Written question asked by Lord Mann (Labour) on Wednesday, 18 May 2005, in the House of Commons. It was due for an answer on Monday, 23 May 2005. It was answered by Stephen Ladyman (Labour) on Monday, 23 May 2005 on behalf of the Department for Transport.

Road Humps

Question: To ask the Secretary of State for Transport when the merits of the design of the cushion road hump last underwent scientific testing; and what the conclusions of those tests were.

Answer: A speed cushion was one of the hump types tested in recent research into the impact of road humps on vehicles and their occupants. The results, published in 2004, found:"no evidence of vehicle damage from repeated traverses, although some small changes in steering geometry were noted;""peak vertical accelerations (which strongly correlate to discomfort ratings) for all vehicles (including an ambulance, bus and minibus) were lower when traversing cushions than when traversing other types of hump;""no evidence that alternative hump dimensions to those currently recommended could remove any unnecessary discomfort and maintain safety objectives;""predicted spinal ligament forces were almost an order of magnitude smaller than the damage threshold for such ligaments and predicted forces transmitted through the spine were at least a factor of four smaller than those generated in discs by heavy lifting. Therefore, although it is not possible to predict the effect of such forces on people with pre-existing spinal conditions, it was considered that vehicle occupants with healthy spines were very unlikely to be injured as a result of single or repeated traversing of road humps (including cushions) constructed to recommended dimensions."

Secondary information