Can Europe's Railways Be Made Safe?

"It's a load of rubbish to call it a sophisticated attack," says British defense consultant Michael Dewar of the terrorist bombings in Madrid. The perpetrators had only to deposit their knapsacks of explosives fitted with simple timers and depart. "You and I could do it," Dewar says. The bad news is, railways are easy targets for terrorists — and defending them would require, at a minimum, airport-style delays that train travelers aren't willing to accept.

Europe has 228,000 km of track along which bombs could be planted. Big cities depend on commuter lines and subways to move huge...