Calculating toll using dynamic assignment

For path selection, in the Vissim network, dynamic assignment takes link sequences without toll routes as well as link sequences with managed lanes facilities and toll routes into account (Defining a vehicle route of the type managed lane). This allows you to model, simulate and evaluate the following use cases, for example:

• Impact of toll route pricing on the surrounding traffic situation: How will demand on toll routes, toll-free routes and alternative routes develop if pricing is changed?
• Effects of a future change in demand: How will the capacity requirements for toll routes, toll-free routes and alternative routes change when demand changes?

Decision on toll route is based on a managed lanes routing decision

As with static routing decisions and routes, in dynamic assignment the vehicle decides which toll route to follow when it traverses a managed lanes routing decision. The decision is made based on the decision model and the toll pricing calculation model of the assigned managed lanes facility. (Defining managed lane facilities), (Defining decision model for managed lane facilities), (Defining toll pricing calculation models).

In dynamic assignment, the vehicle takes into account the managed lanes routing decision and its toll route or toll-free route, if the following conditions are met:

• The path search must consider the managed lane routing decision and the common destination section of the toll route and the toll-free route placed downstream. These objects must lie on a path. This path does not have to include the entire toll route.
• Toll routes and toll-free routes must traverse the same nodes which contain the Use for dynamic assignment attribute.

If at the manged lanes routing decision, the vehicle can neither select the toll route nor the toll-free route, it continues on the path assigned to it by dynamic assignment at the start of the journey.

Vissim combines edges and paths

After the dynamic assignment graph has been generated, Vissim combines edges, in particular for path selection and convergence definition, under the following conditions:

• The edges lie within a node or between two nodes.
• The toll-free route runs over one edge and the toll route runs over the other edge.

For each of the combined edges, Vissim aggregates the volume and travel time for the shortest combined edge. This edge then represents the combined edges. The Edges list shows all edges. It also includes combined edges.

For path searches and path selection, Vissim combines the two routes that run along the toll route and toll-free route of a managed lanes routing decision. This path represents the two combined paths. The represented path data is displayed in the *.weg path file (Files of dynamic assignment).

Modeling of managed lanes routing decisions and toll routes

When modeling the above-mentioned use cases, pay particular attention to the effects of managed lanes routing decisions and the notes on modeling (Mode of action of routing decisions of the type Managed Lanes).

Closed edges, connectors and routes

• The vehicle does not take into account a managed lanes routing decision positioned on a closed edge.
• If a connector is closed for all vehicle classes, there is no edge traversing the connector that can be taken into account for path search. If a toll route leads via a closed connector, vehicles will not be able to use the toll route.
• If a connector is closed for some vehicle classes only, an edge leads via the connector. If this edge is the shortest of the combined edges, the edge is considered for path search.
• A managed lanes routing decision is not taken into account if a route is closed and the following applies for the toll objects on the route (Defining a vehicle route of the type closure):
• Managed lanes routing decision and destination section are on the closed route. The closed route corresponds to the toll route or toll-free route between the managed lanes routing decision and the destination section.
• The managed lanes routing decision lies on the closed route. The closed route corresponds to the toll route or toll-free route from the managed lanes routing decision on.
• The common destination section of the toll-free route and the toll route lies on the closed route. The closed route corresponds to the toll route or toll-free route up until the destination section.
• The entire closed route lies on a toll route or on a toll-free route.

Changes to toll objects delete dynamic assignment graph

After a managed lanes routing decision or a toll route has been changed, you must recreate the dynamic assignment graph (Building an Abstract Network Graph), (Generating a node-edge graph).

Dealing with detours

A toll route cannot be a detour of its toll-free route, and vice versa. Even if in the parameters of dynamic assignment, on the Choice tab, Avoid long detours: is selected, the program will not consider using a toll route as a detour for a toll-free route or vice versa.

Effect of dynamic routing decisions

Dynamic routing decisions also affect vehicles driving on a toll route. The vehicle can leave the toll route.

Effect of parking routing decisions

Parking routing decisions also affect vehicles driving on a toll route. The vehicle can leave the toll route and drive to the parking lot.