Build from the top down. After each section of the structure was built, starting with the top of the arch, it was hoisted into the air, 30 metres at a time, and then horizontal supports were added.

In each pair, the trusses are fixed 2.6 m apart by horizontal and cross girders. The arch structure narrows from over 30 m wide at the abutments to around 10 m at the crown. Erection jitters ...