There has been a mixed reaction to the announcement by Transport Secretary Alistair Darling that a mile-long stretch of the M62 andM606 motorways is to be designated as Britain's first multi-occupancy lane in bid to speed up rush-hour traffic on this busy commuter route.

The policy is designed to encourage people to car share rather than use two or more vehicles for the same journey. It is a very good idea where it is practicable - when, for instance, people who live close to each other also work together or nearby and start and finish around the same time.

But it does discriminate against those who work unusual hours or have jobs which mean they can only drive as a single occupant: reps, for instance, or delivery van and lorry drivers, who will find themselves forced into crowded single-occupancy lanes while at many times of the day the car-share lane is under-used.

The policy is also somewhat at odds with the Government encouraging people to work more flexible hours, which reduces the opportunities for finding compatible travelling companions.

A bigger concern, though, is the suggestion that the hard shoulder could be used for some parts of this lane. That surely is potentially disastrous on this busy stretch of road, where broken-down vehicles need to be able to pull to the side.

Similar schemes as this have had mixed success elsewhere in the world, particularly in the United States where some are reported to have been withdrawn. However, the proof of the pudding will no doubt become clear fairly quickly after the scheme is introduced next year.