By comparing various types of machines for excavation, for example, power shovels are generally found to be the most suitable for excavating from a level surface and for attacking an existing digging surface or one created by the power shovel; furthermore, they have the capability of placing the excavated material directly onto the haulers. Another alternative is to use bulldozers for excavation.
The choice of the type and size of haulers is based on the consideration that the number of haulers selected must be capable of disposing of the excavated materials expeditiously. Factors which affect this selection include:
1. Output of excavators: The size and characteristics of the excavators selected will determine the output volume excavated per day.
2. Distance to dump site: Sometimes part of the excavated materials may be piled up in a corner at the job-site for use as backfill.
3. Probable average speed: The average speed of the haulers to and from the dumping site will determine the cycle time for each hauling trip.
4. Volume of excavated materials: The volume of excavated materials including the part to be piled up should be hauled away as soon as possible.
5. Spatial and weight constraints: The size and weight of the haulers must be feasible at the job site and over the route from the construction site to the dumping area.