diff --git a/src/edu/kit/informatik/model/TrainManager.java b/src/edu/kit/informatik/model/TrainManager.java
index 6ef1fec..82441a5 100644
--- a/src/edu/kit/informatik/model/TrainManager.java
+++ b/src/edu/kit/informatik/model/TrainManager.java
@@ -249,12 +249,8 @@ public final class TrainManager {
      */
     private List<Set<Train>> getCollisionsOfOneReverseStep() {
         List<Set<Train>> collisions = new ArrayList<>();
-        Map<Train, Set<Rail>> occupiedRails = new HashMap<>();
-        for (Train train : trains.values()) {
-            if (train.isPlaced()) {
-                occupiedRails.put(train, train.getOccupiedRails());
-            }
-        }
+        Map<Train, Set<Rail>> occupiedRails = trains.values().stream().filter(Train::isPlaced)
+                .collect(Collectors.toMap(Function.identity(), Train::getOccupiedRails));
         // perform step
         Map<Train, Set<Rail>> nextOccupiedRails = new HashMap<>();
         trains.values().stream().filter(Train::isPlaced).forEach(train -> {