One of the farming properties where our recent Soil Expedition led us to was a Controlled Traffic Farming (CTF) operation in Central NSW. Soil pits were excavated across many soil types on the property including vertical cracking clays (Vertisol) to relatively structureless sands.
When digging the pits they were sited across the planting rows and wheel tracks. This provided a brilliant cross-section of the true effect CTF can have on subsoil condition
As can be seen in the above picture, the soil in the zone below the wheel track is significantly more compacted than the soil between the wheel tracks, with the soil becoming very hard and blocky in the wheel track zone.