Madrid's centre faces paralysis from the 'tunnel of laughs'

Work has begun on the most ambitious and controversial building project to blight the Spanish capital in recent times. The gouging out of an eight-kilometre (five-mile) subterranean rail interchange at Puerta del Sol and Gran Via boulevard will paralyse the centre of Madrid for four years.

Work has begun on the most ambitious and controversial building project to blight the Spanish capital in recent times. The gouging out of an eight-kilometre (five-mile) subterranean rail interchange at Puerta del Sol and Gran Via boulevard will paralyse the centre of Madrid for four years.

Puerta del Sol, the central square through which every Madrileno is said to pass every day, will become a gigantic hole. Gran Via - the city's main artery - is to be chopped in two in front of the historic Telefonica building, and its metro station - one of Madrid's busiest - closed. Montera Street, which links these hubs of teeming humanity, will be closed and excavated, threatening grand 19th century buildings with compulsory purchase and destruction, and hundreds of shopkeepers with ruin.

Critics say the tunnel - known by the bitter nickname "Tunnel of Laughs" - is not even necessary, since it will run alongside an existing rail tunnel that already links Madrid's two rail termini: Chamartin in the north and Atocha in the south. And the city is already criss-crossed by one of Europe's densest metro systems, with numerous stations linking with the regional rail network.

Madrilenos are used to dodging chasms in the street, squeezing single-file through scaffolding, and blocking their ears to the sound of mechanical drills. But the unprecedented scale and length of this project leaves local people reeling with disbelief.

"We risk losing our business, and no one has explained to us the public benefits of these works," complained Baltasar Isar, who operates a newspaper kiosk in Puerta del Sol. Juan Martos, who runs a shoe shop, fears a collapse in the tourist trade. "It's one thing to stroll along a pavement window-shopping, and another to pick your way through building works," he said.

There have been reports of two subterranean lakes beneath the site, one of them 17 metres deep, and critics fear the works could result insubsidence and potholes. The presence of lakes would hardly be surprising in a city named Mayrit by its Arab founders - "place of many springs".

The vast time span for the project is difficult for "live today" Spaniards to grasp. "In four years you can take a degree, write one or two novels, see two football world cups and conceive a child that walks and talks," raged the writer Javier Marias. A city that celebrates its vibrant street life and thrives on tourism faces the devastating prospect of becoming a no-go zone for visitors.