Editing Through arch bridge (section)

==Construction sequence==
[[File:Frederick Douglass Bridge construction 2020b.jpg|thumb|The [[Frederick Douglass Memorial Bridge]] under construction in 2020.  The partially completed arch is supported by wires attaching it to the completed arch behind it.]]
In some locations it is not practical to support the arch from beneath during construction.

In modern construction, temporary towers are erected and supported by cables anchored in the ground. Temporary cables fly from each side to support arch segments as they are constructed. When the arches are almost complete a jacking bridge is placed over or beneath the gap to force the arches apart, whence the final section is constructed in place or lifted into position.

[[File:Runcorn-Widnes bridge - geograph.org.uk - 2784577.jpg|thumb|The [[Silver Jubilee Bridge|Runcorn–Widnes Bridge]] under construction in-between the [[Widnes–Runcorn Transporter Bridge]] and the lattice truss [[Runcorn Railway Bridge]].]]

In some cases, this type of arch has been created by constructing [[cantilever]]s from each side, with the shoreside ends bolted securely down into heavy piers. The incomplete channel ends are then constructed toward each other and either filled by construction or by lifting a prefabricated center section. This type of construction was used in the [[Sydney Harbour Bridge]] illustrated above, with the supporting cables to the higher side of the arches removed after completion.