The construction of public transport lines requires a base model that reflects both the infrastructure and the desired demand for public transport.
Infrastructure
The link network that can be used by public transport is part of the infrastructure. The procedure generates the line routes in this link network and takes over the run times. If you want to create a line concept for a public transport system, the trafficability and link run time of the links for this transport system must be ensured. Prohibited turns, especially U-turns, must also be modeled correctly.
Links that are permitted for a PuT Walk transport system are also used as walk links by public transport passengers. This may mean that no regular line routes are formed along these links. Links should only be opened up for PuT Walk for specific, selected transfer relations. The assignment used in the procedure takes into account the settings for the maximum walk time and for searching within stop points from the general procedure parameters.
The stop points are another part of the infrastructure. These must also already exist in the model and be permissible for the relevant transportation systems. Stop points at which a line can begin or end must be identified using any attribute. These terminal stop points form the start and end points of the generated line routes later in the procedure. To calculate the route run time, the stop time must be specified for all stop points.
The frequency of operation can be controlled via any attributes at the stop points. For example, specifications from the local transport plan can be implemented in order to specify a minimum number of services, although the stored demand would not justify this. On the other hand, it may make sense to limit the maximum number of vehicle journeys at a stop point for capacity reasons.
Demand
Taking demand into account is crucial for the creation and evaluation of the line concepts. It should be noted that the current demand for public transport should not be used, as this results in a feedback to the existing supply, because the current demand for public transport is particularly strong on those relations on which a good supply is currently operated. A lack of current demand may therefore be due to inadequate public transport supply. People who reach their destination on foot should not be included in the demand. They increase the calculation time and in the demand model they would become pedestrians again. The demand taken into account should therefore be a share of the total demand minus non-motorized private transport. By selecting the share, it is thus possible to create a transport supply for a given modal split.
The demand must be aggregated and connected according to the existing zone structure in the network. The time reference of the demand must correspond to the assignment time period.
The selection of the time range defines the generated supply. Demand for the peak hour will generate supply for the peak hour. As a consistent route is desirable for passengers, the line construction and headway calculation should be based on demand for the main operating hours (e.g. 5 AM to 7 PM). To adjust the supply on Sundays and public holidays, only the calculation step Calculate headways on the corresponding demand is carried out in a second step in the procedure.
Taking existing transport supply into account
The line proposal procedure can optionally take into account the existing transport supply. Supply planning is always carried out from the perspective of the network context. This means that the transport supply offered by other operators that is available to passengers must also be taken into account when preparing the supply. The supply of long-distance transport, for example, is not changed in urban supply planning, but must be taken into account in the network context. A multi-stage planning process can be carried out as part of urban planning. First, for example, the tram supply is planned with the corresponding demand. In the second step, the tram lines are fixed in order to realize the planning of the bus as a feeder route.
Existing lines are regarded as fixed lines. You can choose whether only their route course is fixed or whether their specified headway is also unchangeable. The supply of existing lines must be modeled in a simplified way. Each line carries the headway information and may only have one line route and one time profile per direction. This modeling is consistent with the lines generated in the procedure.
Lines in the network that are not specified as fixed are deleted from the procedure.
Another way of taking existing transport supply into account is the competition with other modes of transport. If the travel time for the ideal public transport connection is much higher than in another mode, this relation is optionally ignored in the line construction. Examples of this are non-motorized private transport (walking / cycling) on short distances or relations along expressways for motorized private transport. The quality of the competing supply is indicated as a travel time matrix.
Checking the network
You can perform a series of checks to ensure the quality of the network model data:
- Travel times and calculated speeds on links. An error is displayed if there are links with a travel time of 0 s. If the calculated speed is above 100 km/h, warnings are issued.
- High share of open U-turns for public transport. From 5%, a warning is issued for checking.
- Share of open links for the PuT Walk transport system. From 10%, a warning is issued for checking.
- Value of the parameter for the maximum walk time is set. A warning is issued after 30 minutes.
- If there is no demand in the specified assignment time period, but headways are to be calculated, an error is displayed.
- If there is no simplified modeling of the fixed lines, an error is displayed.
