diff -N LCIOFilterDriver.java
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ LCIOFilterDriver.java	6 Mar 2013 03:10:22 -0000	1.1
@@ -0,0 +1,92 @@

+/*
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package org.lcsim.hps.util;
+import java.io.IOException;
+import org.lcsim.event.EventHeader;
+import org.lcsim.event.Track;
+import org.lcsim.util.Driver;
+import org.lcsim.util.lcio.LCIOWriter;
+
+/**
+ *
+ * @author phansson
+ */
+public abstract class LCIOFilterDriver extends Driver {
+    protected String outputFile;
+    protected LCIOWriter writer;
+    protected boolean debug = false;
+    
+    public LCIOFilterDriver() {        
+    }
+    
+    public void setOutputFilePath(String output) {
+        this.outputFile = output;
+    }
+    
+    public void setDebug(boolean debug) {
+        this.debug = debug;
+    }
+    
+    abstract boolean eventFilter(EventHeader event);
+
+    private void setupWriter() {
+        // Cleanup existing writer.
+        if (writer != null) {
+            try {
+                writer.flush();
+                writer.close();
+                writer = null;
+            } catch (IOException x) {
+                System.err.println(x.getMessage());
+            }
+        }
+
+        // Setup new writer.
+        try {
+            writer = new LCIOWriter(outputFile);
+        } catch (IOException x) {
+            throw new RuntimeException("Error creating writer", x);
+        }
+
+
+        try {
+            writer.reOpen();
+        } catch (IOException x) {
+            throw new RuntimeException("Error rewinding LCIO file", x);
+        }
+    }
+
+    protected void startOfData() {
+        setupWriter();
+    }
+
+    protected void endOfData() {
+        try {
+            writer.close();
+        } catch (IOException x) {
+            throw new RuntimeException("Error rewinding LCIO file", x);
+        }
+    }
+
+    protected void process(EventHeader event) {
+
+        if(eventFilter(event)) {
+            try {
+                writer.write(event);
+            } catch (IOException x) {
+                throw new RuntimeException("Error writing LCIO file", x);
+            }
+        }
+    }
+
+    protected void suspend() {
+        try {
+            writer.flush();
+        } catch (IOException x) {
+            throw new RuntimeException("Error flushing LCIO file", x);
+        }
+    }
+    
+}

diff -N TwoTrackFilterDriver.java
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ TwoTrackFilterDriver.java	6 Mar 2013 03:10:22 -0000	1.1
@@ -0,0 +1,54 @@

+/*
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package org.lcsim.hps.util;
+
+import org.lcsim.hps.util.LCIOFilterDriver;
+import java.io.IOException;
+import org.lcsim.event.EventHeader;
+import org.lcsim.event.Track;
+import org.lcsim.util.Driver;
+
+/**
+ *
+ * @author phansson
+ */
+public class TwoTrackFilterDriver extends LCIOFilterDriver {
+    private String trackCollectionName = "MatchedTracks";
+    
+    public TwoTrackFilterDriver() {
+    }
+    
+    public void setTrackCollectionNamePath(String trackCollection) {
+        this.trackCollectionName = trackCollection;
+    }
+    
+    @Override
+    boolean eventFilter(EventHeader event) {
+        boolean pass = false;
+        
+        if(!event.hasCollection(Track.class, trackCollectionName)) {
+            throw new RuntimeException("Error, event doesn't have the track collection");
+        }
+        
+        if(this.debug) {
+            System.out.printf("%s: %d tracks in this event\n",this.getClass().getSimpleName(),event.get(Track.class, trackCollectionName).size());
+        }
+        
+        if (event.get(Track.class, trackCollectionName).size()>1) {
+            try {
+                if(this.debug) {
+                    System.out.printf("%s: write event %d \n",this.getClass().getSimpleName(),event.getEventNumber());
+                }
+                writer.write(event);
+            } catch (IOException x) {
+                throw new RuntimeException("Error writing LCIO file", x);
+            }
+        }
+
+        
+        return pass;
+    }
+    
+}