The Cassair Connector Project, a 100-million-dollar upgrade from arterial city street to freeway, made use of both precast and site-cast concrete in several different structures. The largest concrete structure in the project is a 2,394-foot-long reinforced concrete twin-arch tunnel. The tunnel has 35 double-barreled segments, each about 68 feet long, 49 feet wide, and 16 feet high. The tunnel's heavily reinforced slabs serve as both structural slabs and finished pavement for the tunnel. Eighteen months were allowed for construction, with only 10 months available for actually pouring the tunnel segments.
The project schedule called for completing two pavement slabs, one footing, and one tunnel arch segment per week. For each twin-arch pour, the contractor used two pumps, each having output capacities of 200 cubic yards per hour. When slab access was limited, a pump with a 52-meter boom was used to reach the pour from a nearby road. To save forming costs, ensure segment uniformity, and speed tunnel construction, two traveling steel forms were built for the project, one for each arch. Large enough to cast one tunnel segment, each form was reused 35 times.
