Tours and Trips

The PTV xTour service allows you to create tours to execute a set of orders. These created tours respect preexisting boundary conditions. Those boundary conditions incorporate a fleet of a finite capacity and size, restricted opening intervals of sites, driving times between the sites as well as service times at the sites.

A tour subdivides into trips. That is, a trip is a subsequence of a tour, and hence, a trip is a sequence of stops, possibly with a vehicle The term vehicle describes what is being routed or planned for. Vehicles are used in route calculation, distance matrix calculation and effectively also in tour planning. In route calculation, vehicle properties like overall size, weight and speed are in focus. In tour planning, it is vehicle properties like capacity and availability. Commonly a vehicle is motorized, like a truck - including its trailer or a car. However also a bike or even a pedestrian are included in this definition. location in the front and/or in the back, and rides between the locations, just like the tour. There is always at least one trip per tour, and a trip comprises at least one stop.

This page describes technical concepts which are necessary to understand the structure of the calculated tours, as well as parameters affecting this structure.

Cases for the start of a tour:

• vehicle start location followed by a depot stop
• vehicle start location followed by a customer stop
• first stop of the tour (either at a depot or a customer site)

A vehicle start location can be any type of location.

The first trip starts at the

• vehicle start location if a vehicle location is defined and the first stop is a customer.
• first stop if there is no vehicle location defined or if the first stop is at a depot.

The cases for the tour end are symmetrical to the described ones, i.e. the tour ends at its vehicle end location or at its last stop.

A trip ends whenever there are no more orders in execution after a delivery task at a depot. In this case the trip ends at this depot and the last stop of this trip is at this depot.

A trip also ends after a ride to a depot when there are no orders in execution. In this case the trip ends with an empty ride to this depot. The last stop of this trip however is at the previous site.

Cases between trips:

• delivery and pickup tasks at depot
• only delivery tasks at depot
• only pickup tasks at depot
• empty ride between trips

If both pickup and delivery tasks are performed at a depot, the delivery tasks form the last stop of their trip. The first stop of the next trip is formed by the pickup tasks at that depot.

If only tasks for one of the adjacent trips are performed at a depot, then there is no corresponding stop in the other trip as stops must have at least one task.

Empty rides that belong to no trip are depicted with gray dashed arrows. Empty rides within trips are depicted as colored dashed arrows.

Tour structures where a site is visited multiple times for loading or for unloading are undesired. To avoid such tour structures, xTour restricts the possible tour structures to certain loading sequences. The following is not allowed for valid loading sequences:

• A site is left although there is still load for it on the vehicle.
• A site is reached again although there is still load from it on the vehicle.

Show example...

Starting position and valid loading sequence if there are three transport orders:

The following changes would make the loading sequence above invalid (the violations are depicted with a black dashed arrow):

Another valid loading sequence:

Input:

• The vehicle starts and ends its tour at the same vehicle location which differs from the depot and customer sites.
• A transport order from Depot A to Customer 1.
• A transport order from Depot B to Customer 2.
• A transport order from Customer 3 to Depot A.
• Two transport orders from Depot B to Customers 4 and 5.

Output:

The tour begins at the vehicle start location. The empty ride to Depot A does not belong to any trip.

The goods of the first order are picked up at Depot A. Here, the first trip starts. The next stop is Depot B where the goods of the second order are picked up. The subsequent stops are for the deliveries of the goods on the vehicle, followed by a pick-up stop at Customer 3. The ride between Customer 2 and Customer 3 is an empty ride but the current trip cannot end here because neither Customer 2 nor Customer 3 is a depot, and only depots act as trip delimiters. The vehicle returns to Depot A to deliver the goods from Customer 3. Since the vehicle has arrived at a depot where the vehicle becomes empty, the first trip ends here.

The remaining orders are to be picked up at Depot B. Therefore, the vehicle heads towards Depot B. The empty ride between the depots is not a part of any trip, but only part of the tour.

The second trip starts with the pick-up stop at Depot B, followed by two delivery stops. Since there are no pick-up orders in the second trip, there is no reason to approach a depot after the delivery at Customer 5. Therefore, the vehicle heads towards the vehicle location. The empty ride between Customer 5 and the vehicle location is a part of the second trip because a trip can only end at a depot or at a vehicle end location. The second trip ends as soon as the vehicle arrives at its end location.

Graphic:

Input:

• The vehicle starts and ends its tour at the same vehicle location which differs from the depot and customer sites.
• Two transport orders between customers. One from customer 1 to customer 2 and one from customer 2 to customer 4.
• Two transport orders from customers 3 and 6 to the depot.
• Three transport orders from the depot to customers 5, 6 and 7

Output:

The tour starts at the vehicle location just like the first trip because the first site along the tour is a customer site. The goods from Customer 1 are delivered to Customer 2. The goods from Customer 2 are delivered to Customer 4. In between, goods are picked up at Customer 3 that need to be returned to the depot. The first trip ends after unloading these goods at Depot A.

Immediately after that, the second trip starts with the loading of the goods for customers 5,6 and 7. At Customer 6, goods are picked up to be returned to the depot. As soon as these goods are delivered at Depot A, the second trip ends.

The empty ride from the depot to the vehicle location is not a part of any trip but only part of the tour.

Graphic:

This setting ensures that each vehicle is assigned to only one trip at maximum. Further, the orders referring to different depots are executed by different vehicles.

Orders referring to different depots are strictly separated by the vehicles, which are used to process them. Vehicles are allowed to process multiple consecutive trips.

Vehicles are restricted to one single trip each at maximum. However, multiple different depots are allowed to be served within the tour.

There are no restrictions on the amount of trips within the tour, or depots to be served by one vehicle.

Additionaly, the resulting tour structure is affected by the type of the given sites. Depot sites are subject to a tighter restrictions compared to customer sites. A delivery task at a depot site cannot be followed by any other task than a depot site delivery within the same trip. Otherwise the current trip ends. So, when modelling for example a logistic hub, which is approached multiple times within a trip, using a customer site instead of a depot site would be a feasible solution.