The Truck and Lane impact factors are applicable to the Service I, Service III and Strength I Limit states. The Strength II Limit State impact factor is specifically applied only to the Permit Trucks selected for Strength II live load analysis. The Fatigue Impact Factor is used only for Fatigue I Limit State. The Fatigue I Limit state with a Live Load Factor of 1.50 applied to a Fatigue truck is required to be run and prestressed concrete compression due to 50% (Dead Load + Prestress) + 1.50 *Fatigue Load checked.