diff --git a/src/viewport_kdtree.h b/src/viewport_kdtree.h
new file mode 100644
--- /dev/null
+++ b/src/viewport_kdtree.h
@@ -0,0 +1,83 @@
+/*
+* This file is part of OpenTTD.
+* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+* OpenTTD 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 General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/** @file town_kdtree.h Declarations for accessing the k-d tree of towns */
+
+#ifndef VIEWPORT_KDTREE_H
+#define VIEWPORT_KDTREE_H
+
+#include "core/kdtree.hpp"
+#include "viewport_type.h"
+#include "station_base.h"
+#include "town_type.h"
+#include "signs_base.h"
+
+struct ViewportSignKdtreeItem {
+	enum ItemType : uint16 {
+		VKI_STATION,
+		VKI_WAYPOINT,
+		VKI_TOWN,
+		VKI_SIGN,
+	};
+	ItemType type;
+	union {
+		StationID station;
+		TownID town;
+		SignID sign;
+	} id;
+	int32 center;
+	int32 top;
+
+	bool operator== (const ViewportSignKdtreeItem &other) const
+	{
+		if (this->type != other.type) return false;
+		switch (this->type) {
+			case VKI_STATION:
+			case VKI_WAYPOINT:
+				return this->id.station == other.id.station;
+			case VKI_TOWN:
+				return this->id.town == other.id.town;
+			case VKI_SIGN:
+				return this->id.sign == other.id.sign;
+			default:
+				NOT_REACHED();
+		}
+	}
+
+	bool operator< (const ViewportSignKdtreeItem &other) const
+	{
+		if (this->type != other.type) return this->type < other.type;
+		switch (this->type) {
+			case VKI_STATION:
+			case VKI_WAYPOINT:
+				return this->id.station < other.id.station;
+			case VKI_TOWN:
+				return this->id.town < other.id.town;
+			case VKI_SIGN:
+				return this->id.sign < other.id.sign;
+			default:
+				NOT_REACHED();
+		}
+	}
+
+	static ViewportSignKdtreeItem MakeStation(StationID id);
+	static ViewportSignKdtreeItem MakeWaypoint(StationID id);
+	static ViewportSignKdtreeItem MakeTown(TownID id);
+	static ViewportSignKdtreeItem MakeSign(SignID id);
+};
+
+inline int32 Kdtree_ViewportSignXYFunc(const ViewportSignKdtreeItem &item, int dim)
+{
+	return (dim == 0) ? item.center : item.top;
+}
+
+typedef Kdtree<ViewportSignKdtreeItem, decltype(&Kdtree_ViewportSignXYFunc), int32, int32> ViewportSignKdtree;
+extern ViewportSignKdtree _viewport_sign_kdtree;
+
+void RebuildViewportKdtree();
+
+#endif