title: Add/remove vehicles in SUMO via TraCI at runtime
body: <p>I know that traci.vehicle API has an add and a remove function which is just <strong>traci vehicle remove or traci vehicle add</strong>. I am using SUMO on Windows. I have the network, the routes and a fixed number of 37000 vehicles in the network. I started my simulation in python and tried to remove a vehicle  as follows when simulation is running:</p>
  
  <pre><code>import traci 
  traci.start(sumoCmd)
  stepz = 0
  while traci.simulation.getMinExpectedNumber() &gt; 0 and stepz &lt; 7000:
     traci.simulationStep()
     traci.vehicle.remove("2773")
  traci.close()
  </code></pre>
  
  <p>When I run this I get this error message:</p>
  
  <blockquote>
    <p>Traceback (most recent call last):
    File "", line 9, in 
        traci.vehicle.remove("2773")</p>
    
    <p>File "C:\Program Files (x86)\Eclipse\Sumo\tools\traci_vehicle.py", line 1579, in remove
        tc.CMD_SET_VEHICLE_VARIABLE, tc.REMOVE, vehID, reason)</p>
    
    <p>File "C:\Program Files (x86)\Eclipse\Sumo\tools\traci\connection.py", line 149, in _sendByteCmd
        self._sendExact()
      File "C:\Program Files (x86)\Eclipse\Sumo\tools\traci\connection.py", line 112, in _sendExact
        raise TraCIException(err, prefix[1], _RESULTS[prefix[2]])
      TraCIException: Vehicle '2773' is not known.</p>
  </blockquote>
  
  <p>"2773" is one of the vehicle's ID I got from my <strong>mytrip.trips.xml</strong> file. I don't know what is wrong with this piece of code and how to fix it. I also would like to know how should I find the <strong>RouteID</strong> to add a vehicle.
  Any help will be highly appreciated. </p>