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Element |
Description |
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Use current assignment result as initial solution |
Notes This option is recommended in the case of modified demand (e.g. due to 'Read matrix additionally' or matrix editing in the matrix editor). First, the former assignment result is scaled according to the new demand and then the assignment continues to calculate the new result. Usually, this requires fewer iterations than a complete recalculation. In this way, a lot of computation time can be saved in models with feedback from the assignment calculation to the demand calculation. Multiple network modifications and repeated use of this option result in a different assignment result than a new assignment without this option would have resulted in, since there are numerous states which satisfy Wardrop's first principle of the equilibrium procedure.
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| Use classical convergence criteria |
If this option is selected, the classical criteria described below are taken into account. |
| Use extended convergence criteria |
If the option is selected, you can define additional termination conditions in addition to the classic convergence criteria. These are described further down in the table in the Extended section. The extended criteria can be used to check which links and turns show greater deviations in volume and/or impedance between iterations, and a minimum percentage of converged links and turns can be used as an additional convergence criterion (Fundamentals: Convergence criteria of assignment quality). Note The shares of network objects based on the extended convergence criteria are always calculated, regardless of the option set, and output in the PrT assignment quality data list. |
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Termination conditions |
Maximum number of iterations Specify the maximum number of iterations after which the procedure ends if no convergence occurs. Maximum gap Measure of the difference between the current loaded state and the balanced state. The procedure terminates as soon as the value falls below. |
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Classical |
Convergence statistics The settings you make here only take effect for the output of the shares in the PrT assignment quality data list. Relative difference between previous and current iteration Enter the desired value for the relative difference for link volume/impedance and turn volume/impedance for comparing results of successive iterations. The input values for links apply to the output of the shares of the connectors. Ignore links and turns with a volume < Network objects whose volume is beneath the defined threshold are not taken into account. |
| Extended |
Relative difference between previous and current iteration For the comparison of results of successive iterations, a value for the relative difference must be defined for each convergence criterion. The calculation of the share of objects is based on the links or turns/main turns open in the network. Link volume <=/Link impedance <= Enter a numerical value and define the share of links in percent that meet the respective condition. Turn volume <=/Turn impedance <= Enter a numerical value and define the share of turns in percent that meet the respective condition. Note The input value for the share applies to both the turn and the main turn together. Ignore links and turns with a volume < Network objects whose volume is beneath the defined threshold are not taken into account. Consider only active links and turns If the option is selected, the termination is based on the relative differences for the active links, turns, and main turns. Number of iterations taken into account for convergence Enter the number of iterations to be taken into account. Notes The assignment is considered converged if the condition for link volume or link impedance, the condition for turn volume or turn impedance, and the condition for the gap are fulfilled. Besides, these criteria must be fulfilled in the specified number of consecutive iterations. The convergence attributes of the assignment are always stored at links, turns, main turns, and connectors. |
If this option is checked, the assignment will use existing paths and volumes of the previous assignment as an initial solution.
If the option is not selected, an all-or-nothing assignment is calculated as initial solution. 
