Once the first cycle is complete, the forms are raised by crane once again and moved either to the next level or to a room adjacent to the one just completed.
A typical two-day cycle is shown in Figure 4.12. On the first day, two rooms have been poured while the third room has ended at a construction joint. If the third room is of the same size and
dimensions, then a waiting tunnel form is typically used. On the second day, the pouring is started at the construction joint on the third room. The fourth room is also poured, while the fifth room is where the construction joint is now located.
Once one floor is complete, the cycle is then repeated for the next level starting above the first room to be cast. This type of cycle uses a third tunnel form that is always waiting for the pouring to catch up.
Another type of forming cycle uses an ‘‘end wall’’ tunnel wall after the second room. This system still provides the location for the construction joint, but is used when a corridor or different sized room is to be formed next. As seen in Figure 4.13, an end wall has been used to terminate the first day pouring and provide a construction joint at the necessary location.
On a typical tunnel form project, anywhere from 10 to 20 workers may be required to complete the work cycle. The size of the project usually determines the number of workers. Usually five to six rooms can be completed each day, using 10 to 20 workers, with five or six tunnel forms and one crane.