Road tunnel gets 'smart' with vertical crop farm

OKCHEON, South Korea - Behind a blue wall that seals a former highway tunnel stretches a massive indoor farm bathed in rose-tinted light.

Fruits and vegetables grow hydroponically - with no soil - in vertically stacked layers inside, illuminated by neonpink LEDs instead of sunlight.

Operators of this high-tech facility in South Korea say it is the world's first indoor vertical farm built in a tunnel. It's also the largest such farm in the country and one of the biggest in the world, with a floor area of 2,300 square meters, nearly half the size of an American football field.