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Viewpoint - Douglas Reid

Road planners could learn a lot from the success of safety schemes.

The Eddington report of late 2006 highlighted the importance of measuring and ranking transport problems as the precursor to seeking solutions. Before jumping to any particular proposal, the idea is that we quantify the problem in the same way that we would measure the success of any actual scheme outcome.

In most areas of activity, this way of looking at things would be second nature, but on UK roads we do things very differently.

Instead of a logical approach to problem solving, we see considerable expenditure on road alterations for which there are few indicators of success, nor evidence of a transport problem solved.

What often seems missing is a understanding of cause and effect, agreed and quantifiable transport objectives, follow-up efforts to discover what works best on the ground, and how the measured outcomes might have been achieved at less cost.

An exception is accident investigation and prevention (AIP), which for more than 30 years has stuck doggedly to problem solving
engineering principles, and achieved world leading success.

Road accident problems have been measured and quantified, schemes devised and prioritised, and outcomes quantified following construction, as needed for statistical confidence. By doing this, UK roads have competed with Swedish roads to be safest in the world.

However, the current slow down in UK accident reduction is worrying, particularly where visible policing has been withdrawn at the times of day when serious road accidents are known to occur.

The real challenge now is to apply those problem solving principles to roads and transport more generally, use the best technology to quantify transport problems, and measure how well or badly we might be doing.

Congestion is probably the greatest area of opportunity for approaching things in this new way. While UK traffic signals and systems are world class and heavily exported, no current system seems able measure its own congestion performance as experienced on street.

Without such quantified feedback, it's difficult to see how we can start a problem solving process. While we map other transport problems, including accessibility, accidents and air quality, congestion mapping down to junction level is not yet done.

From GPS vehicle tracking data, there is continuous measurement of speeds over short road lengths throughout the UK. By aggregating such data over a year, it ought to be possible to map congestion for a typical busy weekday. The mapping of speeds, perhaps over 100m road lengths, would flag up endemic queuing at junctions on both main roads and side roads.

Like accident mapping, this would become the springboard for investigating bad junction performance, the cause of most routine congestion.

There would then be an obvious basis for trying to do things to lessen the congestion problem, and be held to account for year on year congestion performance. There would be a measurable disincentive for road schemes which knowingly make congestion worse.

- Dr Douglas Reid is a director of JCT Consultancy

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