I'm gonna guess since the transformer bank you are referring to is (a) already in use due to the fuses in place and (b) only 300kVa (3-100's), that these chargers will receive power from a new and much larger service. If Guacahummus can find some drawings we can certainly tell if its a pad or pole mount service.
But I do agree, pole mounted services do come online rather quickly...unless we bring up the Humble SC next to IAH airport in Houston which has been sitting for weeks waiting for the service to be connected to the overheads.