As air congestion and airport overcrowding become familiar features of travelling in Europe, France and Britain have been struggling to find a solution to cope with the increasing popularity of air travel.

Paris-Chaulnes

Estimated cost: 50bn francs (�4.7bn) Forecast passenger traffic: 140 million by 2020 Will take 15 years to build

Their respective projects have generated comparable controversy.

In France the government has toyed with the idea of building a third airport for over a decade, while London's Heathrow airport has spent almost as long battling for the construction of a fifth terminal (T5).

Now the French Government has finally announced the site of a new facility outside Paris, while a decision about the construction of Terminal Five was expected on Tuesday.

Heathrow's T5

Estimated cost: �2.5bn (26.5bn francs) Forecast passenger traffic: 140 million by 2010-11 Should be complete by 2006-7

Forecasts of increased passenger traffic over the next two decades have spurred governments into action.

Official figures say that 140 million passengers will travel through London's airports by 2010/2011 and Paris by 2020.

But the figures themselves are contentious, with French Greens - who are part of France's ruling left-wing coalition government - pointing to the current travel industry crisis following the 11 September attacks in the US.

It is "probable that the cost of air transport will be higher in future years and that [forecast air traffic] growth will perhaps not be that expected," says French Environment Minister Yves Cochet.

Location, location

Anti-T5 campaigners also say the latest plane crash near New York's JFK airport strengthens the case against building a new terminal near a densely populated area.

Some say new airports should be away from built-up areas

People living near Paris's two existing airports - Roissy-Charles de Gaulle (CDG) and Orly - made a similar point when they demonstrated in favour of a third Paris airport away from residential areas earlier this month.

Their case has been reinforced by the Concorde crash last year which reignited the debate about air congestion, as investigators blamed the accident on a strip of metal left on the runway by a previous plane.

Hence, the new Paris site of Chaulnes, chosen over seven other contenders, is located 125 km (78 miles) north of Paris in a little populated area.

It will be connected to Paris by two existing motorways and a nearby TGV station, but a direct rail link is also likely to be built.

Likewise, the Heathrow association for the control of aircraft noise (Hacan) in the UK says any new airport facility in the south-east of England should be sited away from built-up areas.

John Stewart, chairman of Hacan, says: "If expansion is required, the government needs to look at building new airport capacity where people don't live... That probably means a coastal airport."

French Greens argue in favour of developing existing installations instead of building new ones. They propose the following:

• transferring freight traffic from CDG to Vatry, an existing cargo terminal in the Marne area, 120 km from Paris
• developing existing regional airports
• more European TGVs
• banning night flights

Night flights nightmare

Indeed another important point of contention in both countries is noise pollution. A recent study shows high noise levels cause stress and high blood pressure in people living near airports.

A recent ruling by the European Court of Human Rights bans flights to and from Heathrow between 2300 and 0600 which "infringe residents' rights to a good night's sleep", under article eight of the Human Rights Convention.

High noise levels are said to cause stress and high blood pressure

However, the ruling is not binding on the UK Government, although the convention on which it is based is now in enshrined in UK's own Human Rights Act.

The British Airports Authority is currently not allowed to increase the number of night flights, and it must provide new public transport links to cut down on the weight of traffic in the area.

Local Roissy and Orly residents who actively supported the creation of a third airport in Paris have also been pushing for night flights - between 2200 and 0600 - to be banned at existing airports as well.

Currently, night flights are banned at Orly between midnight and 0500, while they are allowed at CDG.

But switching to early morning flights can prove expensive. To move British Airways flights into Heathrow to daytime slots could cost between �20m-�30m a year, says the London Chamber of Commerce.

Even if it clears the final hurdle for approval, the main T5 building, along with new parking and other facilities, will not be completed until 2006-7.

As for the third Paris airport, it is not expected to be finished until 2015 at the earliest and probably not before 2020.

So congestion relief remains some way off and passengers' patience will be taxed for a few more years to come.