Birmingham's first high-occupancy vehicle lane, where motorists will be fined if they fail to carry a passenger, is likely to prove impossible to police, it was claimed last night.

City transport chiefs admitted that infra-red camera technology to check on the four-mile route along the Heartlands Spine Road is still being developed and is unlikely to be available when the experiment begins.

Police patrols will be responsible for checking on drivers, who must carry at least one passenger in order to use the priority lane.

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But the Spine Road has no lay-bys for the patrols to wait in, raising questions about the difficulties police officers will face in checking vehicles.

The council cabinet yesterday agreed to press ahead with a £50,000 study into a high-occupancy lane, despite claims by Labour councillors that the wrong road had been chosen.

They said that, since there were few incidents of congestion along the Spine Road, it was impossible to judge the effectiveness of a high-occupancy vehicle lane.

Kath Hartley, Labour transportation spokeswoman, said arterial roads carrying a larger amount of rush hour traffic would have been more appropriate, including Bristol Road, Coventry Road, Hagley Road and the Aston Expressway.

Coun Hartley ( Ladywood) said a similar scheme in Leeds had problems because of problems with camera detection. West Yorkshire Police was forced to allow motorists two chances before prosecuting.

Coun Peter Kane (Lab Kingstanding) believed the council had missed an opportunity by not combining high-occupancy vehicle lanes with bus lanes.

Labour's fears were dismissed by Len Gregory, cabinet member for transportation, who said the Spine Road experiment would prove to be an innovative way of tackling traffic congestion.