjects – from mathematics to materials science, and from information technology to structural engineering. www.epsrc.ac.uk.
University of Bristol
The University of Bristol is consistently ranked among the leaders in UK higher education. According to The Times Higher Education World University Rankings 2009, it is among the top 35 universities in the world. Research-intensive and with an international reputation for quality and innovation, the University has 17,000 students from over 100 countries, together with more than 5,500 staff. In terms of the number of applications per undergraduate place, Bristol is arguably the most popular university in the country.
For further information, interview requests and images contact:
Wednesday 31 March
EPSRC Press Office
Tel: 01793 444404 or email: pressoffice@epsrc.ac.uk
Thursday 1 April
Cherry Lewis, University of Bristol Press Office
Tel: 0117 928 7777
For interviews and technical questions:
Dr Eddie Wilson
Tel: 0117 331 5627 or email: re.wilson@bristol.ac.uk
Image details
Image: Traffic signs (High resolution photo, 1Mb)
Suggested caption: Managed motorways in action on the M42 (Credit: Highways Agency)
Image: Stop and go waves (Technical image - graphs)
Caption: A busy Friday afternoon on the north-bound M42 motorway. The colour denotes the speed of traffic as measured by the Highways Agency MIDAS detector system (blue is fast, red is slow), and the plots show how congestion evolves jointly in space and time. The right hand picture shows the detailed structure of an individual stop-and-go wave which 'rolls back' against the flow of the traffic at about 18km/h. This wave is generated by instability in the neighbourhood of Junction 6.