diff --git a/mapbuilder/utils/ecl.py b/mapbuilder/utils/ecl.py
index 9f07513..3e70a88 100644
--- a/mapbuilder/utils/ecl.py
+++ b/mapbuilder/utils/ecl.py
@@ -1,5 +1,5 @@
-from mapbuilder.utils.geo import Brg, Fix, back_bearing
 
+from mapbuilder.utils.geo import Brg, Fix, back_bearing
 
 def extrapolate_rwy(rwy_info, count: int, dist: float = 1) -> list[Fix]:
     """Extrapolates count points from the runway threshold, each spaced dist nautical miles apart
@@ -33,16 +33,21 @@ def draw_loc_tick(rwy_info, gap: float, length: float):
     return str(Fix(rwy_info["loc"]).move_to(gap, brg).line_to(length, brg))
 
 
-def draw_marker_ticks(rwy_info, at: list, gap: float, length: float):
+def draw_marker_ticks(rwy_info, at: list, gap: float, length: float, symmetry: str = "B"):
     lines = []
     brg = Brg(rwy_info["bearing"]).invert()
     tick_brg = brg + 90
     for dist in at:
         base = Fix(rwy_info["thr"]).move_to(dist, brg)
 
-        lines.extend((
-            str(base.move_to(gap, tick_brg).line_to(length, tick_brg)),
-            str(base.move_to(-gap, tick_brg).line_to(-length, tick_brg)),
-        ))
+        if symmetry == "B":
+            lines.extend((str(base.move_to(gap, tick_brg).line_to(length, tick_brg)),
+                        str(base.move_to(-gap, tick_brg).line_to(-length, tick_brg))))
+        elif symmetry == "L":
+            lines.append(str(base.move_to(gap, tick_brg).line_to(length, tick_brg)))
+        elif symmetry == "R":
+            lines.append(str(base.move_to(-gap, tick_brg).line_to(-length, tick_brg)))
+        else:
+            raise ValueError(f"Unknown argument {symmetry}")
 
     return "\n".join(lines)