diff --git a/B05_wf2_Route/B05_wf2_Route_Router_Drainage.py b/B05_wf2_Route/B05_wf2_Route_Router_Drainage.py
index fabb361a..359fe649 100644
--- a/B05_wf2_Route/B05_wf2_Route_Router_Drainage.py
+++ b/B05_wf2_Route/B05_wf2_Route_Router_Drainage.py
@@ -123,7 +123,10 @@ async def _prepare(project_id: UUID) -> dict[str, Any] | JSONResponse:
                 content={"status": "error", "message": "확정된 경로가 없습니다."},
             )
         points = await get_route_points(connection, int(route["id"]))
-        epsg = await get_surface_crs_epsg(connection, project_id)
+        surface_model_id = route.get("surface_model_id")
+        epsg = await get_surface_crs_epsg(
+            connection, project_id, int(surface_model_id) if surface_model_id else 0
+        )
 
     vertices = build_route_vertices(points)
     if len(vertices) < 2:
@@ -132,7 +135,7 @@ async def _prepare(project_id: UUID) -> dict[str, Any] | JSONResponse:
             content={"status": "error", "message": "노선 좌표가 부족합니다."},
         )
 
-    source_crs = epsg or "EPSG:5186"
+    source_crs = f"EPSG:{epsg}" if epsg else "EPSG:5186"
     to_lonlat_transformer = Transformer.from_crs(source_crs, "EPSG:4326", always_xy=True)
     to_metric_transformer = Transformer.from_crs("EPSG:4326", source_crs, always_xy=True)