Using tunnel forms for the first time, Blake Construction Co. Inc., San Diego, built an 11-story, concrete-frame residence hall in 16 months. The hall, completed in September 1992, is located at San Diego State University. Blake completed the structure on schedule, building a 30-room floor every 6 days, on average.
Available in room-size or larger modules, tunnel forms are used to cast bearing walls and slabs in a single pour. The form modules are lifted into place by crane. Tunnel forms offer a large number of reuses in a structure having the same layout on every floor. They also help boost efficiency. Every worker performs the same job each day, so the crew becomes proficient quickly. The potential for error is reduced because the forms are pre-engineered. Tunnel forming also requires a smaller crew than does conventional wood forming, because workers do not have to assemble or tear down the forms.