Index: trunk/webapps/visualizer/index.html
===================================================================
--- trunk/webapps/visualizer/index.html	(revision 516)
+++ trunk/webapps/visualizer/index.html	(revision 528)
@@ -48,7 +48,8 @@
     <button id="cmsButton" class="unstyled-button"><img id="cmsBtnImg" src="images/btnReady_CMS.png"></button>-->
     <button id="vdsButton" class="unstyled-button"><img id="vdsBtnImg" src="images/btnDepressed_VDS.png"></button>
-    <p id="time">Time</p>
+    <p id="time">00:00:00</p>
     <button id="start" >Beginning</button>
     <button id="forward" >Next</button>
+	<button id="backward" >Back</button>
     <script  src="../common/js/fileutils.js"></script>
     <script  src="../common/js/revision_number.dat"></script>
@@ -95,4 +96,6 @@
     var filters = []; //array to hold markers for visualizer
     var times = []; //array to hold times of each traffic event
+    times[0] = "00:00:00";
+    var diff_arr = []; // array to hold difference in target markers
     var index = -1; //to index into above array
 
@@ -154,4 +157,8 @@
 
         updateVDSlayer();
+        setTimeout(function() {
+            buildDiff();
+            updateVDSlayer();
+        }, 3000);
 
         // Listen for zoom changes and move the vds dots so as to keep a nice