Index: DamEngine/trunk/src/Deltares.DamEngine.Data/General/Gauges/GaugePLLine.cs
===================================================================
diff -u -r4000 -r4029
--- DamEngine/trunk/src/Deltares.DamEngine.Data/General/Gauges/GaugePLLine.cs	(.../GaugePLLine.cs)	(revision 4000)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/General/Gauges/GaugePLLine.cs	(.../GaugePLLine.cs)	(revision 4029)
@@ -19,7 +19,7 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
-using System;
+using System.Text;
 using Deltares.DamEngine.Data.Geometry;
 
 namespace Deltares.DamEngine.Data.General.Gauges
@@ -43,7 +43,7 @@
 
         public override string ToString()
         {
-            return String.Format("({0}, {1}, '{2}', '{3}')", X.HasValue ? X.ToString() : "?", Z.HasValue ? Z.ToString() : "?", GaugeIDX, GaugeIDZ);
+            return $"({(X.HasValue ? X.ToString() : "?")}, {(Z.HasValue ? Z.ToString() : "?")}, '{GaugeIDX}', '{GaugeIDZ}')";
         }
     }
 
@@ -61,13 +61,14 @@
 
         public override string ToString()
         {
-            string result = String.Format("{0} | ", PlLineType.ToString());
+            var result = new StringBuilder($"{PlLineType.ToString()} | ");
             foreach (GaugePlLinePoint point in Points)
             {
-                result += point + ", ";
+                result.Append(point);
+                result.Append(", ");
             }
 
-            return result;
+            return result.ToString();
         }
     }
 }
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Data/General/Sensors/Sensor.cs
===================================================================
diff -u -r4000 -r4029
--- DamEngine/trunk/src/Deltares.DamEngine.Data/General/Sensors/Sensor.cs	(.../Sensor.cs)	(revision 4000)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/General/Sensors/Sensor.cs	(.../Sensor.cs)	(revision 4029)
@@ -22,6 +22,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Text;
 using Deltares.DamEngine.Data.Standard;
 
 namespace Deltares.DamEngine.Data.General.Sensors
@@ -202,27 +203,27 @@
         {
             get
             {
-                var res = "";
+                var res = new StringBuilder("");
                 foreach (PlLineType plLineType in plLineTypes)
                 {
                     switch (plLineType)
                     {
                         case PlLineType.Pl1:
-                            res = res + "1; ";
+                            res.Append("1; ");
                             break;
                         case PlLineType.Pl2:
-                            res = res + "2; ";
+                            res.Append("2; ");
                             break;
                         case PlLineType.Pl3:
-                            res = res + "3; ";
+                            res.Append("3; ");
                             break;
                         case PlLineType.Pl4:
-                            res = res + "4; ";
+                            res.Append("4; ");
                             break;
                     }
                 }
 
-                return res;
+                return res.ToString();
             }
             set
             {