Index: Core/Common/src/Core.Common.Base/Core.Common.Base.csproj
===================================================================
diff -u -r07f3d67fe9512b3c8303ff09398b0a234900d546 -r2fd427d95bfd8c000da089fedcf7b2fe2ca592e2
--- Core/Common/src/Core.Common.Base/Core.Common.Base.csproj	(.../Core.Common.Base.csproj)	(revision 07f3d67fe9512b3c8303ff09398b0a234900d546)
+++ Core/Common/src/Core.Common.Base/Core.Common.Base.csproj	(.../Core.Common.Base.csproj)	(revision 2fd427d95bfd8c000da089fedcf7b2fe2ca592e2)
@@ -102,6 +102,7 @@
     <Compile Include="Geometry\Point3DCollectionExtensions.cs" />
     <Compile Include="Geometry\Point3DExtensions.cs" />
     <Compile Include="Geometry\Segment2D.cs" />
+    <Compile Include="Geometry\Segment2DCollectionExtensions.cs" />
     <Compile Include="Geometry\Segment2DIntersectSegment2DResult.cs" />
     <Compile Include="IO\CriticalFileReadException.cs" />
     <Compile Include="IO\FileImporterBase.cs" />
Index: Core/Common/src/Core.Common.Base/Geometry/Segment2DCollectionExtensions.cs
===================================================================
diff -u
--- Core/Common/src/Core.Common.Base/Geometry/Segment2DCollectionExtensions.cs	(revision 0)
+++ Core/Common/src/Core.Common.Base/Geometry/Segment2DCollectionExtensions.cs	(revision 2fd427d95bfd8c000da089fedcf7b2fe2ca592e2)
@@ -0,0 +1,75 @@
+// Copyright (C) Stichting Deltares 2017. All rights reserved.
+//
+// This file is part of Ringtoets.
+//
+// Ringtoets is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Core.Common.Base.Geometry
+{
+    /// <summary>
+    /// Extension methods for collections of <see cref="Segment2D"/>.
+    /// </summary>
+    public static class Segment2DCollectionExtensions
+    {
+        /// <summary>
+        /// Interpolates the segments on <paramref name="x"/>.
+        /// </summary>
+        /// <param name="segments">The segments to interpolate on.</param>
+        /// <param name="x">The x value to use for interpolation.</param>
+        /// <returns>The interpolated y value of the segment that is closest to <paramref name="x"/> 
+        /// or <see cref="double.NaN"/> when no interpolation was found.</returns>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="segments"/> is <c>null</c>.</exception>
+        public static double Interpolate(this IEnumerable<Segment2D> segments, double x)
+        {
+            if (segments == null)
+            {
+                throw new ArgumentNullException(nameof(segments));
+            }
+
+            Segment2D segment = segments.LastOrDefault(s => s.FirstPoint.X <= x) ?? segments.First();
+
+            return Interpolate(segment, x);
+        }
+
+        /// <summary>
+        /// Interpolates the segment on <paramref name="x"/>.
+        /// </summary>
+        /// <param name="segment">The segment to interpolate on.</param>
+        /// <param name="x">The x value to use for interpolation.</param>
+        /// <returns>The interpolated y value of the <paramref name="segment"/> or 
+        /// <see cref="double.NaN"/> when no interpolation was found.</returns>
+        private static double Interpolate(Segment2D segment, double x)
+        {
+            double differenceInX = segment.SecondPoint.X - segment.FirstPoint.X;
+            if (Math.Abs(differenceInX) < 1e-6)
+            {
+                return double.NaN;
+            }
+
+            double m = (segment.SecondPoint.Y - segment.FirstPoint.Y) / differenceInX;
+
+            double b = segment.FirstPoint.Y - (m * segment.FirstPoint.X);
+
+            return m * x + b;
+        }
+    }
+}
\ No newline at end of file
Index: Core/Common/test/Core.Common.Base.Test/Core.Common.Base.Test.csproj
===================================================================
diff -u -r354316fca628a0f9dcdee5ff156ae4d87e662677 -r2fd427d95bfd8c000da089fedcf7b2fe2ca592e2
--- Core/Common/test/Core.Common.Base.Test/Core.Common.Base.Test.csproj	(.../Core.Common.Base.Test.csproj)	(revision 354316fca628a0f9dcdee5ff156ae4d87e662677)
+++ Core/Common/test/Core.Common.Base.Test/Core.Common.Base.Test.csproj	(.../Core.Common.Base.Test.csproj)	(revision 2fd427d95bfd8c000da089fedcf7b2fe2ca592e2)
@@ -93,6 +93,7 @@
     <Compile Include="Geometry\Point3DCollectionExtensionsTest.cs" />
     <Compile Include="Geometry\Point3DExtensionsTest.cs" />
     <Compile Include="Geometry\Point3DTest.cs" />
+    <Compile Include="Geometry\Segment2DCollectionExtensionsTest.cs" />
     <Compile Include="Geometry\Segment2DIntersectSegment2DResultTest.cs" />
     <Compile Include="Geometry\Segment2DTest.cs" />
     <Compile Include="IO\CriticalFileReadExceptionTest.cs" />
Index: Core/Common/test/Core.Common.Base.Test/Geometry/Segment2DCollectionExtensionsTest.cs
===================================================================
diff -u
--- Core/Common/test/Core.Common.Base.Test/Geometry/Segment2DCollectionExtensionsTest.cs	(revision 0)
+++ Core/Common/test/Core.Common.Base.Test/Geometry/Segment2DCollectionExtensionsTest.cs	(revision 2fd427d95bfd8c000da089fedcf7b2fe2ca592e2)
@@ -0,0 +1,147 @@
+// Copyright (C) Stichting Deltares 2017. All rights reserved.
+//
+// This file is part of Ringtoets.
+//
+// Ringtoets is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using Core.Common.Base.Geometry;
+using NUnit.Framework;
+
+namespace Core.Common.Base.Test.Geometry
+{
+    [TestFixture]
+    public class Segment2DCollectionExtensionsTest
+    {
+        [Test]
+        public void Interpolate_SegmentsNull_ThrowsArgumentNullException()
+        {
+            // Call
+            TestDelegate test = () => ((IEnumerable<Segment2D>) null).Interpolate(0);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(test);
+            Assert.AreEqual("segments", exception.ParamName);
+        }
+
+        [Test]
+        [TestCaseSource(nameof(ValidInterpolation))]
+        public void Interpolate_ValidArguments_ReturnsExpectedResult(IEnumerable<Segment2D> segments,
+                                                                     double interpolateOnX,
+                                                                     double expectedY)
+        {
+            // Call
+            double actualY = segments.Interpolate(interpolateOnX);
+
+            // Assert
+            Assert.AreEqual(expectedY, actualY);
+        }
+
+        [Test]
+        [TestCaseSource(nameof(InvalidInterpolation))]
+        public void Interpolate_InvalidArguments_ReturnsNaN(IEnumerable<Segment2D> segments,
+                                                            double interpolateOnX)
+        {
+            // Call
+            double actualY = segments.Interpolate(interpolateOnX);
+
+            // Assert
+            Assert.IsNaN(actualY);
+        }
+
+        private static IEnumerable<TestCaseData> ValidInterpolation()
+        {
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(-1000, 0), new Point2D(1, 1)),
+                new Segment2D(new Point2D(1, 1), new Point2D(10, 10)),
+                new Segment2D(new Point2D(100, 100), new Point2D(1000, 10))
+            }, 20, 20).SetName("Slope = 1, b = 0 with other segments");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(0, 10), new Point2D(10, 100))
+            }, 0, 10).SetName("Same as first point that passed through origin");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(0, 10), new Point2D(10, 100))
+            }, -10, -80).SetName("Left of first point");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(1, 10), new Point2D(10, 100))
+            }, 1, 10).SetName("Same as first point");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(1, 10), new Point2D(10, 100))
+            }, 10, 100).SetName("Same as second point");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(0, 10), new Point2D(10, 10)),
+                new Segment2D(new Point2D(10, 10), new Point2D(20, 100))
+            }, 30, 190).SetName("Right of last point");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(1, 1), new Point2D(10, 10))
+            }, 5, 5).SetName("Slope = 1, b = 0");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(0, 0), new Point2D(10, 1000))
+            }, 5, 500).SetName("Slope = 100, b = 0");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(0, 0), new Point2D(-5, -9))
+            }, 5, (9.0 / 5.0) * 5).SetName("Slope = 9/5, b = 0");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(5, 2), new Point2D(90, 3))
+            }, 50, ((1 / 85.0) * 50) + (33 / 17.0)).SetName("Slope = 1/85, b = 33/17");
+        }
+
+        private static IEnumerable<TestCaseData> InvalidInterpolation()
+        {
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(0, 10), new Point2D(0, 10))
+            }, 0).SetName("Vertical line");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(0, 0), new Point2D(double.PositiveInfinity, double.PositiveInfinity))
+            }, 20).SetName("PositiveInfinity");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(0, 0), new Point2D(double.NegativeInfinity, double.NegativeInfinity))
+            }, 20).SetName("NegativeInfinity");
+
+            yield return new TestCaseData(new[]
+            {
+                new Segment2D(new Point2D(0, 0), new Point2D(double.NaN, double.NaN))
+            }, 20).SetName("NaN");
+        }
+    }
+}
\ No newline at end of file