diff --git a/gtfsdb/model/db.py b/gtfsdb/model/db.py
index d96f0ed..fc17f14 100644
--- a/gtfsdb/model/db.py
+++ b/gtfsdb/model/db.py
@@ -7,6 +7,12 @@
 class Database(object):
 
     def __init__(self, **kwargs):
+        '''
+        keyword arguments:
+            url: SQLAlchemy database url
+            schema: database schema name
+            is_geospatial: if database supports geo functions
+        '''
         self.url = kwargs.get('url', config.DEFAULT_DATABASE_URL)
         self.schema = kwargs.get('schema', config.DEFAULT_SCHEMA)
         self.is_geospatial = kwargs.get('is_geospatial',
@@ -60,6 +66,16 @@ def schema(self, val):
         for cls in self.classes:
             cls.__table__.schema = val
 
+    @property
+    def sorted_classes(self):
+        classes = []
+        for t in self.metadata.sorted_tables:
+            cls = next((c for c in self.classes
+                        if c.__table__ == t), None)
+            if cls:
+                classes.append(cls)
+        return classes
+
     @property
     def url(self):
         return self._url
diff --git a/gtfsdb/model/gtfs.py b/gtfsdb/model/gtfs.py
index c872a33..15fab23 100644
--- a/gtfsdb/model/gtfs.py
+++ b/gtfsdb/model/gtfs.py
@@ -27,7 +27,7 @@ def load(self, db, **kwargs):
             batch_size=kwargs.get('batch_size', config.DEFAULT_BATCH_SIZE),
             gtfs_directory=gtfs_directory,
         )
-        for cls in db.classes:
+        for cls in db.sorted_classes:
             cls.load(db, **load_kwargs)
         shutil.rmtree(gtfs_directory)