diff --git a/src/main/org/insa/graph/Arc.java b/src/main/org/insa/graph/Arc.java
index 9d2eb16..5140884 100644
--- a/src/main/org/insa/graph/Arc.java
+++ b/src/main/org/insa/graph/Arc.java
@@ -7,6 +7,11 @@ import java.util.List;
  * class to allow us to represent two-ways roads in a memory efficient manner
  * (without having to duplicate attributes).
  * 
+ * Arc should never be created manually but always using the
+ * {@link Node#linkNodes(Node, Node, int, RoadInformation, java.util.ArrayList)}
+ * method to ensure proper instantiation of the {@link ArcForward} and
+ * {@link ArcBackward} classes.
+ * 
  * @see ArcForward
  * @see ArcBackward
  *
diff --git a/src/main/org/insa/graph/ArcBackward.java b/src/main/org/insa/graph/ArcBackward.java
index 36c841a..4a0aaaf 100644
--- a/src/main/org/insa/graph/ArcBackward.java
+++ b/src/main/org/insa/graph/ArcBackward.java
@@ -10,7 +10,7 @@ import java.util.List;
  * the original arc.
  *
  */
-public class ArcBackward implements Arc {
+class ArcBackward implements Arc {
 
     // Original arc
     private final ArcForward originalArc;
@@ -19,9 +19,9 @@ public class ArcBackward implements Arc {
      * Create a new backward arc which corresponds to the reverse arc of the given
      * arc.
      * 
-     * @param originalArc
+     * @param originalArc Original forwarc arc corresponding to this backward arc.
      */
-    public ArcBackward(ArcForward originalArc) {
+    protected ArcBackward(ArcForward originalArc) {
         this.originalArc = originalArc;
         this.originalArc.getDestination().addSuccessor(this);
     }
diff --git a/src/main/org/insa/graph/ArcForward.java b/src/main/org/insa/graph/ArcForward.java
index afd8173..ff20a77 100644
--- a/src/main/org/insa/graph/ArcForward.java
+++ b/src/main/org/insa/graph/ArcForward.java
@@ -24,7 +24,7 @@ public class ArcForward implements Arc {
     private final ArrayList<Point> points;
 
     /**
-     * Create a new arc and automatically link it with the given origin.
+     * Create a new ArcForward with the given attributes.
      * 
      * @param origin Origin of this arc.
      * @param dest Destination of this arc.
@@ -32,54 +32,44 @@ public class ArcForward implements Arc {
      * @param roadInformation Road information for this arc.
      * @param points Points representing this arc.
      */
-    public ArcForward(Node origin, Node dest, int length, RoadInformation roadInformation,
+    protected ArcForward(Node origin, Node dest, int length, RoadInformation roadInformation,
             ArrayList<Point> points) {
         this.origin = origin;
         this.destination = dest;
         this.length = length;
         this.info = roadInformation;
         this.points = points;
-        origin.addSuccessor(this);
     }
 
-    /**
-     * {@inheritDoc}
-     */
+    @Override
     public Node getOrigin() {
         return origin;
     }
 
-    /**
-     * {@inheritDoc}
-     */
+    @Override
     public Node getDestination() {
         return destination;
     }
 
-    /**
-     * {@inheritDoc}
-     */
+    @Override
+
     public int getLength() {
         return length;
     }
 
-    /**
-     * {@inheritDoc}
-     */
+    @Override
+
     public double getMinimumTravelTime() {
         return getLength() * 3600.0 / (info.getMaximumSpeed() * 1000.0);
     }
 
-    /**
-     * {@inheritDoc}
-     */
+    @Override
+
     public RoadInformation getRoadInformation() {
         return info;
     }
 
-    /**
-     * {@inheritDoc}
-     */
+    @Override
     public List<Point> getPoints() {
         return Collections.unmodifiableList(points);
     }
diff --git a/src/main/org/insa/graph/Graph.java b/src/main/org/insa/graph/Graph.java
index b96e5ea..09986b6 100644
--- a/src/main/org/insa/graph/Graph.java
+++ b/src/main/org/insa/graph/Graph.java
@@ -3,6 +3,13 @@ package org.insa.graph;
 import java.util.Collections;
 import java.util.List;
 
+/**
+ * Main graph class.
+ * 
+ * This class acts as a object-oriented adjacency list for a graph, i.e. it
+ * holds a list of nodes and each node holds a list of its successors.
+ *
+ */
 public class Graph {
 
     // Map identifier.
@@ -15,35 +22,39 @@ public class Graph {
     private final List<Node> nodes;
 
     // Graph information of this graph.
-    private final GraphInformation graphInfo;
+    private final GraphStatistics graphStatistics;
 
     /**
-     * @param mapId ID of this graph.
-     * @param list List of nodes for this graph.
+     * Create a new graph with the given ID, name, nodes and information.
+     * 
+     * @param mapId ID of the map corresponding to this graph.
+     * @param mapName Name of the map corresponding to this graph.
+     * @param nodes List of nodes for this graph.
+     * @param graphStatistics Information for this graph.
      */
-    public Graph(String mapId, String mapName, List<Node> list, GraphInformation graphInformation) {
+    public Graph(String mapId, String mapName, List<Node> nodes, GraphStatistics graphStatistics) {
         this.mapId = mapId;
         this.mapName = mapName;
-        this.nodes = list;
-        this.graphInfo = graphInformation;
+        this.nodes = nodes;
+        this.graphStatistics = graphStatistics;
     }
 
     /**
-     * @return GraphInformation of this graph.
+     * @return The GraphStatistics instance associated with this graph.
      */
-    public GraphInformation getGraphInformation() {
-        return this.graphInfo;
+    public GraphStatistics getGraphInformation() {
+        return this.graphStatistics;
     }
 
     /**
-     * @return Immutable list of nodes of this graph.
+     * @return Immutable view of the list of nodes of this graph.
      */
     public List<Node> getNodes() {
         return Collections.unmodifiableList(nodes);
     }
 
     /**
-     * @return Map ID of this graph.
+     * @return ID of the map associated with this graph.
      */
     public String getMapId() {
         return mapId;
@@ -57,7 +68,7 @@ public class Graph {
     }
 
     /**
-     * @return Return the transpose graph of this graph.
+     * @return Transpose graph of this graph.
      */
     public Graph transpose() {
         // TODO:
diff --git a/src/main/org/insa/graph/GraphInformation.java b/src/main/org/insa/graph/GraphInformation.java
deleted file mode 100644
index 1d49b40..0000000
--- a/src/main/org/insa/graph/GraphInformation.java
+++ /dev/null
@@ -1,39 +0,0 @@
-package org.insa.graph;
-
-/**
- * Utility class that stores some information for a graph that are no easy to
- * access quickly.
- *
- */
-public class GraphInformation {
-
-    // Maximum speed on this graph (in kmph).
-    private final int maximumSpeed;
-
-    // Maximum length of any arc on this graph.
-    private final int maximumLength;
-
-    /**
-     * @param maximumSpeed
-     * @param maximumLength
-     */
-    public GraphInformation(int maximumSpeed, int maximumLength) {
-        this.maximumLength = maximumLength;
-        this.maximumSpeed = maximumSpeed;
-    }
-
-    /**
-     * @return Maximum speed of any arc in the graph.
-     */
-    public int getMaximumSpeed() {
-        return this.maximumSpeed;
-    }
-
-    /**
-     * @return Maximum length of any arc in the graph.
-     */
-    public int getMaximumLength() {
-        return this.maximumLength;
-    }
-
-}
diff --git a/src/main/org/insa/graph/GraphStatistics.java b/src/main/org/insa/graph/GraphStatistics.java
new file mode 100644
index 0000000..fa6d115
--- /dev/null
+++ b/src/main/org/insa/graph/GraphStatistics.java
@@ -0,0 +1,46 @@
+package org.insa.graph;
+
+/**
+ * Utility class that stores some statistics of graphs that are not easy to
+ * access.
+ * 
+ * This class is used to provide O(1) access to information in graph that do not
+ * change, and that usually require O(n) to compute.
+ *
+ */
+public class GraphStatistics {
+
+    // Maximum speed on this graph (in kmph).
+    private final int maximumSpeed;
+
+    // Maximum length of any arc on this graph.
+    private final int maximumLength;
+
+    /**
+     * Create a new GraphStatistics instance with the given value.
+     * 
+     * @param maximumSpeed Maximum speed of any road of the graph. A value of 0 may
+     * be used to indicate that this graph has no maximum limitation.
+     * @param maximumLength Maximum length of any arc of the graph.
+     */
+    public GraphStatistics(int maximumSpeed, int maximumLength) {
+        this.maximumLength = maximumLength;
+        this.maximumSpeed = maximumSpeed;
+    }
+
+    /**
+     * @return Maximum speed of any arc in the graph, or 0 if some road have no
+     * speed limitations.
+     */
+    public int getMaximumSpeed() {
+        return this.maximumSpeed;
+    }
+
+    /**
+     * @return Maximum length of any arc in the graph.
+     */
+    public int getMaximumLength() {
+        return this.maximumLength;
+    }
+
+}
diff --git a/src/main/org/insa/graph/Node.java b/src/main/org/insa/graph/Node.java
index 6a93bdc..9620cfe 100644
--- a/src/main/org/insa/graph/Node.java
+++ b/src/main/org/insa/graph/Node.java
@@ -4,8 +4,43 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
+/**
+ * Class representing a Node in a {@link Graph}.
+ * 
+ * This class holds information regarding nodes in the graph together with the
+ * successors associated to the nodes.
+ * 
+ * Nodes are comparable based on their ID.
+ *
+ */
 public class Node implements Comparable<Node> {
 
+    /**
+     * Link the two given nodes with one or two arcs (depending on roadInformation),
+     * with the given attributes.
+     * 
+     * If `roadInformation.isOneWay()` is true, only a forward arc is created
+     * (origin to destination) and added to origin. Otherwise, a corresponding
+     * backward arc is created and add to destination.
+     * 
+     * @param origin Origin of the arc.
+     * @param destination Destination of the arc.
+     * @param length Length of the arc.
+     * @param roadInformation Information corresponding to the arc.
+     * @param points Points for the arc.
+     * 
+     * @return The newly created forward arc (origin to destination).
+     */
+    public static Arc linkNodes(Node origin, Node destination, int length,
+            RoadInformation roadInformation, ArrayList<Point> points) {
+        ArcForward arc = new ArcForward(origin, destination, length, roadInformation, points);
+        origin.addSuccessor(arc);
+        if (!roadInformation.isOneWay()) {
+            destination.addSuccessor(new ArcBackward(arc));
+        }
+        return arc;
+    }
+
     // ID of the node.
     private final int id;
 
@@ -16,10 +51,11 @@ public class Node implements Comparable<Node> {
     private final ArrayList<Arc> successors;
 
     /**
-     * Create a new Node corresponding to the given Point with an empty list of
-     * successors.
+     * Create a new Node with the given ID corresponding to the given Point with an
+     * empty list of successors.
      * 
-     * @param point
+     * @param id ID of the node.
+     * @param point Position of the node.
      */
     public Node(int id, Point point) {
         this.id = id;
@@ -44,24 +80,19 @@ public class Node implements Comparable<Node> {
     }
 
     /**
-     * @return List of successors of this node.
+     * @return Immutable view of the list of successors of this node.
      */
     public List<Arc> getSuccessors() {
         return Collections.unmodifiableList(successors);
     }
 
     /**
-     * @return Point of this node.
+     * @return Location of this node.
      */
     public Point getPoint() {
         return point;
     }
 
-    /*
-     * (non-Javadoc)
-     * 
-     * @see java.lang.Object#equals(java.lang.Object)
-     */
     @Override
     public boolean equals(Object other) {
         if (other instanceof Node) {
@@ -70,8 +101,10 @@ public class Node implements Comparable<Node> {
         return false;
     }
 
-    /*
-     * (non-Javadoc)
+    /**
+     * Compare the ID of this node with the ID of the given node.
+     * 
+     * @param other Node to compare this node with.
      * 
      * @see java.lang.Comparable#compareTo(java.lang.Object)
      */
diff --git a/src/main/org/insa/graph/Point.java b/src/main/org/insa/graph/Point.java
index 6a0db35..509c4f9 100644
--- a/src/main/org/insa/graph/Point.java
+++ b/src/main/org/insa/graph/Point.java
@@ -1,20 +1,23 @@
 package org.insa.graph;
 
 /**
- * Class representing a point on Earth.
+ * Class representing a point (position) on Earth.
  *
  */
 public final class Point {
 
-    // Earth radius, in meters;
-    private static final double EARTH_RADIUS = 6378137.0;
+    /**
+     * Approximated Earth radius (in meters).
+     */
+    public static final double EARTH_RADIUS = 6378137.0;
 
     /**
      * Compute the distance in meters between the two given points.
      * 
-     * @param p1, p2
+     * @param p1 First point.
+     * @param p2 second point.
      * 
-     * @return Distance between the two given points, in meters.
+     * @return Distance between the two given points (in meters).
      */
     public static double distance(Point p1, Point p2) {
         double sinLat = Math.sin(Math.toRadians(p1.getLatitude()))
@@ -29,9 +32,10 @@ public final class Point {
     private final float longitude, latitude;
 
     /**
+     * Create a new point corresponding to the given (longitude, latitude) position.
      * 
-     * @param longitude Longitude of the point, in degrees.
-     * @param latitude Latitude of the point, in degrees.
+     * @param longitude Longitude of the point (in degrees).
+     * @param latitude Latitude of the point (in degrees).
      */
     public Point(float longitude, float latitude) {
         this.longitude = longitude;
@@ -55,7 +59,7 @@ public final class Point {
     /**
      * Compute the distance from this point to the given point
      * 
-     * @param target Target point.
+     * @param target Target point to compute distance to.
      * 
      * @return Distance between this point and the target point, in meters.
      */
@@ -63,11 +67,6 @@ public final class Point {
         return distance(this, target);
     }
 
-    /*
-     * (non-Javadoc)
-     * 
-     * @see java.lang.Object#toString()
-     */
     @Override
     public String toString() {
         return String.format("Point(%f, %f)", getLongitude(), getLatitude());
diff --git a/src/main/org/insa/graph/RoadInformation.java b/src/main/org/insa/graph/RoadInformation.java
index 1a2ad3a..fd6c3b4 100644
--- a/src/main/org/insa/graph/RoadInformation.java
+++ b/src/main/org/insa/graph/RoadInformation.java
@@ -3,6 +3,9 @@ package org.insa.graph;
 /**
  * Class containing information for road that may be shared by multiple arcs.
  * 
+ * Sharing information between arcs reduces memory footprints of the program - A
+ * long road is often split into multiple arcs at each intersection.
+ * 
  */
 public class RoadInformation {
 
@@ -45,6 +48,16 @@ public class RoadInformation {
     // Name of the road.
     private final String name;
 
+    /**
+     * Create a new RoadInformation instance containing the given parameters.
+     * 
+     * @param roadType Type of the road (see {@link RoadType}).
+     * @param access Access restrictions for the road (see
+     * {@link AccessRestrictions}).
+     * @param isOneWay true if this road is a one way road, false otherwise.
+     * @param maxSpeed Maximum speed for the road (in kilometers-per-hour).
+     * @param name Name of the road.
+     */
     public RoadInformation(RoadType roadType, AccessRestrictions access, boolean isOneWay,
             int maxSpeed, String name) {
         this.type = roadType;
@@ -55,7 +68,7 @@ public class RoadInformation {
     }
 
     /**
-     * @return true if this is a private road.
+     * @return Access restrictions for this road.
      */
     public AccessRestrictions getAccessRestrictions() {
         return this.access;
@@ -69,14 +82,14 @@ public class RoadInformation {
     }
 
     /**
-     * @return true if this is a one-way road.
+     * @return true if the road is a one-way road.
      */
     public boolean isOneWay() {
         return oneway;
     }
 
     /**
-     * @return Maximum speed for this road (in kmph).
+     * @return Maximum speed for this road (in kilometers-per-hour).
      */
     public int getMaximumSpeed() {
         return maxSpeed;
@@ -89,10 +102,6 @@ public class RoadInformation {
         return name;
     }
 
-    /*
-     * (non-Javadoc)
-     * @see java.lang.Object#toString()
-     */
     @Override
     public String toString() {
         String typeAsString = "road";
diff --git a/src/main/org/insa/graph/io/BinaryGraphReaderInsa2018.java b/src/main/org/insa/graph/io/BinaryGraphReaderInsa2018.java
index eb3eea5..999f224 100644
--- a/src/main/org/insa/graph/io/BinaryGraphReaderInsa2018.java
+++ b/src/main/org/insa/graph/io/BinaryGraphReaderInsa2018.java
@@ -8,10 +8,9 @@ import java.util.EnumMap;
 import org.insa.graph.AccessRestrictions;
 import org.insa.graph.AccessRestrictions.AccessMode;
 import org.insa.graph.AccessRestrictions.AccessRestriction;
-import org.insa.graph.ArcBackward;
-import org.insa.graph.ArcForward;
+import org.insa.graph.Arc;
 import org.insa.graph.Graph;
-import org.insa.graph.GraphInformation;
+import org.insa.graph.GraphStatistics;
 import org.insa.graph.Node;
 import org.insa.graph.Point;
 import org.insa.graph.RoadInformation;
@@ -41,7 +40,7 @@ public class BinaryGraphReaderInsa2018 extends BinaryReader implements GraphRead
         // the order correspond to the 4 bits value (i.e. FORBIDDEN is 0 or PRIVATE is
         // 2) - UKNOWN is not included because value above 6 (FORESTRY) are all
         // considered unknown.
-        final AccessRestriction[] allRestrictions = new AccessRestriction[] {
+        final AccessRestriction[] allRestrictions = new AccessRestriction[]{
                 AccessRestriction.FORBIDDEN, AccessRestriction.ALLOWED, AccessRestriction.PRIVATE,
                 AccessRestriction.DESTINATION, AccessRestriction.DELIVERY,
                 AccessRestriction.CUSTOMERS, AccessRestriction.FORESTRY };
@@ -49,7 +48,7 @@ public class BinaryGraphReaderInsa2018 extends BinaryReader implements GraphRead
         // The order of values inside this array is VERY IMPORTANT: The order is such
         // that each 4-bits group of the long value is processed in the correct order,
         // i.e. FOOT is processed first (4 lowest bits), and so on.
-        final AccessMode[] allModes = new AccessMode[] { AccessMode.FOOT, null, AccessMode.BICYCLE,
+        final AccessMode[] allModes = new AccessMode[]{ AccessMode.FOOT, null, AccessMode.BICYCLE,
                 AccessMode.SMALL_MOTORCYCLE, AccessMode.AGRICULTURAL, AccessMode.MOTORCYCLE,
                 AccessMode.MOTORCAR, AccessMode.HEAVY_GOODS, null, AccessMode.PUBLIC_TRANSPORT };
 
@@ -240,16 +239,7 @@ public class BinaryGraphReaderInsa2018 extends BinaryReader implements GraphRead
                 Node dest = nodes.get(destNode);
 
                 // Add successor to initial arc.
-                ArcForward arc = new ArcForward(orig, dest, length, info, points);
-
-                // And reverse arc if its a two-way road.
-                if (!info.isOneWay()) {
-                    // Add without segments.
-                    // ArrayList<Point> rPoints = new ArrayList<Point>(points);
-                    // Collections.reverse(rPoints);
-                    // new Arc(dest, orig, length, info, null);
-                    new ArcBackward(arc);
-                }
+                Arc arc = Node.linkNodes(orig, dest, length, info, points);
                 observers.forEach((observer) -> observer.notifyNewArcRead(arc));
             }
         }
@@ -261,7 +251,7 @@ public class BinaryGraphReaderInsa2018 extends BinaryReader implements GraphRead
 
         this.dis.close();
 
-        return new Graph(mapId, mapName, nodes, new GraphInformation(maxSpeed, maxLength));
+        return new Graph(mapId, mapName, nodes, new GraphStatistics(maxSpeed, maxLength));
     }
 
     /**
diff --git a/src/main/org/insa/graphics/drawing/components/BasicDrawing.java b/src/main/org/insa/graphics/drawing/components/BasicDrawing.java
index ccffa77..b512699 100644
--- a/src/main/org/insa/graphics/drawing/components/BasicDrawing.java
+++ b/src/main/org/insa/graphics/drawing/components/BasicDrawing.java
@@ -22,7 +22,6 @@ import java.util.List;
 import javax.swing.JPanel;
 
 import org.insa.graph.Arc;
-import org.insa.graph.ArcForward;
 import org.insa.graph.Graph;
 import org.insa.graph.Node;
 import org.insa.graph.Path;
@@ -395,7 +394,6 @@ public class BasicDrawing extends JPanel implements Drawing {
 
     /*
      * (non-Javadoc)
-     * 
      * @see org.insa.graphics.drawing.Drawing#clear()
      */
     @Override
@@ -411,7 +409,6 @@ public class BasicDrawing extends JPanel implements Drawing {
 
     /*
      * (non-Javadoc)
-     * 
      * @see org.insa.graphics.drawing.Drawing#clearOverlays()
      */
     @Override
@@ -472,7 +469,6 @@ public class BasicDrawing extends JPanel implements Drawing {
 
     /*
      * (non-Javadoc)
-     * 
      * @see
      * org.insa.graphics.drawing.Drawing#addDrawingClickListener(org.insa.graphics.
      * drawing.DrawingClickListener)
@@ -484,7 +480,6 @@ public class BasicDrawing extends JPanel implements Drawing {
 
     /*
      * (non-Javadoc)
-     * 
      * @see org.insa.graphics.drawing.Drawing#removeDrawingClickListener(org.insa.
      * graphics.drawing.DrawingClickListener)
      */
@@ -528,9 +523,9 @@ public class BasicDrawing extends JPanel implements Drawing {
      * 
      * @param arc Arc to draw.
      * @param palette Palette to use to retrieve color and width for arc, or null to
-     *        use current settings.
+     * use current settings.
      */
-    protected void drawArc(ArcForward arc, GraphPalette palette, boolean repaint) {
+    protected void drawArc(Arc arc, GraphPalette palette, boolean repaint) {
         List<Point> pts = arc.getPoints();
         if (!pts.isEmpty()) {
             if (palette != null) {
@@ -645,8 +640,11 @@ public class BasicDrawing extends JPanel implements Drawing {
 
         for (Node node: graph.getNodes()) {
             for (Arc arc: node.getSuccessors()) {
-                if (arc instanceof ArcForward) { // draw only "true" arcs
-                    drawArc((ArcForward) arc, palette, false);
+                // Draw arcs only if there are one-way arcs or if origin is lower than
+                // destination, avoid drawing two-ways arc twice.
+                if (arc.getRoadInformation().isOneWay()
+                        || arc.getOrigin().compareTo(arc.getDestination()) < 0) {
+                    drawArc(arc, palette, false);
                 }
             }
             if (node.getId() % repaintModulo == 0) {