During the time of construction, cracks are likely to develop in small diameter concrete pipes. Why?

During the construction of new pavement, vibratory roller and heavy equipment are needed to compact the filling material and bituminous material. These heavy equipment could generate very high impact load with short duration on the concrete pipes. It requires an extremely even and uniform support in order to safely support these loads. Therefore, it is not uncommon that construction vehicles are primary source of crack-producer and it usually results in the formation of circumferential cracks.

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