Front page · Cosyford Tunnel
Under the river we go: the tunnel machine digging Cosyford a railway, one ring at a time
A giant boring machine, a tunnel under the estuary and the odd fossil in the way. Dr Ivy Delve has dug under three rivers and one very surprised golf course, and she says this is her favourite yet.
It is all drawn cut away, like a page in a book: the town and the estuary and the hill on top, the clay, sand and chalk in their layers underneath, and the machine in her tunnel, which the school got to name. Hold the button and she pushes, the great red cutter turning and the spoil riding back on the belt. Every sort of ground wants its own push. Ease off in soft sand or she sinks, shove hard in the band of rock or she barely moves, and do not overdo it in sticky clay or the cutter clogs. The ground keeps nudging her off the orange line, so you steer her back by the laser target in the cab.
Every few metres it is ring time. From inside the tunnel you swing the erector arm round with each curved concrete segment, let it settle over its slot and let go: clunk, and the bolts spin in. The key goes in last, at the top. Up in the yard, the muck comes out of the shaft in little carts, and you throw the points to send the clay, the sand and the rock to their bays. The quarry takes it from there.
Now and then the cutter comes up against something special, and everything stops. A trowel for the loose clay (careful, it chips), a brush as you get close and a puff of air for the dust, and out comes an ammonite, a mammoth tusk, or a bead necklace left by people who lived here thousands of years ago. Each one goes in the tunnel’s finds cabinet. And at the end of every stretch there is a last wall: hold on, push her through, and the daylight floods in to cheers. Finish the whole tunnel and the first train runs, under the boats and out through the hill.
