diff --git a/include/boost/geometry/algorithms/detail/group_dim.hpp b/include/boost/geometry/algorithms/detail/group_dim.hpp
new file mode 100644
index 000000000..a5c445b88
--- /dev/null
+++ b/include/boost/geometry/algorithms/detail/group_dim.hpp
@@ -0,0 +1,79 @@
+// Boost.Geometry (aka GGL, Generic Geometry Library)
+
+// Copyright (c) 2014 Oracle and/or its affiliates.
+
+// Use, modification and distribution is subject to the Boost Software License,
+// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
+
+#ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_GROUP_DIM_HPP
+#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_GROUP_DIM_HPP
+
+#include <boost/type_traits/is_base_of.hpp>
+
+#include <boost/geometry/core/tag.hpp>
+
+namespace boost { namespace geometry {
+
+#ifndef DOXYGEN_NO_DETAIL
+namespace detail {
+
+template <typename Geometry,
+          typename Tag = typename geometry::tag<Geometry>::type,
+          bool IsPoint = boost::is_base_of<pointlike_tag, Tag>::value,
+          bool IsLinear = boost::is_base_of<linear_tag, Tag>::value,
+          bool IsAreal = boost::is_base_of<areal_tag, Tag>::value>
+struct group_tag
+    : not_implemented<Tag>
+{};
+
+template <typename Geometry, typename Tag>
+struct group_tag<Geometry, Tag, true, false, false>
+{
+    typedef pointlike_tag type;
+};
+
+template <typename Geometry, typename Tag>
+struct group_tag<Geometry, Tag, false, true, false>
+{
+    typedef linear_tag type;
+};
+
+template <typename Geometry, typename Tag>
+struct group_tag<Geometry, Tag, false, false, true>
+{
+    typedef areal_tag type;
+};
+
+template <typename Geometry,
+          typename GroupTag = typename group_tag<Geometry>::type>
+struct group_dim
+    : not_implemented<GroupTag>
+{};
+
+template <typename Geometry>
+struct group_dim<Geometry, pointlike_tag>
+{
+    static const int value = 0;
+};
+
+template <typename Geometry>
+struct group_dim<Geometry, linear_tag>
+{
+    static const int value = 1;
+};
+
+template <typename Geometry>
+struct group_dim<Geometry, areal_tag>
+{
+    static const int value = 2;
+};
+
+} // namespace detail
+#endif // DOXYGEN_NO_DETAIL
+
+}} // namespace boost::geometry
+
+#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_GROUP_DIM_HPP
diff --git a/include/boost/geometry/algorithms/detail/overlay/get_turns.hpp b/include/boost/geometry/algorithms/detail/overlay/get_turns.hpp
index c84057f3f..aa615e154 100644
--- a/include/boost/geometry/algorithms/detail/overlay/get_turns.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/get_turns.hpp
@@ -735,71 +735,6 @@ struct get_turns_polygon_cs
     }
 };
 
-}} // namespace detail::get_turns
-#endif // DOXYGEN_NO_DETAIL
-
-// TODO: move group_tag and group_dim to separate file
-
-#ifndef DOXYGEN_NO_DETAIL
-namespace detail {
-
-template <typename Geometry,
-          typename Tag = typename geometry::tag<Geometry>::type,
-          bool IsPoint = boost::is_base_of<pointlike_tag, Tag>::value,
-          bool IsLinear = boost::is_base_of<linear_tag, Tag>::value,
-          bool IsAreal = boost::is_base_of<areal_tag, Tag>::value>
-struct group_tag
-    : not_implemented<Tag>
-{};
-
-template <typename Geometry, typename Tag>
-struct group_tag<Geometry, Tag, true, false, false>
-{
-    typedef pointlike_tag type;
-};
-
-template <typename Geometry, typename Tag>
-struct group_tag<Geometry, Tag, false, true, false>
-{
-    typedef linear_tag type;
-};
-
-template <typename Geometry, typename Tag>
-struct group_tag<Geometry, Tag, false, false, true>
-{
-    typedef areal_tag type;
-};
-
-template <typename Geometry,
-          typename GroupTag = typename group_tag<Geometry>::type>
-struct group_dim
-    : not_implemented<GroupTag>
-{};
-
-template <typename Geometry>
-struct group_dim<Geometry, pointlike_tag>
-{
-    static const int value = 0;
-};
-
-template <typename Geometry>
-struct group_dim<Geometry, linear_tag>
-{
-    static const int value = 1;
-};
-
-template <typename Geometry>
-struct group_dim<Geometry, areal_tag>
-{
-    static const int value = 2;
-};
-
-} // namespace detail
-#endif // DOXYGEN_NO_DETAIL
-
-#ifndef DOXYGEN_NO_DETAIL
-namespace detail { namespace get_turns {
-
 // GET_TURN_INFO_TYPE
 
 template <typename Geometry1, typename Geometry2, typename AssignPolicy,
diff --git a/include/boost/geometry/algorithms/detail/relate/linear_areal.hpp b/include/boost/geometry/algorithms/detail/relate/linear_areal.hpp
index d27b826e2..8fc9acf5f 100644
--- a/include/boost/geometry/algorithms/detail/relate/linear_areal.hpp
+++ b/include/boost/geometry/algorithms/detail/relate/linear_areal.hpp
@@ -14,6 +14,7 @@
 #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_RELATE_LINEAR_AREAL_HPP
 #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_RELATE_LINEAR_AREAL_HPP
 
+#include <boost/geometry/algorithms/detail/group_dim.hpp>
 #include <boost/geometry/algorithms/detail/sub_geometry.hpp>
 #include <boost/geometry/algorithms/detail/range_helpers.hpp>