diff --git a/orm_importer/importer.py b/orm_importer/importer.py
index 1afc186..78c4c95 100644
--- a/orm_importer/importer.py
+++ b/orm_importer/importer.py
@@ -145,7 +145,9 @@ def _should_add_edge(self, node_a: model.Node, node_b: model.Node, path: list[in
         present_paths = self.paths[(node_a, node_b)] + self.paths[(node_b, node_a)]
         return path not in present_paths and reversed_path not in present_paths
 
-    def run(self, polygon, railway_option_types):
+    def run(self, polygon, railway_option_types: list[str] = None):
+        if railway_option_types is None:
+            railway_option_types = ["rail"]
         track_objects = self._get_track_objects(polygon, railway_option_types)
         self.graph = self._build_graph(track_objects)
 
diff --git a/tests/test_converter.py b/tests/test_converter.py
index 1d07a71..e40c8ec 100644
--- a/tests/test_converter.py
+++ b/tests/test_converter.py
@@ -20,4 +20,4 @@ def test_query_griebnitzsee(mock_converter):
 
     assert len(res.nodes) == 10
     assert len(res.edges) == 9
-    assert len(res.signals) == 9
+    assert len(res.signals) == 17