Add TpEPA and TpEDBA, when units are imperial.

TpEPA = Tons per Equivalent Powered Axles.
TpEDBA = Tons per Equivalent Dynamic Brake Axles.

These metrics are more accurate than HP per Ton, as they are based on
tractive effort.

The calculations are based on Union Pacific practices. UP uses a
standard axle of 10'000 lbf tractive effort or dynamic brake force.
For example a GP40-2 is 5.0 EPA, an SD40-2 is 7.1 EPA. Both have the
same HP (and thus result in the same HP-per-Ton).

Also renamed one variable.

Author: rwf-rr

Source/RunActivity/Viewer3D/Popups/HelpWindow.cs

@@ -1192,12 +1192,14 @@ private void AddAggregatedTrainInfo(Train playerTrain, ControlLayout scrollbox,
             string numEngines = ""; // using "+" between DPU sets
             int numCars = 0;
             int numAxles = 0;
-            var massKg = playerTrain.MassKg;
+            var totMassKg = playerTrain.MassKg;
             string sectionMass = ""; // using "  +  " between wagon sets
             var lengthM = playerTrain.Length;
             var maxSpeedMps = playerTrain.TrainMaxSpeedMpS;
             float totPowerW = 0f;
+            float totMaxTractiveEffortN = 0f;
             string sectionMaxTractiveForce = ""; // using "  +  " between DPU sets
+            float totMaxDynamicBrakeForceN = 0f;
             string sectionMaxDynamicBrakeForce = ""; // using "  +  " between DPU sets
             float maxBrakeForceN = 0f;
             float lowestCouplerStrengthN = 9.999e8f;  // impossible high force
@@ -1231,7 +1233,9 @@ private void AddAggregatedTrainInfo(Train playerTrain, ControlLayout scrollbox,
                     engCount++;
                     numAxles += eng.LocoNumDrvAxles + eng.GetWagonNumAxles();
                     totPowerW += eng.MaxPowerW;
+                    totMaxTractiveEffortN += eng.MaxForceN;
                     engMaxTractiveForceN += eng.MaxForceN;
+                    totMaxDynamicBrakeForceN += eng.MaxDynamicBrakeForceN;
                     engMaxDynBrakeForceN += eng.MaxDynamicBrakeForceN;
 
                     // hanlde transition from wagons to engines
@@ -1292,7 +1296,7 @@ private void AddAggregatedTrainInfo(Train playerTrain, ControlLayout scrollbox,
 
             line = scrollbox.AddLayoutHorizontalLineOfText();
             line.Add(new Label(labelWidth, line.RemainingHeight, Viewer.Catalog.GetString("Total Weight:"), LabelAlignment.Left));
-            string massValue = FormatStrings.FormatLargeMass(massKg, isMetric, isUK) + "    (" + sectionMass + ")";
+            string massValue = FormatStrings.FormatLargeMass(totMassKg, isMetric, isUK) + "    (" + sectionMass + ")";
             line.Add(new Label(line.RemainingWidth, line.RemainingHeight, massValue, LabelAlignment.Left));
 
             line = scrollbox.AddLayoutHorizontalLineOfText();
@@ -1319,17 +1323,37 @@ private void AddAggregatedTrainInfo(Train playerTrain, ControlLayout scrollbox,
 
             if (!isMetric)
             {
-                float hpt = massKg > 0f ? W.ToHp(totPowerW) / Kg.ToTUS(massKg) : 0f;
+                float hpt = totMassKg > 0f ? W.ToHp(totPowerW) / Kg.ToTUS(totMassKg) : 0f;
                 line = scrollbox.AddLayoutHorizontalLineOfText();
                 line.Add(new Label(labelWidth, line.RemainingHeight, Viewer.Catalog.GetString("Horespower per Ton:"), LabelAlignment.Left));
                 line.Add(new Label(line.RemainingWidth, line.RemainingHeight, string.Format("{0:0.0}", hpt), LabelAlignment.Left));
 
-                float tpob = numOperativeBrakes > 0 ? Kg.ToTUS(massKg) / numOperativeBrakes : 0;
+                float tpob = numOperativeBrakes > 0 ? Kg.ToTUS(totMassKg) / numOperativeBrakes : 0;
                 line = scrollbox.AddLayoutHorizontalLineOfText();
                 line.Add(new Label(labelWidth, line.RemainingHeight, Viewer.Catalog.GetString("Tons per Operative Brake:"), LabelAlignment.Left));
                 line.Add(new Label(line.RemainingWidth, line.RemainingHeight, string.Format("{0:0}", tpob), LabelAlignment.Left));
+
+                // The next two metrics are based on UP's equivalent powered axles and equivalent dynamic brake axles. These are based on
+                // tractive effort, and thus provide a more accurate metric than horsepower per ton. UP uses 10k lbf for a standard axle.
+                // TODO: EPA and EDBA should really be defined in the eng file, and not calculated here.
+                // TODO: It would be great to also show the minimum TpEPA and TpEDBA for the current train-path. But that is hard to calculate,
+                //       and should really be defined in the path file.
+
+                // tons per equivalent powered axle (TPA or TpEPA)
+                float tpepa = totMaxTractiveEffortN > 0 ? Kg.ToTUS(totMassKg) / (N.ToLbf(totMaxTractiveEffortN) / 10000f) : 0;
+                line = scrollbox.AddLayoutHorizontalLineOfText();
+                line.Add(new Label(labelWidth, line.RemainingHeight, Viewer.Catalog.GetString("Tons per EPA:"), LabelAlignment.Left));
+                line.Add(new Label(line.RemainingWidth, line.RemainingHeight, string.Format("{0:0}", tpepa), LabelAlignment.Left));
+
+                // tons per equivalent dynamic brake axle (TpEDBA)
+                float tpedba = totMaxDynamicBrakeForceN > 0 ? Kg.ToTUS(totMassKg) / (N.ToLbf(totMaxDynamicBrakeForceN) / 10000f) : 0;
+                line = scrollbox.AddLayoutHorizontalLineOfText();
+                line.Add(new Label(labelWidth, line.RemainingHeight, Viewer.Catalog.GetString("Tons per EDBA:"), LabelAlignment.Left));
+                line.Add(new Label(line.RemainingWidth, line.RemainingHeight, string.Format("{0:0}", tpedba), LabelAlignment.Left));
             }
 
+            scrollbox.AddHorizontalSeparator();
+
             line = scrollbox.AddLayoutHorizontalLineOfText();
             line.Add(new Label(labelWidth, line.RemainingHeight, Viewer.Catalog.GetString("Lowest Coupler Strength:"), LabelAlignment.Left));
             line.Add(new Label(line.RemainingWidth, line.RemainingHeight, FormatStrings.FormatForce(lowestCouplerStrengthN, isMetric), LabelAlignment.Left));