Great Britain's first amphibious bus service has hit a slight snag in testing - a component failure halting the Stagecoach Amphibious Bus in its third crossing of the river Clyde between Renfrew and Yoker in Scotland. Proposed as a replacement for a ferry service that's set to close down next month, the "amfibus" is designed to deliver passengers across the Clyde with minimal transition time between its regular coach mode and jet-powered water crossing mode.

Based on a regular Volvo bus chassis, the 12/8 meter amfibus incorporates a hull and flotation airbags to allow it to float on the water. On the road, it's controlled through a traditional accelerator and brake pedal, and on the water this switches to a pair of water jets. The engine is Euro 5 compliant, and can deliver a max speed of 60mph on and or 8 knots on water with a max passenger count of 50. It uses ramps to enter and exit the water.

A slight hitch

The bright yellow Stagecoach amfibus ground to an embarrassing halt on one of its first Clyde crossings on Monday. According to Stagecoach representatives, the bus was stopped after a clunking, grinding noise as it went to exit the river. The noise turned out to be a loose airbag at the rear - the coach is elevated out of the water by a series of such flotation devices connected to the suspension, and one of them had worked its way loose.

So, not a serious fault but certainly one to raise a few questions as the British government tries to decide whether the amfibus is worth subsidizing as a replacement for a financially troubled ferry service in the area.

The small ferry was losing as much as UK£400,000 per year due to lack of usage and the presence of a couple of bridges not too far from the crossing spot. Stagecoach has proposed that its UK£700,000 amphibious bus would be more of a drawcard, due to its tourist attraction value plus the fact that it travels non-stop from Braehead, through Renfrew, across the Clyde river to Yoker and on to Clydebank by road.

The test coach has already endured several weeks of use in Rotterdam Harbour in the Netherlands, and the technical setback has already been resolved - but it remains to be seen whether the British government will share Stagecoach's optimism that amphibious buses are a viable way of opening up new transport routes between Britain's many riverside towns.