diff --git a/src/edu/kit/informatik/model/ModelRailwaySimulation.java b/src/edu/kit/informatik/model/ModelRailwaySimulation.java
index 46be686..736fc78 100644
--- a/src/edu/kit/informatik/model/ModelRailwaySimulation.java
+++ b/src/edu/kit/informatik/model/ModelRailwaySimulation.java
@@ -71,7 +71,7 @@ public class ModelRailwaySimulation {
      */
     public boolean removeRail(int id) {
         // check whether any trains are on this rail
-        return railNetwork.getRail(id).isPresent() && !trainManager.anyTrainOnRail(railNetwork.getRail(id).get())
+        return !railNetwork.getRail(id).map(trainManager::anyTrainOnRail).orElse(true)
                 && railNetwork.removeRail(id);
     }
 
@@ -250,16 +250,19 @@ public class ModelRailwaySimulation {
 
     /**
      * Create a new train or add rolling stock to an existing train.
+     *
      * @param trainId identifier of the train
      * @param rollingStockId identifier of the rolling stock
+     * @return the added rolling stock
      * @throws InvalidInputException if input is incorrect
      */
-    public void addTrain(int trainId, String rollingStockId) throws InvalidInputException {
+    public RollingStock addTrain(int trainId, String rollingStockId) throws InvalidInputException {
         final Optional<RollingStock> rollingStock = getRollingStock(rollingStockId);
         if (!rollingStock.isPresent()) {
             throw new InvalidInputException("rolling stock not found");
         }
         trainManager.addTrain(trainId, rollingStock.get());
+        return rollingStock.get();
     }
 
     /**
diff --git a/src/edu/kit/informatik/model/Train.java b/src/edu/kit/informatik/model/Train.java
index 11242a5..e668320 100644
--- a/src/edu/kit/informatik/model/Train.java
+++ b/src/edu/kit/informatik/model/Train.java
@@ -153,9 +153,9 @@ public final class Train {
             length -= distanceToLastPosition;
 
             final Rail occupiedRail = railNetwork.findRail(positionList.getLast(), rollingStockPosition).get();
-            if (occupiedRailsSet.contains(occupiedRail) && positionList.size() >= 4) {
+            if (occupiedRailsSet.contains(occupiedRail) && positionList.size() > 4) {
                 // perhaps a self intersection
-                final long occupiedAtFrontOfTrain = positionList.get(0).distanceTo(positionList.get(1));
+                final long occupiedAtFrontOfTrain = positionList.getFirst().distanceTo(positionList.get(1));
                 final long occupiedAtBackOfTrain = positionList.getLast()
                         .distanceTo(positionList.get(positionList.size() - 2));
                 if (occupiedAtFrontOfTrain + occupiedAtBackOfTrain > occupiedRail.getLength()) {
@@ -269,6 +269,7 @@ public final class Train {
      * @param backPosition position to move back of the train to
      */
     public void moveBackTo(RailwayNetwork railNetwork, Vector2D backPosition) {
+        // TODO: create common method for both directions
         final Optional<Rail> railUnderFrontOfTrain = railNetwork.findContainingRail(positions.getFirst());
         positions.getFirst().subtractInPlace(getDirection());
         if (positions.getFirst().equals(positions.get(1))) {
diff --git a/src/edu/kit/informatik/ui/CommandLine.java b/src/edu/kit/informatik/ui/CommandLine.java
index 1720d66..e832d4f 100644
--- a/src/edu/kit/informatik/ui/CommandLine.java
+++ b/src/edu/kit/informatik/ui/CommandLine.java
@@ -32,10 +32,10 @@ public final class CommandLine {
         while (true) {
             final String input = Terminal.readLine();
             if (input == null) {
-                break; // TODO remove
+                break; // FIXME remove
             }
             if (input.startsWith("#")) {
-                continue; // TODO remove
+                continue; // FIXME remove
             }
 
             if (input.startsWith(EXIT)) {
@@ -43,7 +43,7 @@ public final class CommandLine {
                     Terminal.printError("input after exit command");
                     continue;
                 } else {
-                    break;
+                    return;
                 }
             }
 
diff --git a/src/edu/kit/informatik/ui/command/AddTrain.java b/src/edu/kit/informatik/ui/command/AddTrain.java
index b598183..1ad6606 100644
--- a/src/edu/kit/informatik/ui/command/AddTrain.java
+++ b/src/edu/kit/informatik/ui/command/AddTrain.java
@@ -36,8 +36,7 @@ public class AddTrain extends Command {
         if (rollingStockId == null) {
             throw new IllegalStateException("command not initialized");
         }
-        simulation.addTrain(trainId, rollingStockId);
-        final RollingStock rollingStock = simulation.getRollingStock(rollingStockId).get();
+        final RollingStock rollingStock = simulation.addTrain(trainId, rollingStockId);
         Terminal.printLine(String.format("%s %s added to train %d",
                 rollingStock.description(), rollingStock.getIdentifier(), trainId));
     }