This variant uses a best-path search based on the Connection Scan Algorithm (reference). For a destination zone, this algorithm calculates the bi-criteria shortest paths from all origin zones for all possible departure times at once.
This search is bi-criteria because all the fastest connections are output for each permitted number of transfers. The two criteria considered are therefore transfer frequency and journey time. Connections with multiple transfers are only included in the trip set if they have a shorter journey time than the connections with fewer transfers.
The journey time is composed of the following path time segments:
- Access time [min]
- In-vehicle time [min],
- Transfer walk times:
- between two transfer stops [min]
- between nodes and stops [min]
- between node and node [min]
- Transfer wait time [min]
- Egress time [min]
If several connections of the same speed are found at a time, only a user-defined number of these paths are included in the resulting set of connections.
Equivalent connections are dominated in the shortest path search result (Dominance of equivalent connections). Two connections are considered equivalent when they differ in the selection of transfer stops but are the same in terms of departure time and sequence of the time profiles used.
Performing the shortest path search at each departure time leads to temporal independence of the results. This means that, in contrast to the Branch & Bound search, the shortest paths are found independently at other times. This leads to a robust path set in which there are only temporary changes when there are individual changes in supply.
As an alternative to the bi-criteria shortest path search, the shortest path with the least impedance is found for each origin zone and departure time. The definition of the impedance is given by a*RZ and b*UH, where the coefficients can be specified by the user. This option is useful if the path set is to be kept as small as possible and the perception of journey impedance is very homogeneous for the user group.
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Tips: To take advantage of the run time benefits of shortest path search, we advise:
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However, the shortest path search also works without these restrictions, but the run time decreases a lot if you follow the tips.
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Note: If you want to include vehicle or ride sharing services or vehicle capacities in the assignment, it is not possible to use the shortest path search. |
