diff -r 07efd7789987 -r 5de2bbd26163 src/ai/trolly/trolly.cpp
--- a/src/ai/trolly/trolly.cpp	Fri Oct 19 21:14:38 2007 +0000
+++ b/src/ai/trolly/trolly.cpp	Fri Oct 19 22:46:55 2007 +0000
@@ -1111,7 +1111,7 @@
 	}
 
 	// There is a bus on the tile we want to build road on... idle till he is gone! (BAD PERSON! :p)
-	if (!EnsureNoVehicle(p->ainew.depot_tile + TileOffsByDiagDir(p->ainew.depot_direction)))
+	if (!EnsureNoVehicleOnGround(p->ainew.depot_tile + TileOffsByDiagDir(p->ainew.depot_direction)))
 		return;
 
 	res = AiNew_Build_Depot(p, p->ainew.depot_tile, p->ainew.depot_direction, DC_EXEC);