We're in Dallas, Texas. 
It rarely freezes here. 
It rains a lot less than average. 
The ground is solid clay - hard and ungiving.

This environment allows us to choose some materials
and techniques that simply won't work in other places:

• We rest our ramp footings on 6" square wooden pads, directly on the ground.  In other areas, with softer ground and/or colder weather, it's important to dig and place a concrete foundation below the frost line.

• We deck our ramps with 4' x8' treated plywood.  In climates prone to freezing, this would be an extreme slip hazard.  Proper decking, with a slight spacing between the planks for drainage and traction, is more appropriate for locations with snow and ice conditions.