An all-night bus service following the route of Glasgow's Subway system is launched tonight.

The Nightrider service will ferry revellers and workers from 11.40pm on Friday and Saturday nights until the Subway re-opens the next morning. On Sundays, it will operate from 6pm until 11.30pm.

The publicly-funded service, launched by Strathclyde Partnership for Transport, will run for an initial 15 months and be operated by First Bus.

Six buses will provide clockwise and anti-clockwise journeys every 20 minutes along the route of the Subway circle. The buses will stop at each station, just like the underground.

All buses will be accessible to wheelchair users and equipped with CCTV cameras.

SPT has paid First £296,303 to run Nightrider and all the £2 flat fares will go back to the transport authority. However, the authority only expects to get back around half of its contribution.

The service will be evaluated during its lifespan to assess patronage, with the hope it will become a permanent fixture.

SPT admits a combination of factors has forced its hand on Nightrider, including Glasgow's booming night-time economy, the reluctance of private bus firms to operate night services and the inability to operate the Subway beyond current hours due to staffing and maintenance issues.

Its chairman, Alistair Watson, admits the system still operates in "1970s hours'' but is forced to do so largely because of a 19th century infrastructure.

SPT also claims that the cost of operating the Subway until 11pm on Sunday only, when it shuts at 6pm, would run to £540,000 for a year.

Another potential benefit would be the quick dispersal of people from the city centre, lingering revellers and massive taxi queues being one of the main sources of city centre late-night disorder.

SPT's assistant chief executive, Gordon Maclennan, said: "We know there is a demand for better late-night public transport in Glasgow, particularly for people trying to get home after a night out.

"We believe the Subway Nightrider will help support Glasgow's thriving nightlife by offering a greater choice of transport in the city overnight. It will also benefit shift workers making their way to work for an early start."

Mr Watson added: "There is a gap with night bus services in the city, especially with some having been taken off.

"There's also a lot of public pressure to keep the Subway going all night. But that's a very costly option and we need to do maintenance.

"This service means there will now be round-the-clock public transport in the city at weekends. It will bridge the gap between the Subway closing at night and reopening the next morning at a much less cost."