Allow some allowance for rounding errors

Author: peternewell

Source/Orts.Simulation/Simulation/RollingStocks/MSTSWagon.cs

@@ -2178,7 +2178,8 @@ private void UpdateLocomotiveLoadPhysics()
                         // Thus the loco weight only changes as boiler level goes up and down, and coal mass varies in the fire
                         {
                             MassKG = LoadEmptyMassKg + Kg.FromLb(SteamLocomotiveIdentification.BoilerMassLB) + SteamLocomotiveIdentification.FireMassKG + +(SteamLocomotiveIdentification.CurrentTrackSandBoxCapacityM3 * SteamLocomotiveIdentification.SandWeightKgpM3);
-                            MassKG = MathHelper.Clamp(MassKG, LoadEmptyMassKg, LoadFullMassKg); // Clamp Mass to between the empty and full wagon values        
+                            var MassUpperLimit = LoadFullMassKg * 1.02f; // Allow full load to go slightly higher so that rounding errors do not skew results
+                            MassKG = MathHelper.Clamp(MassKG, LoadEmptyMassKg, MassUpperLimit); // Clamp Mass to between the empty and full wagon values        
                         // Adjust drive wheel weight
                             SteamLocomotiveIdentification.DrvWheelWeightKg = (MassKG / InitialMassKG) * SteamLocomotiveIdentification.InitialDrvWheelWeightKg;
                         }
@@ -2224,7 +2225,8 @@ private void UpdateLocomotiveLoadPhysics()
                     {
 
                         MassKG = LoadEmptyMassKg + (DieselLocomotiveIdentification.DieselLevelL * DieselLocomotiveIdentification.DieselWeightKgpL) + DieselLocomotiveIdentification.CurrentLocomotiveSteamHeatBoilerWaterCapacityL + (DieselLocomotiveIdentification.CurrentTrackSandBoxCapacityM3 * DieselLocomotiveIdentification.SandWeightKgpM3);
-                        MassKG = MathHelper.Clamp(MassKG, LoadEmptyMassKg, LoadFullMassKg); // Clamp Mass to between the empty and full wagon values  
+                        var MassUpperLimit = LoadFullMassKg * 1.02f; // Allow full load to go slightly higher so that rounding errors do not skew results
+                        MassKG = MathHelper.Clamp(MassKG, LoadEmptyMassKg, MassUpperLimit); // Clamp Mass to between the empty and full wagon values  
                         // Adjust drive wheel weight
                         DieselLocomotiveIdentification.DrvWheelWeightKg = (MassKG / InitialMassKG) * DieselLocomotiveIdentification.InitialDrvWheelWeightKg;