Satellite communications are becoming an increasingly important technology for the smooth running of public transport systems.

London Buses' plans to evaluate global positioning system (GPS) technology to replace its existing real-time vehicle tracking system is just the latest innovation.

'GPS is now enormously significant within the transport sector,' said Ian Tunnacliffe, senior analyst at Giga Research, Forrester.

'I think we are looking at a world where in 10 years time anything more complex than a lawn mower will be GPS-enabled,' he said.

While GPS is only now starting to become a mainstream technology, it is not new. The system was developed by the US government and is still owned by the US Department of Defense. It was only in the late 1990's that the US decided to release a less accurate version for commercial use.

The technology has been a huge success in transport applications across the world. Tunnacliffe says almost every commercial plane uses GPS and the major long distance bus companies in the US are also using it.

But the US government's ownership of the technology could be a problem - a decision to turn off all GPS reception was narrowly avoided at the onset of the conflict in Iraq.

GPS will also face its first competition in a few years, when the European Space Agency launches its Eur3.5bn euro (£2.4bn) Galileo satellite positioning system, with promises of a much more accurate system.

'In a few years time there will be two alternatives: GPS or Galileo, and the European view is two options must make things a lot more secure,' said Tunnacliffe.

Meta Group analyst Leis-Olof Wallin says Galileo will be a serious rival to GPS.

'GPS will be there until Galileo gets up into space. It's the only thing out there that will provide that level of precision as the mobile operators come onboard,' he said.

Galileo is expected to be operational in 2008, and in the meantime the continued swing towards GPS in the transport sector is expected to continue.

'If you have an application you want to role out in the next couple of years, you will have to go to GPS. But you need to be aware of what is coming and you should be designing systems so you could add Galileo capability at a later date.' said Tunnacliffe.

For London Buses, GPS represents a potential next step for its Automatic Vehicle Location (AVL) application.

The organisation has spent £40m on the system so far, installing radio systems on its 8,000 buses, microwave-based roadside beacons, and electronic 'Countdown' screens at bus stops.

Despite the fact that the project was approved in 1996, full roll-out is not yet complete. London Buses has been faced with moving targets as the fleet expands and London Mayor Ken Livingstone increases services and pledges to introduce new technology.

The organisation will have spent £50m on the AVL system when it finally installs 2,000 more Countdown signs across the capital, bringing the number to 4,000 by 2005/6.

Presently, the location of every bus on London streets is pinpointed by roadside beacons, which communicate their location to control systems at the capital's 80 garages and a central control system in Chingford.

Operators can regulate bus movements if they are too bunched up, ensuring the smoother running of services. In addition, information about when the bus will arrive is sent to some bus stops to alert passengers.

But, Melanie Alexander, business manager of the Technical Services Group in London Buses, says the system needs to be updated if it is to withstand increased demand.

'AVL is based on older technology, but it's still robust,' she said.

'There's new technology coming along and the radio system on the buses is now very old. With our expansion we are looking at 10,000 buses and the old system was never designed to cope with that.'

Alexander says no firm decision has yet been made on what technology will be used, but the organisation is considering the use of GPS-based technology and has started limited trials.

AVL is the biggest project of its kind in the world, and the potential endorsement of GPS would be a firm indication that satellite tracking systems are going to become part of everyday life.