• Rerouter

Rerouter

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Rerouter#

Rerouter changes the route of a vehicle as soon as the vehicle moves onto a specified edge.

A rerouter is set into the simulated network by adding the following declaration line to an additional-file: <rerouter id="<REROUTER_ID>" edges="<EDGE_ID>[;<EDGE_ID>]*" file="<DEFINITION_FILE>" [probability="<PROBABILITY>"]/>. Rerouter may be placed on several edges, at least one edge is necessary. Furthermore, it is possible to define the probability for rerouting a vehicle by giving a number between 0 (none) and 1 (all) already within the definition. The declaration values are:

Attribute Name	Value Type	Description
id	id (string)	The id of of the rerouter
edges	float	An edge id or a list of edge ids where vehicles shall be rerouted
file	float	The path to the definition file (alternatively, the intervals may defined as children of the rerouter)
probability	float	The probability for vehicle rerouting (0-1), default 1
timeThreshold	time (s)	minimum accumulated waiting time before the rerouter takes effect (default 0 applies always)
vTypes	stringList	Space-separated list of vType IDs for which this rerouter should apply (default "" applies to all)
off	bool	Whether the router should be inactive initially (and switched on in the gui), default:false

A rerouter may work in several different ways. Within a time period you may close an edge, or assign new destinations or predefined routes to vehicles. The next sections will describe these actions in detail.

Definition styles#

There are two styles in which to declare rerouters.

everything in one file#

The additional-file looks like this:

<additional>
   <rerouter id="<REROUTER_ID>" edges="<EDGE_ID>[;<EDGE_ID>]*" [probability="<PROBABILITY>"]>
      <interval begin="<BEGIN_TIME>" end="<END_TIME>">
         ... action description ...
      </interval>

      ... further intervals ...
   </rerouter>

   ... further rerouters ...
</additional>

definitions in a separate file#

The additional-file looks like this:

<additional>   
   <rerouter id="<REROUTER_ID>" edges="<EDGE_ID>[;<EDGE_ID>]*" [probability="<PROBABILITY>"]>
     <include href="definitions.xml"/>      
   </rerouter>

   ... further rerouters ...
</additional>

And the file definitions.xml (which describes the actions over time) looks like this:

   <interval begin="<BEGIN_TIME>" end="<END_TIME>">
      ... action description ...
   </interval>

   ... further intervals ...

Note, that the definition file has no root-level element

All the following examples use the everything-in-one-file-syntax.

Closing a Street#

A "closingReroute" forces the rerouter to close the edge <EDGE_ID>. Vehicles which normally would pass this edge will get a new route as soon as they reach one of the edges given in the edges-attribute of the rerouter's declaration. The algorithm for selecting a new route is the same as described at #Assigning_a_new_Destination with the additional constraint that closed edges must be avoided. A closingReroute definition may look like this:

<rerouter>
   <interval begin="<BEGIN_TIME>" end="<END_TIME>">
      <closingReroute id="<EDGE_ID>"/>
   </interval>

   ... further intervals ...

</rerouter>

The attributes used within such definitions are:

Attribute Name	Value Type	Description
id	id (string)	The id of the closed edge; the id must be the id of an edge within the network
allow	list of vehicle classes	The (optional) ' '-separated list of vehicle classes which are still allowed to drive on the closed edge. All others are forbidden.
disallow	list of vehicle classes	The (optional) ' '-separated list of vehicle classes which are forbidden from driving on the closed edge. All others are allowed.

When using a <closingReroute> without attributes allow and disallow, vehicles that cannot reach their destination by an alternative route simply continue on their old route and will effectively ignore the closing of the edges. When using either attribute allow or disallow (only one may be used in the same definition), vehicles which cannot change their route will stop in front of the closed edge until the defined interval ends. This may be used to simulate traffic jams, caused by spontaneous road closing.

Closing a Lane#

A "closingLaneReroute" forces the rerouter to close the lane <LANE_ID> by setting its permissions to authority (this can be customized). Vehicles that pass this route and which are equipped with a rerouting device may compute a new route as soon as they reach one of the edges given in the edges-attribute of the rerouter's declaration. A closingLaneReroute definition may look like this:

<rerouter>
   <interval begin="<BEGIN_TIME>" end="<END_TIME>">
      <closingLaneReroute id="<LANE_ID>"/>
   </interval>

   ... further intervals ...

</rerouter>

The attributes used within such definitions are:

Attribute Name	Value Type	Description
id	id (string)	The id of the closed lane; the id must be the id of a lane within the network
allow	list of vehicle classes	The (optional) ' '-separated list of vehicle classes which are still allowed to drive on the closed edge. All others are forbidden. (default authority)
disallow	list of vehicle classes	The (optional) ' '-separated list of vehicle classes which are forbidden from driving on the closed edge. All others are allowed. (This attribute may be used instead of allow for brevity if only a few classes shall be disallowed).

Reversible Lanes#

Two closingLaneReroute definitions may be used to simulate a reversible lane in the following way:

• Define two edges in reverse directions with at least 2 lanes each
• prohibit driving on one of the central lanes (disallow="all")
• and modify the edge geometry so that the central lanes occupy the same space.
  • by shifting geometry of both edges sideways (-1.6 for default lane width)
  • or by setting the geometry directly

To change their direction for a specific duration, the following rerouter may be used:

<rerouter id="example" edges="E1 -E1">
      <interval begin="7:0:0" end="8:30:0">
            <closingLaneReroute id="E1_1" allow="all"/>
            <closingLaneReroute id="-E1_1" disallow="all"/>
      </interval>

   </rerouter>

Alternatively to changing lane permissions with a rerouter, the traci functions traci.lane.setAllowed and setDisallowed may also be used.

Assigning a new Destination#

A "dest_prob_reroute" forces the rerouter to assign a new route to vehicles that pass one of the edges defined in the edges-attribute of the rerouter's declaration. A new route destination is used, defined by the name of a new destination in the according element:

<rerouter>
   <interval begin="<BEGIN_TIME>" end="<END_TIME>">
      <destProbReroute id="<EDGE_ID1>" probability="<PROBABILITY1>"/>
      <destProbReroute id="<EDGE_ID2>" probability="<PROBABILITY2>"/>
   </interval>

   ... further intervals ...

</rerouter>

The fastest route is computed automatically using the Dijkstra-algorithm and starting at the edge the vehicle is located at and ending at the new destination. The following travel times are considered for routing (the first applicable value is used):

• the current (smoothed) travel times in the network are used if the vehicle is equipped with a rerouting device
• subjective edge costs for the current vehicle if set viaTraCI command change edge travel time information
• edge weights loaded via the sumo option --weight-files
• travel times in the empty network

The attributes used within a dest_prob_reroute are:

Attribute Name	Value Type	Description
id	id (string)	The id of the new destination; the id must be the id of an edge within the network or one of the special values keepDestination, terminateRoute
probability	float (should be between 0 and 1)	The probability with which a vehicle will use the given edge as destination; the probabilities are automatically normalized to sum to 1

Special Destination Values#

• keepDestination: the vehicle continues on its current route
• terminateRoute: the vehicle immediately leaves the simulation and counts as arrived at its current position on the rerouter edge

Assigning a new Route#

A "route_prob_reroute" forces the rerouter to assign a new route to vehicles which pass one of the edges defined in the edges-attribute of the rerouter's declaration. In this case, the id of a complete route must be supplied instead of a new destination:

<rerouter>
   <interval begin="<BEGIN_TIME>" end="<END_TIME>">
      <routeProbReroute id="<ROUTE_ID1>" probability="<PROBABILITY1>"/>
      <routeProbReroute id="<ROUTE_ID2>" probability="<PROBABILITY2>"/>
   </interval>

   ... further intervals ...

</rerouter>

The attributes used within such definitions are:

Attribute Name	Value Type	Description
id	id (string)	The id of a new route to assign; the id must be the id of a previously loaded route
probability	float	The the probability with which a vehicle will use the given edge as destination; (default 1). The probabilities are automatically normalized for all entries

Repeated public transport routes#

If the new route assigned with the rerouter contains stops, the vehicle will use these stops. If the stops use attribute 'until' then the route should use attribute 'cycleTime' to shift the until-times by a set amount on each repeat.

Rerouting to an alternative Parking Area#

Vehicles that stop at a parking area may encounter the situation that the parking area has reached the limit of its capacity and does not permit parking.

In this case the vehicle either waits on the road until a parking space becomes available or it may reroute to an alternative parking area. For the latter behavior a parkingAreaReroute-definition must be specified. This rerouter definition defines a set of parking areas that may be mutually used as alternatives. Rerouting to another parking area is triggered in two cases:

• when a vehicle reaches a parkingArea and is unable to stop due to lack of capacity
• when a vehicle enters one of the rerouter-edges and the following conditions are all met:
  • it's current destination parkingArea is among the set of parkingAreaReroute definitions and has attribute visible="true"
  • it's current destination parkingArea is full

The definition looks like this:

   <rerouter id="myRerouter" edges="a b">
      <interval begin="0" end="2000">
         <parkingAreaReroute id="ParkAreaA"/>
         <parkingAreaReroute id="ParkAreaB"/>
      </interval>
   </rerouter>

The attributes used within such definitions are:

Attribute Name	Value Type	Description
id	id (string)	The id of an existing parking area
probability	float	The probability for each of the alternatives to be selected (default 1).
visible	bool	Whether occupancy of this parkingArea is known before reaching the parkingArea edge (this models line-of-sight as well as parking information systems).

Memory in parking search#

Parking search refers to the situation where a vehicle encounters an occupied parkingArea and has to pick among a list of alternative destinations without knowing their occupancy state. The vehicle has to iteratively drive to alternative destinations until a free parking space is found. ParkingAreas that were visited earlier (and occupied) might be reasonably visited again with the expectation that they have cleared up since the last visit. By default, vehicles will not visit an occupied parkingArea again for 600s. This can be modified with vehicle-param or vType-param as follows:

   <vehicle ...>
      <param key="parking.memory" value="300"/>
   </vehicle

Determining the alternative parking area#

The alternative parkingArea will be selected among all parking areas that are visible and have at least 1 free space according to the minimum weighted sum over a number of attributes. For invisible parkingAreas (attribute visible="false", the occupancy value is a taken as a random number from [0,capacity[ which means they are always among the set of alternatives even when full. Each attribute (i.e. occupancy, time, distance) is normalized to [0-1] with the maximum value of all candidate parkingAreas with positive remaining capacity) and inverted as necessary.

By default only the distance from the current vehicle position to the new parking area is considered. The following table describes the weighting factors that can be customized using generic parameters of the vehicle or its vType:

Parameter Name	Default value	Description	Inverse (Bigger is better)
parking.probability.weight	0	the influence of the probability attribute of the parkingAreaReroute	yes
parking.capacity.weight	0	The total capacity of the parking area	yes
parking.absfreespace.weight	0	The absolute number of free spaces	yes
parking.relfreespace.weight	0	The relative number of free spaces	yes
parking.distanceto.weight	1	The road distance to the parking area	no
parking.timeto.weight	0	The assumed travel time to the parking area	no
parking.distancefrom.weight	0	The road distance from the parking area to the vehicles destination	no
parking.timefrom.weight	0	The assumed travel time from the parking area to the vehicle destination	no

When 'parking.probability.weight' is set to a positive value, a random number between 0 and attribute 'probability' is drawn for each candidate parkingArea. This value is then normalized to then range [0,1] by dividing with the maximum probability value of all parkingAreaReroute elements. The negative normalized value is then multiplied with parking.probability.weight to enter into the candidate score.

Further parameters to affect parking behavior#

Parameter Name	Default value	Description
parking.anywhere	-1	permit using any free parkingArea along the way after doing unsuccessful parkingAreaReroute x times (-1 disables this behavior)
parking.frustration	100	increases the preference for visibly free parkingAreas over time (after x unsuccessfull parkingAreaReroutes, targets with unknown occupancy will assumed to be almost full)
parking.knowledge	0	Let driver "guess" the exact occupancy of invisible parkingAreas with probability x

Destination after rerouting#

Generally, vehicles that reroute to a new parking area will continue to their original destination after finishing the stop. In the special case where

1. the original route ended at the original parkingArea edge and
2. the arrivalPos was within [startPos, endPos] of the original parkingArea

then the new route will also end at the new parkingArea and the endPos of the new parkingArea will be set as new arrivalPos.

TraCI access to parkingSearch#

The current state of the parkingSearch can be accessed via calls to traci.vehicle.getParameter with the list permitted parameters given at TraCI/Vehicle_Value_Retrieval.

Vehicle Behavior when closing a street#

The interaction of vehicles with reroutes is complex and depends on many different factors. Below we give a description of each of the factors and then describe the behavior for each combination of factors. The following assumes vehicles that have an edge affected by <closingReroute .../> along their route (other vehicles are not affected directly).

1. closing style
   • a) hard closing: <closingReroute> uses attribute 'allow' or 'disallow' to prohibit the vehicle
   • b) soft closing: attribute is not used (edge use is discouraged but not forbidden)
2. alternatives
   • a) an alternative route exists
   • b) no alternative route exists
3. detour signage
   • a) an rerouter edge is encountered before the alternative route branches off
   • b) no rerouter edge is encountered before the alternative route branches off
4. vehicle style
   • a) vehicle defined with origin and destination where the affected edge is on the preferred route (i.e. <trip from="..." to="...">)
   • b) vehicle defined with fixed route
5. closing time versus departure time
   • a) vehicle departs after closing becomes active
   • b) vehicle departs before closing becomes active (closing occurs while en-route)

The following vehicle behaviors are possible:

• R: use an alternative route upon reaching the rerouter edge
• D: use an alternative route on departure
• I: ignore the closed edge and keep driving
• W: wait ahead of the closed edge until it reopens or time-to-teleport is reached (in this case teleport across the closed edge(s))
• E: generate an error

To following effects occur:

Hard closing#

• 1a-2a-3a-4a-5a: D
• 1a-2a-3a-4a-5b: R
• 1a-2a-3a-4b-5a: R
• 1a-2a-3a-4b-5b: R

• 1a-2a-3b-4a-5a: D
• 1a-2a-3b-4a-5b: W
• 1a-2a-3b-4b-5a: W
• 1a-2a-3b-4b-5b: W

• 1a-2b-3a-4a-5a: E (becomes W with --ignore-route-errors)
• 1a-2b-3a-4a-5b: W
• 1a-2b-3a-4b-5a: W
• 1a-2b-3a-4b-5b: W

• 1a-2b-3b-4a-5a: E (becomes W with --ignore-route-errors)
• 1a-2b-3b-4a-5b: W
• 1a-2b-3b-4b-5a: W
• 1a-2b-3b-4b-5b: W

Soft closing#

• 1b-2a-3a-4a-5a: R
• 1b-2a-3a-4a-5b: R
• 1b-2a-3a-4b-5a: R
• 1b-2a-3a-4b-5b: R

• 1b-2a-3b-4a-5a: I
• 1b-2a-3b-4a-5b: I
• 1b-2a-3b-4b-5a: I
• 1b-2a-3b-4b-5b: I

• 1b-2b-3a-4a-5a: I
• 1b-2b-3a-4a-5b: I
• 1b-2b-3a-4b-5a: I
• 1b-2b-3a-4b-5b: I

• 1b-2b-3b-4a-5a: I
• 1b-2b-3b-4a-5b: I
• 1b-2b-3b-4b-5a: I
• 1b-2b-3b-4b-5b: I

Departure on a closed edge#

When the departure edge for a vehicle is closed, vehicles will ignore this for 'soft' closing. For a 'hard' closing the simulation will raise an error. If --ignore-route-errors is set, the vehicle will be discarded with a warning.