Working platform
An engineered surface built up to provide a stable base of sufficient bearing capacity for a crane or other plant to work from, typically used where the natural or made ground alone is not adequate. A working platform is itself a piece of temporary works, and its design should be checked and certified before plant is brought onto it.
In practice
A working platform is a designed element, not a load of stone tipped and rolled. It has a specified thickness, material and construction, it is built to that specification, and it is certified before use — which is what separates a platform from a hardstanding somebody made. Mats and platforms are not alternatives: a platform provides the capacity, and mats spread individual feet onto it.
Where this comes from: UK temporary works practice. Note the term is also used in work-at-height contexts for a MEWP or scaffold platform; this entry is the ground-bearing sense.
Where it matters on site
Ask who certified it and to what capacity before planning a lift from it. A platform certified for one class of plant has not been certified for the piling rig that arrives next month, and platforms degrade — under traffic, after rain, after a trench is cut across them. The certificate describes the platform as built, not as it is today.