A box girder for a sloped end section of the top chord is being hoisted into position by a crawler crane with a red boom in the center of the picture. Other box girder sections are still on the arena floor. The two vertical white box trusses on the right of the photograph are erection towers at the queen post positions that provide temporary support for all structural members. (Click here or on photo for full size photo.)

The sloped end section of a concrete top chord is in its final position, spanning between the outside wall of the arena and an erection tower. The center top chord section has not yet been placed. The near ends of open web trusses that support the roof come together at the queen post position, so that no roof load is directly supported by the concrete box girder top chord. This puts the concrete top chord in pure compression, another innovation. (Click here or on photo for full size photo.)

The concrete box girder center section is being placed between its two sloped concrete box girder end sections to form the complete top chord of the tied-arch truss. The two workers standing on the box girder near the upper center of the picture give an idea of scale of the structural members. (Click here or on photo for full size photo.)

This view from further away of the placing the concrete box girder center section shows the roof framing that has already been erected on its far side. (Click here or on photo for full size photo.)