Which of the following methods to reduce cantilever moment is better in incremental launching, (i) temporary nose, (ii) mast or (iii) auxiliary piers?

The use of mast is an alternative to temporary nose. From practical point of view, the use of mast requires continual adjustment of forces in the guys when the superstructure is pushed forward. On the other hand, the implementation of temporary nose system does not require much attention during operation.

For large span lengths (>50m) it is advantageous to adopt auxiliary piers because this helps reduce the central prestress required. However, it may not be economical for auxiliary piers with height more than 40m.

This question is taken from book named – A Closer Look at Prevailing Civil Engineering Practice – What, Why and How by Vincent T. H. CHU.