Parameters of Equilibrium assignment LUCE

Equilibrium assignment LUCE: Basis tab

On this tab, enter the basic parameters for the procedure.

Element	Description
Use current assignment result as initial solution	If this option is checked, the assignment will use existing paths and volumes of the previous assignment as initial solution. Notes This option is recommended in case of modified demand (e.g. due to Open matrix or Edit matrix data 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 less 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 routes compared to the result of a new assignment without this option, since in the Equilibrium assignment there are numerous possible routes which satisfy the Edwardian principle. If this option has not been selected, the assignment is calculated completely.
Multithreading	Number of zones to be balanced in parallel Enter the number of zones to be calculated simultaneously. The number is based on the number of real processor cores on your computer. This setting applies independently of the settings made under Edit > User preferences > Work environment (Specifying the number of processor cores to be used). Tip The maximum computation speed can be reached with 3 or 4 zones, even if your computer had more processor cores built in. With a greater number, conflicts might occur during the balancing step calculations, which would slow down the computation. Notes To reproduce the results, the same number of zones has to be set here. To minimize the deviation in the case of a different number of processor cores, enter a value less than 10-6 for Maximum gap. Based on system information, Visum identifies the number of physical processor cores and, if required, limits the maximum number of threads to the number of processor cores.
Optimization of the proportionality of route volumes along meshes	No optimization Path volumes are not harmonized Separate balancing for each transport system Path volumes are harmonized separately per transport system (Fundamentals: Proportionality in route distribution). Balancing over all transport systems Path volumes are harmonized jointly for all transport systems, if possible (Fundamentals: Proportionality in route distribution).

Equilibrium assignment LUCE: Convergence criteria tab

Element	Description
Use classical convergence criteria	If this option is selected, the classic 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.
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.
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. In addition, 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.

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