Index: Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLineMetaImporter.cs
===================================================================
diff -u -re3f0e0861e4d1f5faa32280e837777e8755b67d6 -r7d38bc43c1be859f9a410ed99c6dacb2a6f58126
--- Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLineMetaImporter.cs	(.../ReferenceLineMetaImporter.cs)	(revision e3f0e0861e4d1f5faa32280e837777e8755b67d6)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLineMetaImporter.cs	(.../ReferenceLineMetaImporter.cs)	(revision 7d38bc43c1be859f9a410ed99c6dacb2a6f58126)
@@ -24,6 +24,7 @@
 using System.IO;
 using System.Linq;
 using System.Security;
+using System.Windows.Forms;
 using Core.Common.IO.Exceptions;
 using Core.Common.Utils.Builders;
 using Core.Common.Utils.Properties;
@@ -78,6 +79,8 @@
             targetItem.WrappedData.Id = assessmentSectionId;
             targetItem.WrappedData.ReferenceLine = selectedReferenceLineMeta;
 
+            targetItem.WrappedData.NotifyObservers();
+
             return true;
         }
 
@@ -163,6 +166,33 @@
                     }
                 } while (referenceLinesMeta != null);
             }
+
+            ValidateReferenceLineMetas();
         }
+
+        private void ValidateReferenceLineMetas()
+        {
+            var referenceLineMetasCount = referenceLineMetas.Select(rlm => rlm.AssessmentSectionId).Count();
+            var referenceLineMetasDistinctCount = referenceLineMetas.Select(rlm => rlm.AssessmentSectionId).Distinct().Count();
+
+            if (referenceLineMetasCount != referenceLineMetasDistinctCount)
+            {
+                var message = new FileReaderErrorMessageBuilder(shapeFilePath)
+                    .Build("De trajectid's niet uniek.");
+                log.Warn(message);
+
+                MessageBox.Show(message, "Fout", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                return;
+            }
+
+            if (referenceLineMetas.Any(rlm => String.IsNullOrEmpty(rlm.AssessmentSectionId)))
+            {
+                var message = new FileReaderErrorMessageBuilder(shapeFilePath)
+                    .Build("De trajectid's zijn niet allemaal ingevuld.");
+                log.Warn(message);
+
+                MessageBox.Show(message, "Fout", MessageBoxButtons.OK, MessageBoxIcon.Error);
+            }
+        }
     }
 }
\ No newline at end of file
Index: Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLinesMetaReader.cs
===================================================================
diff -u -r8e91f29f35b5f93ea1d9dfc7dcd79edfdd1b4e53 -r7d38bc43c1be859f9a410ed99c6dacb2a6f58126
--- Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLinesMetaReader.cs	(.../ReferenceLinesMetaReader.cs)	(revision 8e91f29f35b5f93ea1d9dfc7dcd79edfdd1b4e53)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLinesMetaReader.cs	(.../ReferenceLinesMetaReader.cs)	(revision 7d38bc43c1be859f9a410ed99c6dacb2a6f58126)
@@ -203,12 +203,7 @@
 
         private static string GetAssessmentSectionId(MapFeature lineFeature)
         {
-            var referenceLineId = Convert.ToString(lineFeature.MetaData[assessmentsectionIdAttributeKey]);
-            if (String.IsNullOrEmpty(referenceLineId))
-            {
-                throw new CriticalFileReadException(RingtoetsCommonIOResources.ReferenceLinesMetaReader_TrajectId_is_empty);
-            }
-            return referenceLineId;
+            return Convert.ToString(lineFeature.MetaData[assessmentsectionIdAttributeKey]);
         }
 
         private static int? GetSignalingValueAttributeKey(MapFeature lineFeature)
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/ReferenceLineMetaImporterTest.cs
===================================================================
diff -u -re3f0e0861e4d1f5faa32280e837777e8755b67d6 -r7d38bc43c1be859f9a410ed99c6dacb2a6f58126
--- Ringtoets/Common/test/Ringtoets.Common.IO.Test/ReferenceLineMetaImporterTest.cs	(.../ReferenceLineMetaImporterTest.cs)	(revision e3f0e0861e4d1f5faa32280e837777e8755b67d6)
+++ Ringtoets/Common/test/Ringtoets.Common.IO.Test/ReferenceLineMetaImporterTest.cs	(.../ReferenceLineMetaImporterTest.cs)	(revision 7d38bc43c1be859f9a410ed99c6dacb2a6f58126)
@@ -25,6 +25,7 @@
 using System.Linq;
 using Core.Common.IO.Exceptions;
 using Core.Common.TestUtil;
+using NUnit.Extensions.Forms;
 using NUnit.Framework;
 using Rhino.Mocks;
 using Ringtoets.Common.Data.AssessmentSection;
@@ -33,7 +34,7 @@
 namespace Ringtoets.Common.IO.Test
 {
     [TestFixture]
-    public class ReferenceLineMetaImporterTest
+    public class ReferenceLineMetaImporterTest : NUnitFormsAssertTest
     {
         private readonly string testDataPath = TestHelper.GetTestDataPath(TestDataPath.Ringtoets.Common.IO, "ReferenceLineMetaImporter");
 
@@ -197,5 +198,26 @@
             Assert.AreEqual(validReferenceId, assessmentSectionMock.Id);
             mockRepository.VerifyAll();
         }
+
+        [Test]
+        public void Constructor_FileWithNonUniqueTrajectIds_ThrowsException()
+        {
+            // Setup
+            string pathToFolder = Path.Combine(testDataPath, "NonUniqueTrajectIds");
+
+            // Call
+            Action call = () => new ReferenceLineMetaImporter(pathToFolder);
+
+            DialogBoxHandler = (name, wnd) =>
+            {
+                var messageBoxTester = new MessageBoxTester(wnd);
+                messageBoxTester.ClickOk();
+            };
+
+            // Assert
+            var shapeFile = Path.Combine(pathToFolder, "NonUniqueTrajectIds.shp");
+            var expectedMessage = string.Format("Fout bij het lezen van bestand '{0}': De trajectid's niet uniek.", shapeFile);
+            TestHelper.AssertLogMessageIsGenerated(call, expectedMessage);
+        }
     }
 }
\ No newline at end of file
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/ReferenceLinesMetaReaderTest.cs
===================================================================
diff -u -re3f0e0861e4d1f5faa32280e837777e8755b67d6 -r7d38bc43c1be859f9a410ed99c6dacb2a6f58126
--- Ringtoets/Common/test/Ringtoets.Common.IO.Test/ReferenceLinesMetaReaderTest.cs	(.../ReferenceLinesMetaReaderTest.cs)	(revision e3f0e0861e4d1f5faa32280e837777e8755b67d6)
+++ Ringtoets/Common/test/Ringtoets.Common.IO.Test/ReferenceLinesMetaReaderTest.cs	(.../ReferenceLinesMetaReaderTest.cs)	(revision 7d38bc43c1be859f9a410ed99c6dacb2a6f58126)
@@ -235,20 +235,18 @@
         }
 
         [Test]
-        public void ReadReferenceLinesMeta_EmptyTrackId_ThrowCriticalFileReadException()
+        public void ReadReferenceLinesMeta_EmptyTrackId_ReturnsElement()
         {
             // Setup
             string validFilePath = Path.Combine(testDataPath, "NBPW_EmptyTrackId.shp");
 
             using (var reader = new ReferenceLinesMetaReader(validFilePath))
             {
                 // Call
-                TestDelegate call = () => reader.ReadReferenceLinesMeta();
+                ReferenceLineMeta referenceLineMeta = reader.ReadReferenceLinesMeta();
 
                 // Assert
-                var message = Assert.Throws<CriticalFileReadException>(call).Message;
-                var expectedMessage = "Het bestand bevat geen waarde voor 'TrackID'.";
-                Assert.AreEqual(expectedMessage, message);
+                Assert.AreEqual(string.Empty,referenceLineMeta.AssessmentSectionId);
             }
         }
 
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ReferenceLineMetaImporter/NonUniqueTrajectIds/NonUniqueTrajectIds.dbf
===================================================================
diff -u
Binary files differ
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ReferenceLineMetaImporter/NonUniqueTrajectIds/NonUniqueTrajectIds.prj
===================================================================
diff -u
--- Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ReferenceLineMetaImporter/NonUniqueTrajectIds/NonUniqueTrajectIds.prj	(revision 0)
+++ Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ReferenceLineMetaImporter/NonUniqueTrajectIds/NonUniqueTrajectIds.prj	(revision 7d38bc43c1be859f9a410ed99c6dacb2a6f58126)
@@ -0,0 +1 @@
+PROJCS["Amersfoort_RD_New",GEOGCS["GCS_Amersfoort",DATUM["D_Amersfoort",SPHEROID["Bessel_1841",6377397.155,299.1528128]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Double_Stereographic"],PARAMETER["latitude_of_origin",52.15616055555555],PARAMETER["central_meridian",5.38763888888889],PARAMETER["scale_factor",0.9999079],PARAMETER["false_easting",155000],PARAMETER["false_northing",463000],UNIT["Meter",1]]
\ No newline at end of file
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ReferenceLineMetaImporter/NonUniqueTrajectIds/NonUniqueTrajectIds.qpj
===================================================================
diff -u
--- Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ReferenceLineMetaImporter/NonUniqueTrajectIds/NonUniqueTrajectIds.qpj	(revision 0)
+++ Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ReferenceLineMetaImporter/NonUniqueTrajectIds/NonUniqueTrajectIds.qpj	(revision 7d38bc43c1be859f9a410ed99c6dacb2a6f58126)
@@ -0,0 +1 @@
+PROJCS["Amersfoort / RD New",GEOGCS["Amersfoort",DATUM["Amersfoort",SPHEROID["Bessel 1841",6377397.155,299.1528128,AUTHORITY["EPSG","7004"]],TOWGS84[565.4171,50.3319,465.5524,-0.398957388243134,0.343987817378283,-1.87740163998045,4.0725],AUTHORITY["EPSG","6289"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4289"]],PROJECTION["Oblique_Stereographic"],PARAMETER["latitude_of_origin",52.15616055555555],PARAMETER["central_meridian",5.38763888888889],PARAMETER["scale_factor",0.9999079],PARAMETER["false_easting",155000],PARAMETER["false_northing",463000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["X",EAST],AXIS["Y",NORTH],AUTHORITY["EPSG","28992"]]
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ReferenceLineMetaImporter/NonUniqueTrajectIds/NonUniqueTrajectIds.shp
===================================================================
diff -u
Binary files differ
Index: Ringtoets/Common/test/Ringtoets.Common.IO.Test/test-data/ReferenceLineMetaImporter/NonUniqueTrajectIds/NonUniqueTrajectIds.shx
===================================================================
diff -u
Binary files differ