With the UK government eager to begin taxing motorists based upon how much and where they drive, Transport for London announced yesterday that it has signed a £120 million (US $220 million) contract with Siemens AG to implement the world's largest GPS tracking system on the capital city's bus fleet. Siemens will install satellite monitoring units in 8,000 buses over the next four years. The network represents one of the largest and most complex urban transportation systems in the world.

London has pioneered the concept of taxing motorists for road use with its £5 (US $9) "congestion charge" to enter the city. Cameras snap images of every vehicle entering the city and those that have not paid the fee by midnight face a £100 (US $182) ticket. In the only voter referendum on the issue, Scotland's capital city rejected congestion charging by a 3-to-1 margin. Nevertheless, transportation officials in the country have expressed interest in expanding the road charge concept using a nationwide satellite tracking network.

Siemens officials say that this, "the largest project of its kind in the world," will also help keep buses on schedule and provide real-time updates on arrival times to riders waiting at bus stops.