ut speeds in wet fir less rood spray
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.,43 ER SPEED restrictions or c immercial vehicles would 'ed ce wet weather spray 'ro heavy lorries. That's the' on lusion of a report just nib hed by the Department 4 T ansport.
T e Department, in conunc ion with the Transport .nd Road Research as ii atory and the University S•uthampton, carried out a erie of tests at Crowthorne D m asure the effects of difere t mudguard arrangelen P.. and air-flow devices deign:. to reduce spray.
La er equipment was used 3 easure the density of rate particles thrown up by ari us vehicle/trailer/ ont iner combinations as ley sassed over a section of )ad, with a controlled surface 'ate depth, at predetermined )e• increments from 32 km/ (21 mph) to 96 km/h (60 'ph) Th report, No VSE 513, mcl des that fitting a cornna on of mudguards, airevices and drain chart ls no significant Tera 1 improvement to vision, tho gh some minor benefit as oted along the sides of e v hicle.
Ge &ally spray does not co e a problem until ,hicl speeds reach above 64 n/h (40 mph); below 48 km/ (30 mph) spray is scarcely as rable.
Th refore the quick, sure solution would be to restore motorway speeds for large commercial vehicles.
A longer-term solution may lie in the road surface, TRRL has been assessing a previous road surface which allows rainwater to drain directly through the road material, leaving little to be picked up by vehicle tyres.
An evaluation of cost and performance is still under review but the outcome, to be published next year, will have to be balanced against the £28m cost of accidents caused by impaired visibility each year.
The report, Water spray from heavy goods vehicle: an assessment of some vehicle modifications, is available, price £4.70, from the Department of Transport, Room C19/20, 2 Marsham Street, London, SW!.