Particularly in urban areas a large amount of traffic is caused as a result of economic activities. These include various trip purposes, such as the delivery and distribution of goods, the supply of construction materials and disposal of construction waste or the provision of services, e.g. through craftsmen or nursing services. Tour-based freight transport largely differs from passenger transport in terms of its characteristics and spatial and temporal trip distribution. Instead of groups of people that are homogeneous in their behavior, we are dealing with sectors. These are interrelated and generate and process orders. Orders are delivered in trips. Here a different numbers of similar activities are combined to a trip, while in passenger transport different activity chains are formed during the day. Depending on the sector and the delivery concept or vehicle type used, trips are marked by different characteristics. While in some sectors (e.g. parcel service) trips are highly optimized to make sure the individual destinations are in proximity to each other, in other sectors trips are controlled via external requirements, and the spatial distribution of the destinations is less important. In other sectors, trips are e.g. formed based on the vehicle type. Larger vehicles are used to deliver to less destinations, covering a longer distance than smaller vehicles. This means a combination of sector requirements and delivery concept (i.e. vehicle type) represents the demand stratum level relevant for calculations. As a result of this structure, mode choice is not part of the model, but is specified in advance via the input parameters.
For modeling tour-based freight, there is a separate demand model available that includes the corresponding demand objects and procedures. Key elements of the model are based on the WIVER model (Sonntag, 1995), jointly developed by IVU and PTV in the 90s and applied in numerous transport models. This model allows you to model origin and destination traffic resulting from orders as well as interrelations between different industries. On this basis, you can then model how these orders are delivered in trips. The model provides the necessary data structures for modeling sector requirements and delivery concepts or vehicle types. Trip matrices of tour-based freight are calculated in two procedures. In the first step, generation and distribution, order volumes and their spatial distribution are determined. In the second step, trip generation, trip matrices are derived from the data obtained through step 1.
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Note: In the directory C:\Users\Public\Documents\PTV Vision\PTV Visum 2021/Examples, you can find an example of use on this topic. The Demand Freight example shows the structure of a tour-based freight demand model and how some parameters impact the calculation of demand. |
