>>8196928 (pb)
Keystone Construction - Details
A heavily timber-supported wooden semi-circle form is built and then the two halves of the semi-circle are constructed simultaneously with precisely carved and angled stone "arcs" carefully positioned into place.
When completed, the keystone is lifted vertically with block and tackle or small crane by grabbing the notched top of the stone. It is then moved and gently lowered into the remaining space which "locks" the two semi-circle halves. The supporting form-work is carefully removed to allow the stones to make the final micro-adjustments to fully lock the arch into place. The arch will now be able to be loaded vertically with the remainder of the archway.