Dublin Bus commuters will soon know exactly how long they will have to wait for the next bus with the launch of the eagerly awaited electronic real-time information system at a dozen stops across the city.

Originally supposed to be introduced before Christmas but delayed because of the bad weather, the high-tech system will be rolled out throughout the year to include 450 of the busiest bus stops in the capital.

A spokesman for the National Transport Authority, which spearheaded the project along with Dublin Bus and Dublin City Council, said it hoped to introduce the high-tech system in Cork, Galway, Limerick and Waterford by next year.

The total cost of the system is €6.5m, just 3c per passenger, a spokesman for the NTA said. Annual maintenance will up to €250,000 a year.

The 12 selected stops which will go live next month have already been the subject of tests. So far, the system has proved accurate, the NTA spokesman said. They include Harrington Street, Donnycarney, Harold's Cross and Ballymun.

Under the system, each of the company's 1,000 buses will be fitted with a GPS-style locator system. This relays information on the location of the bus to a Dublin Bus control centre. Operators then forward that information to the screen at the bus stop, which is updated every 30 seconds.

Dublin Bus said the GPS system would operate on buses in five out of seven depots, with the remaining two expected to come on stream by the end of March.

Commuters won't have to move from the comfort of their home or office to track their bus. Each bus stop using the real-time system will carry a number. Once commuters input this number on a designated website, the real-time information for that particular bus stop will be relayed on screen.

The NTA spokesman stressed that the aim of the system was to provide accurate information to commuters and that the arrival times on the sign could change as buses encounter problems.

Real-time information for train and tram passengers was easier as only un­expected events could cause delays, he said. "The same facility for buses is more complicated given the volume of individual vehicles involved, their number of stops, traffic patterns etc."

He said the benchmark in other European cities was to achieve 90%-plus accuracy. "The intention with this new system is to exceed this."