Modeling vehicle routes, partial vehicle routes, and routing decisions

A route is a fixed sequence of links and connectors:

• A route starts with a routing decision (From Section default color is purple)
• It ends at a so-called To Section (default color is turquoise).

A routing decision point normally leads to several "to sections". Thereby the individual routes branch out from the routing decision point to the individual "to sections".

A route may have any length. You can use a route to simply display a turning movement at a single junction or to connect multiple nodes throughout your network. In many cases, it is useful to deploy routes throughout the Vissim network.

A routing decision only applies to vehicles that have been assigned a vehicle class and that are without any routing information. A vehicle already on a route may only accept new routing information after it has passed the "to section", i.e. destination, of its route. However, this does not include vehicles on partial routes, PT partial routes and parking lot routes.

Types of routing decisions and routes

The following types can be distinguished:

Static routing decisions and routes

Guides vehicles from a start section (purple) to one of the defined destination sections (turquoise) of the vehicle routes. In this case, the Route choice method attribute allows you to select the basis on which vehicles are distributed across vehicle routes:

• Static: Based on the static share per vehicle route that you define in the Relative volume attribute of the vehicle route (Attributes of static vehicle routes).
• Formula: Based on a user-defined formula (formula route). The formula is used to calculate the share of vehicles for the vehicle route depending on the attributes and attribute values of the vehicles [VEHICLE], for example [VEHICLE\SPEED], or the vehicle route [VEHICLEROUTESTATIC] (Attributes of static vehicle routes). For example, you can use the route choice method Formula to distribute taxis across several queues.

Static routing decisions do not apply to PT vehicles (Modeling short-range public transportation), (Defining PT lines).

Partial routes and partial PT routes

• Partial route: Serves for local distribution of vehicles. Defines a section of one or multiple static routes. For this section, the routes of all relevant vehicles are newly assigned according to the partial route shares of this section. After leaving the partial route, vehicles continue with their original route.

Partial routing decisions do not apply to PT vehicles.

• Partial PT route: Defines a section of one or multiple static routes. For this section, the routes of all relevant vehicles of the PT lines selected are newly assigned according to the partial route shares of this section. Use the Route choice method to specify the basis on which vehicles are distributed across the partial route share of the vehicle route (Attributes of partial vehicle routes). After driving on the partial route, vehicles of PT lines continue driving on their original route.

Similar to when defining PT line stops, you can define PT stops for your PT partial route, including attributes for dwell time (Modeling PT lines):

As long as a vehicle has not completed its original line route, its Departure offset is treated like an offset at a stop of the original route (Attributes of PT lines). Once the PT vehicle has passed the "to section" of its original line route, the Departure offset specified for a PT partial route stop is interpreted as relative to the simulation time when the vehicle passes the respective routing decision point.

Parking routes

Only for parking lots of the type Real parking spaces: Defines a routing decision point used to automatically generate routes leading to each of the respective parking lots and back to the network. You select parking lots instead of destination sections (Defining parking routes). When modeling a parking route, avoid self-intersecting. Using Check network, Vissim identifies parking routes that intersect and lead to a parking lot that can be reverse parked into or reverse parked out of. For these parking routes Vissim discards the existing path and finds the shortest path from the parking routing decision to the parking lot. In doing so, the parking route for reverse parking continues to follow the original connector for reverse parking into the parking lot.

If the vehicle drives over a parking routing decision, Vissim determines for each parking route of this routing decision the free parking spaces in the destination parking lot as well as their attraction. The attraction of a parking space results from the attraction of the first and last parking space of the parking lot. Thus, all parking routes to a parking space have the same attraction. Thus, parking options result from parking route, parking space and its attraction. Park options whose Parking direction attribute has the value Invalid are discarded. From the set of parking options with the highest attraction, Vissim selects the parking space equally distributed and then Vissim considers the relative volume of the parking route to this parking space.

Positioning parking routing decisions of car parks

When you create a car park and select the attribute value Add new objects for the attributes Parking routing decision main direction and Parking routing decision opposite direction, Vissim places a new routing decision of the type Parking lot for each direction of the drive aisle. You must move it to the desired upstream position.

If you then want to create another car park and assign an existing parking routing decision to it, select the desired parking routing decision for the attributes Parking routing decision main direction and Parking routing decision opposite direction in the Create car park window. Make sure that this parking routing decision is placed upstream at the desired position before creating the other car parks, selecting this parking routing decision each time. This position can also be another drive aisle.

If you want to duplicate a parking routing decision to assign it to a car park you want to create, make sure you first duplicate the desired parking routing decision, then create the new car park, and then move the duplicate parking routing decision.

Routes for managed lanes

Routes vehicles via two parallel routes (managed lanes), from the start section to a destination section (Defining a vehicle route of the type managed lane). For a routing decision of the type Managed Lanes, you must define a managed lanes facility with a toll pricing model and decision model. Consequently, the following is taken into account:

• occupation rate of vehicles with one, two or three or more persons
• the time of day
• the current traffic situation, including time savings and average speed

If the current Managed Lanes route is replaced with a new route at such a Managed Lanes routing decision, it is possible that the travel times for previously begun Managed Lanes routes continue to be counted until the vehicle passes its chosen destination.

The following conditions must be fulfilled for this to occur:

• The vehicle maintains its decision for or against the toll.
• The old destination is located on the new route or the new destination is on the old route.

If the conditions are not fulfilled, the total travel time for the old route is proportionally estimated when more than 75% of the length has been completed.

Like all other routing decisions types, only the vehicles of the selected vehicle classes will be taken into account. Vehicles of a type, in which the classes are not selected here, use neither the toll route nor the toll-free route. Thus, for example, HGVs can be excluded. Note the effects of routing decisions of the type managed lanes facilities (Mode of action of routing decisions of the type Managed Lanes).

Routing decisions and routes for dynamic assignment

• Dynamic: Defines a routing decision point, at which traffic is re-routed. For the route, you must have defined a condition or strategy (Defining dynamic routing decisions), (Modeling parking lots and zones).
• Closure: Defines a route as a link sequence that will not be available for dynamic assignment (Influencing path search and path choice). You need not assign time intervals to routes of the type Closure. You do not have to enter a relative volume.