diff --git a/src/Mod/FreeCADExchange/RoutingNetwork.py b/src/Mod/FreeCADExchange/RoutingNetwork.py
index 5ac5f4a..022df06 100644
--- a/src/Mod/FreeCADExchange/RoutingNetwork.py
+++ b/src/Mod/FreeCADExchange/RoutingNetwork.py
@@ -2278,6 +2278,19 @@ def _segment_usage_key(carrier, from_key, to_key):
     )
 
 
+def _carrier_capacity(carrier):
+    if carrier is None:
+        return 1
+    for property_name in ("QetRouteCarrierCapacity", "QetWireCapacity"):
+        try:
+            value = int(float(getattr(carrier, property_name, 0) or 0))
+        except Exception:
+            value = 0
+        if value > 0:
+            return value
+    return 1
+
+
 def shortest_path_with_carriers(
     network,
     start_key,
@@ -2362,7 +2375,9 @@ def shortest_path_with_carriers(
             usage_cost = 0.0
             if segment_usage_costs:
                 usage_count = float(segment_usage_costs.get(_segment_usage_key(carrier, key, next_key), 0.0) or 0.0)
-                usage_cost = usage_count * float(segment_reuse_penalty or 0.0)
+                capacity = float(_carrier_capacity(carrier))
+                excess_usage = max(usage_count - capacity + 1.0, 0.0)
+                usage_cost = excess_usage * float(segment_reuse_penalty or 0.0)
             next_state = (next_key, direction)
             next_cost = (
                 cost
diff --git a/tests/python/freecad_exchange_auto_routing_test.py b/tests/python/freecad_exchange_auto_routing_test.py
index bb3f2d4..953ce76 100644
--- a/tests/python/freecad_exchange_auto_routing_test.py
+++ b/tests/python/freecad_exchange_auto_routing_test.py
@@ -2035,6 +2035,79 @@ class AutoRoutingTest(unittest.TestCase):
         self.assertIn("Alternate Duct", second_labels)
         self.assertNotIn("Direct Duct", second_labels)
 
+    def test_route_eplan_connections_respects_route_segment_capacity_before_detouring(self):
+        _install_fake_freecad()
+        terminal_objects, _wiring_objects, routing_network, auto_routing = _reload_modules()
+        app = sys.modules["FreeCAD"]
+        doc = FakeDocument()
+        terminal_objects.ensure_root_group(doc, "project-1")
+        _terminal(doc, terminal_objects, "TerminalStartA", "terminal-start-a", app.Vector(0, 0, 0))
+        _terminal(doc, terminal_objects, "TerminalEndA", "terminal-end-a", app.Vector(100, 0, 0))
+        _terminal(doc, terminal_objects, "TerminalStartB", "terminal-start-b", app.Vector(0, 0, 0))
+        _terminal(doc, terminal_objects, "TerminalEndB", "terminal-end-b", app.Vector(100, 0, 0))
+        _terminal(doc, terminal_objects, "TerminalStartC", "terminal-start-c", app.Vector(0, 0, 0))
+        _terminal(doc, terminal_objects, "TerminalEndC", "terminal-end-c", app.Vector(100, 0, 0))
+        direct = routing_network.create_route_carrier(
+            doc,
+            [app.Vector(0, 0, 20), app.Vector(100, 0, 20)],
+            label="Direct Duct",
+            project_uuid="project-1",
+            kind="WireDuct",
+        )
+        direct.QetRouteCarrierCapacity = 2
+        routing_network.create_route_carrier(
+            doc,
+            [app.Vector(0, 0, 20), app.Vector(0, 40, 20)],
+            label="Left Bridge",
+            project_uuid="project-1",
+            kind="WireDuct",
+        )
+        routing_network.create_route_carrier(
+            doc,
+            [app.Vector(0, 40, 20), app.Vector(100, 40, 20)],
+            label="Alternate Duct",
+            project_uuid="project-1",
+            kind="WireDuct",
+        )
+        routing_network.create_route_carrier(
+            doc,
+            [app.Vector(100, 40, 20), app.Vector(100, 0, 20)],
+            label="Right Bridge",
+            project_uuid="project-1",
+            kind="WireDuct",
+        )
+        payload = {
+            "project_uuid": "project-1",
+            "wires": [
+                {
+                    "wire_id": "wire-a",
+                    "start_terminal_uuid": "terminal-start-a",
+                    "end_terminal_uuid": "terminal-end-a",
+                },
+                {
+                    "wire_id": "wire-b",
+                    "start_terminal_uuid": "terminal-start-b",
+                    "end_terminal_uuid": "terminal-end-b",
+                },
+                {
+                    "wire_id": "wire-c",
+                    "start_terminal_uuid": "terminal-start-c",
+                    "end_terminal_uuid": "terminal-end-c",
+                },
+            ],
+        }
+
+        report = auto_routing.route_eplan_connections_from_payload(doc, payload)
+
+        route_labels = [
+            [segment["carrier"]["label"] for segment in route["route_track"]["segments"]]
+            for route in report["routes"]
+        ]
+        self.assertIn("Direct Duct", route_labels[0])
+        self.assertIn("Direct Duct", route_labels[1])
+        self.assertIn("Alternate Duct", route_labels[2])
+        self.assertNotIn("Direct Duct", route_labels[2])
+
     def test_route_eplan_connections_prefers_unused_segments_occupied_by_existing_wires(self):
         _install_fake_freecad()
         terminal_objects, _wiring_objects, routing_network, auto_routing = _reload_modules()