diff --git a/stairsplus/common.lua b/stairsplus/common.lua
index 5534d8f..98b30a0 100644
--- a/stairsplus/common.lua
+++ b/stairsplus/common.lua
@@ -166,6 +166,7 @@ stairsplus.register_single = function(category, alternate, info, modname, subnam
 		def.description = desc_base
 		if category == "slope" then
 			def.drawtype = "mesh"
+			def.group.not_blocking_trains = 1
 		elseif category == "stair" and alternate == "" then
 			def.groups.stair = 1
 		end