Boring machines cut through the earth leaving a hole from which workers can assemble a tunnel
AdvertisementInfographicsGoing undergroundReading Time:1 minuteWhy you can trust SCMP0Simon ScarrandAdolfo ArranzPublished: 12:00am, 3 Dec 2011Boring machines cut through the earth leaving a hole from which workers can assemble a tunnel AdvertisementAdvertisement
