diff --git a/src/edu/kit/informatik/CommandLine.java b/src/edu/kit/informatik/CommandLine.java
index 72098d6..4369ace 100644
--- a/src/edu/kit/informatik/CommandLine.java
+++ b/src/edu/kit/informatik/CommandLine.java
@@ -13,16 +13,14 @@ public class CommandLine {
     private static final String EXIT = "exit";
 
     public static void startInteractive() {
+        // create a new simulation
         ModelRailwaySimulation simulation = new ModelRailwaySimulation();
 
         while (true) {
             final String input = Terminal.readLine();
-            if (input == null) {
+            if (input == null || input.startsWith("#")) {
                 break; // TODO remove
             }
-            if (input.startsWith("#")) {
-                continue; // TODO remove
-            }
 
             if (input.equals(EXIT)) {
                 break;
@@ -30,7 +28,6 @@ public class CommandLine {
 
             final Command command;
             try {
-                //Terminal.printLine("> " + input);
                 command = CommandFactory.getCommand(input);
             } catch (NumberFormatException e) {
                 Terminal.printError("number too big");
diff --git a/src/edu/kit/informatik/ModelRailwaySimulation.java b/src/edu/kit/informatik/ModelRailwaySimulation.java
index e05a936..0640fb5 100644
--- a/src/edu/kit/informatik/ModelRailwaySimulation.java
+++ b/src/edu/kit/informatik/ModelRailwaySimulation.java
@@ -11,10 +11,10 @@ public class ModelRailwaySimulation {
     private List<Train> trains = new ArrayList<>();
 
     /**
-     * Identifier if success, -1 if fail
-     * @param start
-     * @param end
-     * @return
+     * Add a new track to the rail network of this simulation.
+     * @param start start position of the new track
+     * @param end end position of the new track
+     * @return the positive identifier of the new track if successful, -1 otherwise
      */
     public int addTrack(final Vector2D start, final Vector2D end) {
         if (start.distanceTo(end) == 0) {
@@ -46,11 +46,11 @@ public class ModelRailwaySimulation {
     }
 
     /**
-     * -1 if fail
-     * @param start
-     * @param end1
-     * @param end2
-     * @return
+     * Add a switch to the rail network of this simulation.
+     * @param start start point of the switch
+     * @param end1 end position 1 of the switch
+     * @param end2 end position 2 of the switch
+     * @return the positive identifier of the switch if successful, -1 otherwise
      */
     public int addSwitch(final Vector2D start, final Vector2D end1, final Vector2D end2) {
         if (start.distanceTo(end1) == 0 || start.distanceTo(end2) == 0 || end1.distanceTo(end2) == 0) {
@@ -97,9 +97,9 @@ public class ModelRailwaySimulation {
     }
 
     /**
-     * true success, false fail
-     * @param id
-     * @return
+     * Remove the specified rail from the rail network.
+     * @param id identifier of the rail to remove
+     * @return true if rail could be successfully removed, false otherwise
      */
     public boolean removeRail(final int id) {
         if (rails.size() == 0) {
@@ -168,10 +168,10 @@ public class ModelRailwaySimulation {
     }
 
     /**
-     * true success, false fail
-     * @param id
-     * @param position
-     * @return
+     * Change the setting of a switch in the rail network.
+     * @param id identifier of the switch
+     * @param position position to set the switch to
+     * @return whether the switch could be set
      */
     public boolean setSwitch(int id, Vector2D position) {
         // TODO Falls Gleiseweichen auf denen ein Zug bereitssteht, geschaltet werden, entgleist der daraufstehende Zug
@@ -184,9 +184,8 @@ public class ModelRailwaySimulation {
     }
 
     /**
-     * true success, false fail
-     * @param newEngine
-     * @return
+     * @param newEngine the engine to add to the simulation
+     * @return whether adding this engine was successful
      */
     public boolean createEngine(final Engine newEngine) {
         String id = newEngine.getIdentifier();
@@ -223,8 +222,12 @@ public class ModelRailwaySimulation {
     }
 
     /**
-     * positive success, -1 fail
-     * @return
+     * Add a new coach to the simulation.
+     * @param coachType type of the coach
+     * @param length length of the coach
+     * @param couplingFront whether the coach should have a front coupling
+     * @param couplingBack whether the coach should have a back coupling
+     * @return the identifier of the coach if successfully added, -1 otherwise
      */
     public int createCoach(final CoachType coachType, final int length,
                            final boolean couplingFront, final boolean couplingBack) {
@@ -267,9 +270,9 @@ public class ModelRailwaySimulation {
     }
 
     /**
-     * true success, false fail
-     * @param newTrainSet
-     * @return
+     * Add a new train set to the simulation.
+     * @param newTrainSet the train set to add
+     * @return true if the train set was successfully added, false otherwise
      */
     public boolean createTrainSet(final TrainSet newTrainSet) {
         String id = newTrainSet.getIdentifier();
@@ -305,9 +308,9 @@ public class ModelRailwaySimulation {
     }
 
     /**
-     * true success, false fail
-     * @param id
-     * @return
+     * Delete a rolling stock.
+     * @param id identifier of the rolling stock to remove
+     * @return whether the rolling was successfully removed
      */
     public boolean deleteRollingStock(String id) {
         RollingStock rollingStock = getRollingStock(id);
@@ -422,11 +425,11 @@ public class ModelRailwaySimulation {
     }
 
     /**
-     * true success, false fail
-     * @param trainId
-     * @param position
-     * @param rawDirection
-     * @return
+     * Put a train on the rail network.
+     * @param trainId identifier of the train to place
+     * @param position where to place the train
+     * @param rawDirection direction in which the train should initially go
+     * @return whether the train was successfully placed
      */
     public boolean putTrain(final int trainId, final Vector2D position, final Vector2D rawDirection) {
         final Vector2D direction = rawDirection.normalized();
@@ -727,11 +730,11 @@ public class ModelRailwaySimulation {
                     continue;
                 }
                 List<Train> collision = collisionSet.stream().sorted(Comparator.comparing(Train::getIdentifier))
-                        .collect(Collectors.toList());
+                    .collect(Collectors.toList());
                 if (collision.indexOf(train) == 0) {
                     Terminal.printLine("Crash of train " + String.join(",",
                             collision.stream().map(
-                                    (x) -> Integer.toString(x.getIdentifier())).toArray(String[]::new)));
+                                (x) -> Integer.toString(x.getIdentifier())).toArray(String[]::new)));
                 }
                 continue train;
             }
diff --git a/src/edu/kit/informatik/Rail.java b/src/edu/kit/informatik/Rail.java
index 599581c..c342482 100644
--- a/src/edu/kit/informatik/Rail.java
+++ b/src/edu/kit/informatik/Rail.java
@@ -7,7 +7,14 @@ package edu.kit.informatik;
  * @version 1.0
  */
 public abstract class Rail {
-    protected int id;
+    /**
+     * Unique identifier of this rail.
+     */
+    protected final int id;
+
+    protected Rail(final int id) {
+        this.id = id;
+    }
 
     public int getIdentifier() {
         return this.id;
@@ -32,9 +39,9 @@ public abstract class Rail {
     public abstract boolean canConnectToRail(Rail rail);
 
     /**
-     * true success, false fail
-     * @param position
-     * @return
+     * Try to set the rail to connect to this position. Obviously only makes sense for switches and similar rails.
+     * @param position point to connect to
+     * @return whether rail could be successfully set
      */
     public abstract boolean switchTo(Vector2D position);
 
diff --git a/src/edu/kit/informatik/RollingStock.java b/src/edu/kit/informatik/RollingStock.java
index 0c46988..101a8e7 100644
--- a/src/edu/kit/informatik/RollingStock.java
+++ b/src/edu/kit/informatik/RollingStock.java
@@ -1,8 +1,23 @@
 package edu.kit.informatik;
 
+/**
+ * A rolling stock. Is usually an engine, train set or coach.
+ *
+ * @author Arne Keller
+ * @version 1.0
+ */
 public abstract class RollingStock {
+    /**
+     * Length of this rolling stock.
+     */
     protected int length;
+    /**
+     * Whether this rolling stock has a front coupling.
+     */
     protected boolean couplingFront;
+    /**
+     * Whether this rolling stack has a back coupling.
+     */
     protected boolean couplingBack;
 
     public abstract String getIdentifier();
diff --git a/src/edu/kit/informatik/Switch.java b/src/edu/kit/informatik/Switch.java
index ebfb99b..732e599 100644
--- a/src/edu/kit/informatik/Switch.java
+++ b/src/edu/kit/informatik/Switch.java
@@ -35,6 +35,7 @@ public final class Switch extends Rail {
      * @throws IllegalArgumentException if the switch is not composed of straight lines
      */
     public Switch(Vector2D start, Vector2D end1, Vector2D end2, int id) throws IllegalArgumentException {
+        super(id);
         if (start.getX() != end1.getX() && start.getY() != end1.getY()
             || start.getX() != end2.getX() && start.getY() != end2.getY()) {
             throw new IllegalArgumentException("start has to be connected in straight lines to end positions!");
@@ -42,7 +43,6 @@ public final class Switch extends Rail {
         this.start = start;
         this.end1 = end1;
         this.end2 = end2;
-        super.id = id;
     }
 
     @Override
diff --git a/src/edu/kit/informatik/Track.java b/src/edu/kit/informatik/Track.java
index 0c793fc..957cef9 100644
--- a/src/edu/kit/informatik/Track.java
+++ b/src/edu/kit/informatik/Track.java
@@ -20,12 +20,12 @@ public final class Track extends Rail {
      * @throws IllegalArgumentException if the positions are not on a straight line
      */
     public Track(final Vector2D start, final Vector2D end, final int id) throws IllegalArgumentException {
+        super(id);
         if (start.getX() != end.getX() && start.getY() != end.getY()) {
             throw new IllegalArgumentException("start and end have to be in a straight line!");
         }
         this.start = start;
         this.end = end;
-        super.id = id;
     }
 
     @Override
diff --git a/src/edu/kit/informatik/Train.java b/src/edu/kit/informatik/Train.java
index ede941f..e1190a8 100644
--- a/src/edu/kit/informatik/Train.java
+++ b/src/edu/kit/informatik/Train.java
@@ -34,9 +34,9 @@ public final class Train {
     }
 
     /**
-     * true success, false fail
-     * @param rollingStock
-     * @return
+     * Add a rolling stock to this train.
+     * @param rollingStock the rolling stack to add
+     * @return whether the modification was successful
      */
     public boolean add(RollingStock rollingStock) {
         if (rollingStock.canCoupleFrontTo(rollingStocks.get(rollingStocks.size() - 1))) {
diff --git a/src/edu/kit/informatik/command/CommandFactory.java b/src/edu/kit/informatik/command/CommandFactory.java
index 25069eb..d8b5e90 100644
--- a/src/edu/kit/informatik/command/CommandFactory.java
+++ b/src/edu/kit/informatik/command/CommandFactory.java
@@ -82,7 +82,8 @@ public class CommandFactory {
             Vector2D start = Vector2D.parse(matcher.group(1));
             Vector2D end1 = Vector2D.parse(matcher.group(2));
             Vector2D end2 = Vector2D.parse(matcher.group(3));
-            if ((start.getX() == end1.getX() || start.getY() == end1.getY()) && (start.getX() == end2.getX() || start.getY() == end2.getY())) {
+            if ((start.getX() == end1.getX() || start.getY() == end1.getY())
+                    && (start.getX() == end2.getX() || start.getY() == end2.getY())) {
                 return new AddSwitch(start, end1, end2);
             } else {
                 throw new InvalidInputException("switch rails have to be straight lines");