Local highway authorities would be advised to reduce forward visibility for drivers from the current standards, after modelling for the Manual for streets project suggested this would reduce average speeds.
But while the draft of the replacement for Design bulletin 32 recommended reducing stopping-sight distances to as little as 22m, it urged ‘caution,’ because vehicles travelling at well above-average speeds would stop with just metres to spare should a pedestrian unexpectedly appear.
Basing stopping-sight distances on the assumption that the reaction times of British drivers were twice that of the Dutch has been criticised for adding ‘thousands of extra acres of carriageway space’ (Surveyor, 16 June 2005). ~Living Streets~ believes that maximising driver forward visibility – by keeping roads wide and buildings far back from the road line at junctions – makes conditions worse for pedestrians. Modelling for the Manual for streets project on roads where average speeds of 10-24mph were recorded indicated that reducing visibility reduced speeds, but the reduction ‘does not fully compensate for the reduction in visibility’.
The potential danger was that those driving at 1/85 quartile speeds – up to 8mph faster than the average – would be left with little margin for error. Despite this, the draft proposes revising down stopping-sight distances from 70m to 40m on 30mph roads, and from 33m to 22m on 20mph roads, pointing to international practice and research showing that 85% of drivers react in less than 1.4 seconds. The draft also advises that there should be ‘no hard and fast rules’ on road widths, paving the way for narrower carriageways, and recommends ‘a presumption in favour of straight streets because pedestrians like to walk in straight lines’.
Edward Chorlton, ~Devon County Council~'s environment director and member of the project’s sounding board, backed the approach taken by the team of consultants, led by WSP Group. ‘Roads can never be laid out so they’re safe for everybody, no matter how they’re behaving – we can’t have a risk-free society.’ The current standards had created car-dominated environments and a re-balancing was needed.
Richard Hebditch, policy officer at ~Living Streets~ agreed there was only so much that could be achieved with the layout of roads. ‘The draft manual should lead to more pedestrian-friendly streets. ‘But it needs to be part of a wider strategy – even with more restricted visiblity, we will still get people driving like idiots. Why should we design our roads to cater for them?’ Proactive enforcement would still be required.
John Smart, director of technical affairs at the ~Institution of Highways and Transportation~ also welcomed the proposals, having championed revisiting the standards in his previous job at the ~Highways Agency~ ‘Modern cars can brake and accelerate much more quickly than they could when the standards were drawn up. If drivers can see far ahead and have a wide, open, road, they’ll go faster than they should over relatively small distances,’ he said. : www.manualforstreets.org.uk
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