In October of 2004 (dry) and April of 2005 (wet), two vehicle impact studies were conducted at Fort Riley, KS on two different soil types using different 4 military vehicles to determine vegetation and terrain disturbance. Global positioning system (GPS) vehicle tracking systems (VTS) were mounted on the vehicles to determine vehicle dynamic properties. A total 32 impact plots (8 for each vehicle) were conducted during each study period at Fort Riley, Kansas. The spirals were split between two different soil types (loamy upland and clay upland). The vehicles tested were the M998 (HMMWV), M977 (HEMMT), M113 (APC), and M1 (Combat Tank). Comparisons of wet vs. dry vehicle impacts were determined for each vehicle.