diff --git a/tests/test_raillabel_providerkit/validation/validate_rail_side/test_validate_rail_side.py b/tests/test_raillabel_providerkit/validation/validate_rail_side/test_validate_rail_side.py
index e46cff5..dc5b26f 100644
--- a/tests/test_raillabel_providerkit/validation/validate_rail_side/test_validate_rail_side.py
+++ b/tests/test_raillabel_providerkit/validation/validate_rail_side/test_validate_rail_side.py
@@ -6,19 +6,143 @@
 
 from raillabel_providerkit.validation.validate_rail_side.validate_rail_side import (
     validate_rail_side,
+    _count_rails_per_track_in_frame,
 )
 
 
-def test_validate_rail_side__no_errors(empty_scene, empty_frame):
-    scene = empty_scene
-    object = raillabel.format.Object(
-        uid="a1082ef9-555b-4b69-a888-7da531d8a2eb", name="track0001", type="track"
-    )
-    scene.objects[object.uid] = object
-    sensor = raillabel.format.Sensor(
+@pytest.fixture
+def example_camera_1() -> raillabel.format.Sensor:
+    return raillabel.format.Sensor(
         uid="rgb_center",
         type=raillabel.format.SensorType.CAMERA,
     )
+
+
+@pytest.fixture
+def example_camera_2() -> raillabel.format.Sensor:
+    return raillabel.format.Sensor(
+        uid="ir_center",
+        type=raillabel.format.SensorType.CAMERA,
+    )
+
+
+@pytest.fixture
+def example_track_1() -> raillabel.format.Object:
+    return raillabel.format.Object(
+        uid="a1082ef9-555b-4b69-a888-7da531d8a2eb", name="track0001", type="track"
+    )
+
+
+@pytest.fixture
+def example_track_2() -> raillabel.format.Object:
+    return raillabel.format.Object(
+        uid="6e92e7af-3bc8-4225-b538-16d19e3f8aa7", name="track0002", type="track"
+    )
+
+
+def test_count_rails_per_track_in_frame__empty(empty_frame):
+    frame = empty_frame
+    results = _count_rails_per_track_in_frame(frame)
+    assert len(results) == 0
+
+
+def test_count_rails_per_track_in_frame__many_rails_for_one_track(
+    empty_frame, example_camera_1, example_track_1
+):
+    frame = empty_frame
+    sensor = example_camera_1
+    object = example_track_1
+
+    LEFT_COUNT = 32
+    RIGHT_COUNT = 42
+
+    for i in range(LEFT_COUNT):
+        uid = f"test_left_{i}"
+        frame.annotations[uid] = raillabel.format.Poly2d(
+            uid=uid,
+            object=object,
+            sensor=sensor,
+            points=[
+                raillabel.format.Point2d(0, 0),
+                raillabel.format.Point2d(0, 1),
+            ],
+            closed=False,
+            attributes={"railSide": "leftRail"},
+        )
+
+    for i in range(RIGHT_COUNT):
+        uid = f"test_right_{i}"
+        frame.annotations[uid] = raillabel.format.Poly2d(
+            uid=uid,
+            object=object,
+            sensor=sensor,
+            points=[
+                raillabel.format.Point2d(1, 0),
+                raillabel.format.Point2d(1, 1),
+            ],
+            closed=False,
+            attributes={"railSide": "rightRail"},
+        )
+
+    results = _count_rails_per_track_in_frame(frame)
+    assert len(results) == 1
+    assert object.uid in results.keys()
+    assert results[object.uid] == (LEFT_COUNT, RIGHT_COUNT)
+
+
+def test_count_rails_per_track_in_frame__many_rails_for_two_tracks(
+    empty_frame, example_camera_1, example_track_1, example_track_2
+):
+    frame = empty_frame
+    sensor = example_camera_1
+    object1 = example_track_1
+    object2 = example_track_2
+
+    LEFT_COUNT = 32
+    RIGHT_COUNT = 42
+
+    for object in [object1, object2]:
+        for i in range(LEFT_COUNT):
+            uid = f"test_left_{i}_object_{object.uid}"
+            frame.annotations[uid] = raillabel.format.Poly2d(
+                uid=uid,
+                object=object,
+                sensor=sensor,
+                points=[
+                    raillabel.format.Point2d(0, 0),
+                    raillabel.format.Point2d(0, 1),
+                ],
+                closed=False,
+                attributes={"railSide": "leftRail"},
+            )
+
+        for i in range(RIGHT_COUNT):
+            uid = f"test_right_{i}_object_{object.uid}"
+            frame.annotations[uid] = raillabel.format.Poly2d(
+                uid=uid,
+                object=object,
+                sensor=sensor,
+                points=[
+                    raillabel.format.Point2d(1, 0),
+                    raillabel.format.Point2d(1, 1),
+                ],
+                closed=False,
+                attributes={"railSide": "rightRail"},
+            )
+
+    results = _count_rails_per_track_in_frame(frame)
+    assert len(results) == 2
+    assert object1.uid in results.keys()
+    assert object2.uid in results.keys()
+    assert results[object1.uid] == (LEFT_COUNT, RIGHT_COUNT)
+    assert results[object2.uid] == (LEFT_COUNT, RIGHT_COUNT)
+
+
+def test_validate_rail_side__no_errors(empty_scene, empty_frame, example_camera_1, example_track_1):
+    scene = empty_scene
+    object = example_track_1
+    scene.objects[object.uid] = object
+    sensor = example_camera_1
     scene.sensors[sensor.uid] = sensor
     frame = empty_frame
     frame.annotations["325b1f55-a2ef-475f-a780-13e1a9e823c3"] = raillabel.format.Poly2d(
@@ -49,16 +173,13 @@ def test_validate_rail_side__no_errors(empty_scene, empty_frame):
     assert len(actual) == 0
 
 
-def test_validate_rail_side__rail_sides_switched(empty_scene, empty_frame):
+def test_validate_rail_side__rail_sides_switched(
+    empty_scene, empty_frame, example_camera_1, example_track_1
+):
     scene = empty_scene
-    object = raillabel.format.Object(
-        uid="a1082ef9-555b-4b69-a888-7da531d8a2eb", name="track0001", type="track"
-    )
+    object = example_track_1
     scene.objects[object.uid] = object
-    sensor = raillabel.format.Sensor(
-        uid="rgb_center",
-        type=raillabel.format.SensorType.CAMERA,
-    )
+    sensor = example_camera_1
     scene.sensors[sensor.uid] = sensor
     frame = empty_frame
     frame.annotations["325b1f55-a2ef-475f-a780-13e1a9e823c3"] = raillabel.format.Poly2d(
@@ -89,16 +210,13 @@ def test_validate_rail_side__rail_sides_switched(empty_scene, empty_frame):
     assert len(actual) == 1
 
 
-def test_validate_rail_side__two_left_rails(empty_scene, empty_frame):
+def test_validate_rail_side__two_left_rails(
+    empty_scene, empty_frame, example_camera_1, example_track_1
+):
     scene = empty_scene
-    object = raillabel.format.Object(
-        uid="a1082ef9-555b-4b69-a888-7da531d8a2eb", name="track0001", type="track"
-    )
+    object = example_track_1
     scene.objects[object.uid] = object
-    sensor = raillabel.format.Sensor(
-        uid="rgb_center",
-        type=raillabel.format.SensorType.CAMERA,
-    )
+    sensor = example_camera_1
     scene.sensors[sensor.uid] = sensor
     frame = empty_frame
     frame.annotations["325b1f55-a2ef-475f-a780-13e1a9e823c3"] = raillabel.format.Poly2d(
@@ -129,16 +247,13 @@ def test_validate_rail_side__two_left_rails(empty_scene, empty_frame):
     assert len(actual) == 1
 
 
-def test_validate_rail_side__two_right_rails(empty_scene, empty_frame):
+def test_validate_rail_side__two_right_rails(
+    empty_scene, empty_frame, example_camera_1, example_track_1
+):
     scene = empty_scene
-    object = raillabel.format.Object(
-        uid="a1082ef9-555b-4b69-a888-7da531d8a2eb", name="track0001", type="track"
-    )
+    object = example_track_1
     scene.objects[object.uid] = object
-    sensor = raillabel.format.Sensor(
-        uid="rgb_center",
-        type=raillabel.format.SensorType.CAMERA,
-    )
+    sensor = example_camera_1
     scene.sensors[sensor.uid] = sensor
     frame = empty_frame
     frame.annotations["325b1f55-a2ef-475f-a780-13e1a9e823c3"] = raillabel.format.Poly2d(
@@ -169,20 +284,14 @@ def test_validate_rail_side__two_right_rails(empty_scene, empty_frame):
     assert len(actual) == 1
 
 
-def test_validate_rail_side__two_sensors_with_two_right_rails_each(empty_scene, empty_frame):
+def test_validate_rail_side__two_sensors_with_two_right_rails_each(
+    empty_scene, empty_frame, example_camera_1, example_camera_2, example_track_1
+):
     scene = empty_scene
-    object = raillabel.format.Object(
-        uid="a1082ef9-555b-4b69-a888-7da531d8a2eb", name="track0001", type="track"
-    )
+    object = example_track_1
     scene.objects[object.uid] = object
-    sensor1 = raillabel.format.Sensor(
-        uid="rgb_center",
-        type=raillabel.format.SensorType.CAMERA,
-    )
-    sensor2 = raillabel.format.Sensor(
-        uid="ir_center",
-        type=raillabel.format.SensorType.CAMERA,
-    )
+    sensor1 = example_camera_1
+    sensor2 = example_camera_2
     for sensor in [sensor1, sensor2]:
         scene.sensors[sensor.uid] = sensor
     frame = empty_frame
@@ -236,20 +345,14 @@ def test_validate_rail_side__two_sensors_with_two_right_rails_each(empty_scene,
     assert len(actual) == 2
 
 
-def test_validate_rail_side__two_sensors_with_one_right_rail_each(empty_scene, empty_frame):
+def test_validate_rail_side__two_sensors_with_one_right_rail_each(
+    empty_scene, empty_frame, example_camera_1, example_camera_2, example_track_1
+):
     scene = empty_scene
-    object = raillabel.format.Object(
-        uid="a1082ef9-555b-4b69-a888-7da531d8a2eb", name="track0001", type="track"
-    )
+    object = example_track_1
     scene.objects[object.uid] = object
-    sensor1 = raillabel.format.Sensor(
-        uid="rgb_center",
-        type=raillabel.format.SensorType.CAMERA,
-    )
-    sensor2 = raillabel.format.Sensor(
-        uid="ir_center",
-        type=raillabel.format.SensorType.CAMERA,
-    )
+    sensor1 = example_camera_1
+    sensor2 = example_camera_2
     for sensor in [sensor1, sensor2]:
         scene.sensors[sensor.uid] = sensor
     frame = empty_frame