Showcrop, 2A used to be referred to as modified.
2A is a Penndot standard and is federal highway approved as far as I know.
I have to disagree with you on compaction of gravel, aggregate.
• This material has a 1-1/2 inch topsize and is a clean material.
AASHTO #57 washed
• Used in ready-mixed concrete and hot mix asphalt
• Also used for driveways, walkways, and drainage
• Clean material that does not compact well.
Here is the Redneck test results. Place gravel of any size on a driveway, roll it well. Then take your pickup truck to the gravel driveway and mash the throttle. Gravel will fly everywhere and you will have a hole or a rut.
Now take 2A Modified and roll it and repeat the spin test. The result will be that the tires just spin on the surface and do not displace the material.