Of all the bungled projects, the Berlin airport is the biggest embarrassment.
The initial plan foresaw building a stately airport that would be financed by private investors and replace the city’s two Cold War airports — Tegel in former West Berlin and Schoenefeld in what was the communist east.
After a series of disputes with private investors, the city, state and federal governments eventually took over the airport project. In 2006, costs were estimated at 2 billion euros, but after four delays, the figure spiked to 4.4 billion euros.
Companies like Air Berlin, Germany’s second biggest carrier, have been severely affected by the delays and are suing for lost revenues. Small businesses like coffee shops, restaurants, retail stores or bus operators — who had already hired staff and invested in new stores at the airport — are facing bankruptcy.
Twitter users asked the mayor to ‘‘please open this gate,’’ playing off President Ronald Reagan’s famous 1987 appeal to Moscow to ‘‘tear down’’ the Berlin Wall.
And by the time the airport finally opens, it may face a new headache.
Some aviation experts are warning that by its inauguration date, the airport will already be too small to handle the rising number of passengers. The nearly 3.9 million square foot (360,000 square meter) airport complex was designed to handle 27 million passengers. But the existing two city airports handled 25 million passengers last year — and the city keeps attracting more visitors every year.
‘‘The airport is too expensive, too small and too much behind time,’’ said aviation expert Dieter Faulenbach da Costa, who recently caused a stir when he proposed that the airport ought to be torn down.
In an effort to salvage the mess, Hartmut Mehdorn, the hardnosed former boss of the German railway system with a reputation for turning around failing corporations, was named chief executive of the airport in early March.
‘‘The whole world says: it’s not possible at all,’’ Mehdorn said when he took over. ‘‘I say: It should be possible.
‘‘I just don’t know how yet.’’