diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/CriticalPathCalculator.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/CriticalPathCalculator.java
index 6cf998dd8..b3ef281da 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/CriticalPathCalculator.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/CriticalPathCalculator.java
@@ -91,13 +91,11 @@ public class CriticalPathCalculator<T, D extends IDependency<T>> {
     }
 
     private InitialNode<T, D> createBeginningOfProjectNode() {
-        return new InitialNode<T, D>(new HashSet<T>(graph.getInitialTasks()),
-                graph);
+        return new InitialNode<T, D>(new HashSet<T>(graph.getInitialTasks()));
     }
 
     private LastNode<T, D> createEndOfProjectNode() {
-        return new LastNode<T, D>(new HashSet<T>(graph.getLatestTasks()),
- graph);
+        return new LastNode<T, D>(new HashSet<T>(graph.getLatestTasks()));
     }
 
     private Map<T, Node<T, D>> createGraphNodes() {
@@ -106,7 +104,8 @@ public class CriticalPathCalculator<T, D extends IDependency<T>> {
         for (T task : graph.getTasks()) {
             Node<T, D> node = new Node<T, D>(task, graph
                     .getIncomingTasksFor(task),
-                    graph.getOutgoingTasksFor(task), graph);
+                    graph.getOutgoingTasksFor(task), graph.getStartDate(task),
+                    graph.getEndDateFor(task));
             result.put(task, node);
         }
 
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/InitialNode.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/InitialNode.java
index 176c205ee..3cca95c2d 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/InitialNode.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/InitialNode.java
@@ -32,9 +32,8 @@ import org.zkoss.ganttz.data.IDependency;
  */
 public class InitialNode<T, D extends IDependency<T>> extends Node<T, D> {
 
-    public InitialNode(Set<? extends T> nextTasks,
-            ICriticalPathCalculable<T> graph) {
-        super(null, null, nextTasks, graph);
+    public InitialNode(Set<? extends T> nextTasks) {
+        super(null, null, nextTasks, null, null);
     }
 
 }
\ No newline at end of file
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/LastNode.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/LastNode.java
index 8eff8ebe5..328c023b4 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/LastNode.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/LastNode.java
@@ -31,9 +31,8 @@ import org.zkoss.ganttz.data.IDependency;
  */
 public class LastNode<T, D extends IDependency<T>> extends Node<T, D> {
 
-    public LastNode(Set<? extends T> previousTasks,
-            ICriticalPathCalculable<T> graph) {
-        super(null, previousTasks, null, graph);
+    public LastNode(Set<? extends T> previousTasks) {
+        super(null, previousTasks, null, null, null);
     }
 
     public void updateLatestValues() {
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/Node.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/Node.java
index 43e2fb0c5..d40222668 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/Node.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/Node.java
@@ -26,6 +26,7 @@ import java.util.Set;
 
 import org.joda.time.Days;
 import org.joda.time.LocalDate;
+import org.zkoss.ganttz.data.GanttDate;
 import org.zkoss.ganttz.data.IDependency;
 
 
@@ -46,12 +47,19 @@ public class Node<T, D extends IDependency<T>> {
     private Integer latestStart = null;
     private Integer latestFinish = null;
 
-    private ICriticalPathCalculable<T> graph;
+    private LocalDate beginDate = null;
+    private LocalDate endDate = null;
 
     public Node(T task, Set<? extends T> previousTasks,
-            Set<? extends T> nextTasks, ICriticalPathCalculable<T> graph) {
+            Set<? extends T> nextTasks, GanttDate startDate, GanttDate endDate) {
         this.task = task;
-        this.graph = graph;
+
+        if (startDate != null) {
+            this.beginDate = new LocalDate(startDate.toDayRoundedDate());
+        }
+        if (endDate != null) {
+            this.endDate = new LocalDate(endDate.toDayRoundedDate());
+        }
 
         this.earliestStart = 0;
         this.earliestFinish = getDuration();
@@ -111,16 +119,9 @@ public class Node<T, D extends IDependency<T>> {
             return 0;
         }
 
-        LocalDate beginDate = new LocalDate(graph.getStartDate(task)
-                .toDayRoundedDate());
-        LocalDate endDate = getTaskEndDate();
         return Days.daysBetween(beginDate, endDate).getDays();
     }
 
-    private LocalDate getTaskEndDate() {
-        return new LocalDate(graph.getEndDateFor(task).toDayRoundedDate());
-    }
-
     @Override
     public String toString() {
         return "Task: " + getDuration() + " (" + earliestStart + ","