The coach that relied on sat-nav

For a coachload of pensioners from Bristol, it was supposed to have been a pleasant day trip for a pub lunch. It turned out to be a punishing lesson in the folly of unquestioning belief in technology.

Rather than speeding seamlessly to the scenery of the Forest of Dean, the coach found itself wedged between hedgerows for nearly four hours after the driver's satellite-navigation gadget sent her vehicle down an impassable country lane .

The dramafor the day-trippers in the Gloucestershire hamlet of Stroat was only ended with the help of some decidedly less-advanced machinery.

A farmer with a tractor pulled the stranded coach free, allowing it to finally struggle back to the main road by trundling across three fields of stubble.

The satellite-guided mishap is the latest in a series of incidents where drivers slavishly following their "sat-nav" have found themselves directed into fords, muddy tracks and, in one case, to the edge of a 100ft drop.

Demand for hi-tech boxes which guide vehicles to their destinations has rocketed in the past18 months, creating a £300m industry. The marketing consultancy Canalys revealed this week that 405,000 of the navigation aids were sold between April and June - more than double the figure in 2005. Some 1.8 million sat-navs have been sold since January 2005.

But the infallibility of the latest must-have gizmo provided little solace for the 50 pensioners on board the coach, belonging to the Bristol-based firm Buglers, after it missed a turning en route to a country pub on the edge of the Forest of Dean.

At least five residents on Rosemary Lane in Stroat, close to Chepstow, waved helplessly as the vehicle turned off the busy A48 road to Gloucester to try to cut across country to its destination in the village of Sling.

About a mile down the winding single-track road - marked with a sign saying Unsuitable for HGVs - the eight-metre coach became trapped on a tight bend. While a method to extract the vehicle was devised, the day-trippers were offered cups of tea and the use of the lavatory in an adjoining house.

By the time the coach had been freed at 3.30pm, it was too late for the planned lunch. Instead, the pensioners had to settle for a tea at a nearby garden centre. Buglers yesterday declined to comment on the incident but it is understood the coach driver was using her own sat-nav system rather than one supplied by the company.

The coach was one of a succession of heavy lorries, caravans and even a stretch limo which have tried to squeeze down the lane over the past two years only to become stuck.

Ian McDonald, 70, a retired transport manager who lives on Rosemary Lane, said: "There's not a day goes past when a big lorry or similar vehicle doesn't go down here. We can only assume that these sat-nav systems are telling drivers that our road is the quickest or shortest route from Chepstow, which it isn't."

Residents have written to their local authority in the hope that Rosemary Lane will be removed as a suitable route in information provided to mapping companies, who in turn supply sat-nav operators such as TomTom, Garmin and SmartNav.

Transport experts said part of the problem lay in the inability of satellite navigation systems to distinguish between the types of vehicle being used, from a hatchback to a 38-ton lorry.

Kevin Delaney, of the RAC Foundation, said there was an onus on manufacturers to provide information on routes unsuitable for large vehicles. "But at the same time, drivers also have a responsibility to not just blindly follow the instructions given to them by this kit. Motorists should know when a road isn't looking right," he said.