Tri-partite precast arches (TechSpan) custom designed as required may be adapted to any situation.

Nowadays continuous curved molds are used instead of the farmer hinged molds which greatly simplifies production and results in an enhanced esthetic appearance.

If we examine the antifunicular load (the compressed arch sections) and the Marston effect, the exact shape of the arch and corresponding truss can be designed even when it is far below the surface.

In the precast arches design, the truss for all the voussoir phases includes: forms strip, transport, manipulation on work, assembly, different levels of land fill and commissioning.

There are various solutions depending on the situation; small independent foundations may be placed on either side of the arch (small spam arches or arches close to the surface) or a continuous foundation running the length of the spam may be used large spams or arches far below the surface.

Each segment of the arch is produced in a horizontal position, with the interior facing the mold in order to ensure a smooth finish. Elements necessary for the transportation and rates manipulation of the segments are introduced during the casting process.