Editor,— We have recently seen two patients who were injured while walking across raised traffic calming features (sleeping policemen). The first patient, a 56 year old woman could not walk on the pavement as it was blocked by cars. In negotiating the traffic restraint she failed to clear the restraint and caught her foot, stumbling forwards cutting both of her knees. Six months after the injury she has right anterior knee pain caused by the contusional injury. The second, a 60 year old woman, was walking across her road and walked across a parking restraint. She caught her foot and fell forwards onto her outstretched left hand. She sustained an undisplaced distal radial fracture requiring cast treatment.

Sleeping policemen are usually made of the same materials as the road and are usually gently sloping. However, they may be made of different material than the road with different frictional characteristics, they may be sharp, angular and low. It would seem that our patients both misjudged their foot clearance when walking. In both cases the restraints were curved and of the same material as the road, about six inches high. In one case a pavement could not be used. If the restraints are made of a different material to the road surface the friction characteristics may be different and cause difficulties in foot placement and lifting. If they are low and angular they may resemble the ubiquitous raised paving stone. We have heard that these restraints may be inconvenient for emergency traffic including ambulances.

Traffic restraints should be placed in well lit areas of the road, they should have the same frictional or material characteristics of the road, it may be reasonable to place warning notices to take care in crossing these obstructions.

We feel it unlikely that ours are the only injuries caused by this mechanism.