Many people using Heathrow Terminal 4 will soon find it tougher to reach. The last Tube trains to the terminal for some time will run two months from today. From 7 January, the 18-year-old loop on the Piccadilly Line from Hatton Cross via Terminal 4 to Heathrow Central will be suspended for nearly two years. The reason: work to extend the line to the new Terminal 5, which is due to open in 2007. Transport for London says the closure is necessary "for essential safety reasons".

Terminal 4 began as BA's long-haul hub, but it now handles a large number of its European flights as well. It is also the home of BA's erstwhile partner, Qantas, plus Air Malta, Kenya Airways, KLM Royal Dutch Airlines and SriLankan.

The 2,500 travellers who currently take the Tube to Terminal 4 each day will have two main alternatives between January 2005 and September 2006. The first is to travel to Heathrow Central and connect to the Heathrow Express for the free five-minute train ride to Terminal 4. Those without luggage will find it easier and quicker to alight at Hatton Cross and take the free shuttle bus to Terminal 4.

The Piccadilly Line's general manager, Mike Challis, claims that journeys will only take about five minutes longer than they do now. But the advantages of the extremely convenient Tube station in Terminal 4 will be lost, which suggests that travellers should allow an extra 10-15 minutes for their journeys.

Ironically, passengers heading for Heathrow Central, which serves Terminals 1, 2 and 3, should arrive five minutes earlier because the detour via Terminal 4 will be eliminated. When Terminal 5 opens, it will have its own station on the Piccadilly Line. Since Terminal 4 station is used by just one passenger to Heathrow Central's nine, there is speculation that it will never re-open. But Transport for London insists that the current Terminal 4 to Heathrow Central loop will be reinstated in under two years.

* Next July, the Heathrow Connect local service is expected to start, offering an alternative route to Terminals 1, 2 and 3. Like the Heathrow Express it will start from Paddington, but it will call at all local stations to Hayes and Harlington, functioning as an ordinary train, before travelling underground to Heathrow Central. The journey will take around 30 minutes compared to 15 on the Express, but fares are expected to be much lower than the £14 each-way charged on the high-speed link.