Soggy Subway Plans Advance In Amsterdam

"Construction of a new "North-South" line for this city of canals and rivers began in 2003, and is presenting Dutch engineers, famed for their ingenuity in keeping this waterlogged nation dry, with devilish challenges."

"The solution: 7,000 mirrors hung in clusters of three on buildings along the 2.4 miles of the route that's underground. Measuring devices shine infrared beams onto each mirror once an hour, measure the reflection, and feed data into a central computer."

"After triangulating, the computer raises the alarm if any building shifts more than 0.5 millimeters in any direction."

"Scheduled for completion in 2013, the $2.4 billion project stretches 5.9 miles in all and will transport an estimated 200,000 people daily, adding a new dimension to Amsterdam's traffic of bicycles, trams, cars, taxis, buses and boats."

"The biggest technical challenge is building a subway stop directly beneath the city's main train station - a landmark 19th century building - while it remains in use."