diff --git a/application/src/main/java/org/opentripplanner/apis/transmodel/mapping/RelativeDirectionMapper.java b/application/src/main/java/org/opentripplanner/apis/transmodel/mapping/RelativeDirectionMapper.java
new file mode 100644
index 00000000000..3228cb914df
--- /dev/null
+++ b/application/src/main/java/org/opentripplanner/apis/transmodel/mapping/RelativeDirectionMapper.java
@@ -0,0 +1,33 @@
+package org.opentripplanner.apis.transmodel.mapping;
+
+import org.opentripplanner.model.plan.RelativeDirection;
+
+/**
+ * This mapper makes sure that only those values are returned which have a mapping in the Transmodel API,
+ * as we don't really want to return all of them.
+ */
+public class RelativeDirectionMapper {
+
+  public static RelativeDirection map(RelativeDirection relativeDirection) {
+    return switch (relativeDirection) {
+      case DEPART,
+        SLIGHTLY_LEFT,
+        HARD_LEFT,
+        LEFT,
+        CONTINUE,
+        SLIGHTLY_RIGHT,
+        RIGHT,
+        HARD_RIGHT,
+        CIRCLE_CLOCKWISE,
+        CIRCLE_COUNTERCLOCKWISE,
+        ELEVATOR,
+        UTURN_LEFT,
+        UTURN_RIGHT -> relativeDirection;
+      // for these the Transmodel API doesn't have a mapping. should it?
+      case ENTER_STATION,
+        EXIT_STATION,
+        ENTER_OR_EXIT_STATION,
+        FOLLOW_SIGNS -> RelativeDirection.CONTINUE;
+    };
+  }
+}
diff --git a/application/src/main/java/org/opentripplanner/apis/transmodel/model/plan/PathGuidanceType.java b/application/src/main/java/org/opentripplanner/apis/transmodel/model/plan/PathGuidanceType.java
index 86c8359c026..8840e8fedb8 100644
--- a/application/src/main/java/org/opentripplanner/apis/transmodel/model/plan/PathGuidanceType.java
+++ b/application/src/main/java/org/opentripplanner/apis/transmodel/model/plan/PathGuidanceType.java
@@ -5,6 +5,7 @@
 import graphql.schema.GraphQLList;
 import graphql.schema.GraphQLNonNull;
 import graphql.schema.GraphQLObjectType;
+import org.opentripplanner.apis.transmodel.mapping.RelativeDirectionMapper;
 import org.opentripplanner.apis.transmodel.model.EnumTypes;
 import org.opentripplanner.framework.graphql.GraphQLUtils;
 import org.opentripplanner.model.plan.WalkStep;
@@ -31,7 +32,9 @@ public static GraphQLObjectType create(GraphQLObjectType elevationStepType) {
           .name("relativeDirection")
           .description("The relative direction of this step.")
           .type(EnumTypes.RELATIVE_DIRECTION)
-          .dataFetcher(environment -> ((WalkStep) environment.getSource()).getRelativeDirection())
+          .dataFetcher(environment ->
+            RelativeDirectionMapper.map(((WalkStep) environment.getSource()).getRelativeDirection())
+          )
           .build()
       )
       .field(
diff --git a/application/src/test/java/org/opentripplanner/apis/transmodel/model/EnumTypesTest.java b/application/src/test/java/org/opentripplanner/apis/transmodel/model/EnumTypesTest.java
index 3d834fced58..9090cd1bdc5 100644
--- a/application/src/test/java/org/opentripplanner/apis/transmodel/model/EnumTypesTest.java
+++ b/application/src/test/java/org/opentripplanner/apis/transmodel/model/EnumTypesTest.java
@@ -1,14 +1,23 @@
 package org.opentripplanner.apis.transmodel.model;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.opentripplanner.apis.transmodel.model.EnumTypes.RELATIVE_DIRECTION;
 import static org.opentripplanner.apis.transmodel.model.EnumTypes.ROUTING_ERROR_CODE;
 import static org.opentripplanner.apis.transmodel.model.EnumTypes.map;
 
+import graphql.GraphQLContext;
 import java.util.EnumSet;
 import java.util.List;
+import java.util.Locale;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+import org.opentripplanner.apis.transmodel.mapping.RelativeDirectionMapper;
 import org.opentripplanner.framework.doc.DocumentedEnum;
+import org.opentripplanner.model.plan.RelativeDirection;
 import org.opentripplanner.routing.api.response.RoutingErrorCode;
 
 class EnumTypesTest {
@@ -75,6 +84,18 @@ void testMap() {
     assertEquals("DocumentedEnumMapping[apiName=iH, internal=Hi]", mapping.toString());
   }
 
+  @ParameterizedTest
+  @EnumSource(RelativeDirection.class)
+  void serializeRelativeDirection(RelativeDirection direction) {
+    var value = RELATIVE_DIRECTION.serialize(
+      RelativeDirectionMapper.map(direction),
+      GraphQLContext.getDefault(),
+      Locale.ENGLISH
+    );
+    assertInstanceOf(String.class, value);
+    assertNotNull(value);
+  }
+
   @Test
   void assertAllRoutingErrorCodesAreMapped() {
     var expected = EnumSet.allOf(RoutingErrorCode.class);