Twin tunnels, single bores and megabores – Local subway planners face choices on what will work best for new lines

Each new subway tunnel is as unique as its surrounding neighbourhood and geology. While six-metre, twin tunnels were once considered standard, more recent technology has made larger, single tunnels possible. This article reviews the different sizes of tunnels and the factors that go into choosing one. Let’s get out the tape measures - the really … Continue reading Twin tunnels, single bores and megabores – Local subway planners face choices on what will work best for new lines

The art and science of building subway tunnels – One size doesn’t fit all

In the dark, all subways tunnels can look alike, but each one is unique. Some are bored and others are mined. The length of a line and the geography of the neighbourhoods it goes through influences how a tunnel is created. A whole series of decisions about each tunnel must be made before construction can … Continue reading The art and science of building subway tunnels – One size doesn’t fit all