Location of Relay/Switching Cabinets?

What is the spacing where one cabinet can service more than one switch? How far from a cabinet can the switch be?
Of course, the same applies to the cabinets supporting signals.. What determines the size of a cabinet - obviously the number of switches and signals but is there any criteria?

I don't know exactly, but the distance appears to be 10 to 20 feet and about 10 feet from the track side its self. Regarding signal and switch controls, it probably depends upon the size of the cabin. Some are pretty big and I'll assume that they can handle a lot more relays than the smaller ones can. For the most part, I look at Google Earth, and use that for judgement as to where to place things like that and how many to place.