THE stealth bollard has been active for a matter of days and already it has injured two drivers and damaged two cars. Not bad for a road safety measure.

City of York Council highway chiefs say the bollard, which rises from Stonebow to block unauthorised traffic, is "operating properly". Unless the device was installed with the intention of hospitalising errant motorists, that claim must be questionable.

Speed humps and falling barriers work because they are visible. A "now you see it, now you don't" bollard is bound to cause accidents. Motorists who miss or ignore the warning signs may be guilty of a transgression, but that does not mean they deserve a bump on the head and a large garage bill.

Now a flashing warning sign is to be installed to alert drivers to the device. If this does not stop the accidents, the bollard must be switched off, never to rise again. A more immediately visible traffic deterrent - such as a barrier - may be more useful, and safer.