A number of practical and geotechnical issues will determine the foundation selection on any given site. Any requirement for the tower crane to travel will determine the necessity for rails. The choice between the other foundation support systems will be governed by safety, economics and the prevailing ground conditions.
In general, where the required allowable soil bearing capacity is high, a deep foundation rather than a shallow base will be required. As a rule of thumb, if the required allowable bearing pressure is in excess of 200kPa a shallow foundation may not be practical. Clearly the final base design should be confirmed by the appropriate calculations.Where the permanent works foundation is being carried on piles, often a piled tower crane base will be selected.

Appropriate and sufficient ground investigation is vital to ensure the provision of adequate foundations. An understanding of the soil types, strength and variability of the volume of ground that will be required to support the foundations must be obtained. Any major changes in site level or excavations  near the proposed site of the crane should be identified. Investigations should also cover other relevant issues such as the location of services.
Geotechnical information for the crane foundation will often be obtained from the site investigation for the main construction. This should have included a desk study to identify past uses of the site and information on the soils and their parameters. Because the foundation levels should be similar for the crane and the main structure, the information should be transferable. However, it will be important to assess how relevant the information from the SI is if it has been obtained some distance from the tower crane location. In the absence of suitable information from the site investigation, specific investigation for the tower crane foundation may be necessary.