Running day type simulations using DTA mode

One of the functions of the TRE simulation tool is the ability to perform Dynamic Traffic Assignment (DTA). This process updates route choices at every iteration until a dynamic user equilibrium is reached over the network.

Limitations of DTA

On the one hand, the process is formally correct from the point of view of dynamic equilibrium. On the other hand, route choices are computed from scratch by TRE using the dynamic shortest path method. This often yields inconsistencies when comparing assigned flows with measured flows, as the resulting route choice could in principle differ from the one used in the methodology chosen for the correction of demand matrices (usually TFlowFuzzy with static assignment).

You need to evaluate whether these deviations are acceptable and correct (→ Evaluating day type simulations).

For each day type, TRE performs a daily simulation. The input of the daily simulation is given:

  • By the assignment graph (primary network only)
  • By OD matrices and by demand time series (from corrected OD matrices)

Each daily traffic assignment produces an estimation of traffic conditions for the entire network, simulated all over the day (for example, using a 15 minutes aggregation interval). Results of dynamic assignments are:

  • Link results (for example, every 15 minutes), which contain estimations of main traffic variables (flow, speed, density, queue, travel time)
  • Turn probabilities

TRE reads the input model either:

  • From Visum format (.net, .dem, and .xml files) in case of the TDE workflow
  • Directly form a temporary Optima database (PosgreSQL database format) in case of the TMB workflow

TRE needs to be configured to simulate each modeled day type for the duration of an entire day. For details on Short-Term Forecast configuration: → Traffic Real-time Equilibrium (TRE).

TRE writes the output of the simulation (for each day type) to an Optima database.

  1. Copy the template command line \TRE\config-templates\TRE offline.csv to the \TRE\ main folder and rename it to CommandLineTDE.csv.
  2. Open CommandLineTDE.csv with a text editor.

  3. Edit the following parameters. Insert each parameter value into the row below the parameter.

    • DS_MAIN: Input type (in this case Visum, coded as visum), followed by a colon, and then followed by the local path of the Visum model export files (without extension).

      Example: visum:c:\my_visum_model

    • DS_TPRB_OUT: Location where the turn probabilities produced as output of the simulation will be stored. In this case, the output type is Optima database (coded as postgresql), followed by a colon and then followed by the connection string to the temporary Optima database.

      Example : postgresql:Server=localhost;Port=5432;Uid=postgres;
      Pwd=postgres;Database=optima;CommandTimeout=3600      .

      Configure all parameters of the connection string properly.

    • DS_OPUT: Location where the simulation output will be stored. The output type is Optima database (coded as postgresql), followed by a colon, and then followed by the connection string to the temporary Optima database.

      Example: “postgresql:Server=localhost;Port=5432;Uid=postgres;
      Pwd=postgres;Database=optima;CommandTimeout=3600”      .

      Configure all parameters of the connection string properly.

    • DAYT: ID of the day type to simulate. You need to run a simulation for each day type, so you need to change this option before each TRE run.

      The simulation output for all day types will be saved together in the same Optima database. If a TRE simulation runs twice on the same day type, the results of the first simulation will be overwritten by the results of the second simulation.

  4. Save the file CommandLineTDE.csv.

  5. Double-click the file TRE.exe to execute Short-Term Forecast.

    The TRE window opens.

  6. Click the Execute button and wait until the end of the simulation.
  7. Check theTRE log file <name_of_the_model>_LogFile_TRE_offline.log in the Visum export files folder.
  8. Repeat steps 2 through 6 for each modeled day type by changing the parameter DAYT.
  1. Copy the template command line \TRE\config-templates\TRE offline.csv to the \TRE\ main folder and rename it to CommandLineTDE.csv.

  2. Open CommandLineTDE.csv with a text editor and edit the following parameters. (Insert the value of a parameter into the row below the parameter.)

    • DS_MAIN: Input type (in this case Optima database, coded as postgresql), followed by a colon and then followed by the connection string of the temporary Optima database.

      Example: “postgresql:Server=localhost;Port=5432;Uid=postgres;
      Pwd=postgres;Database=optima;CommandTimeout=3600      ”.

      Configure all parameters of the connection string properly.

    • DS_TPRB_OUT: Location where the turn probabilities produced as output of the simulation will be stored. In this case, it is sufficient to set the value to −1 to use the same value defined in the DS_MAIN parameter.

    • DS_OPUT: Location where the simulation output will be stored. In this case, it is sufficient to set the value to −1 to use the same value defined in the DS_MAIN parameter.

    • DAYT: ID of the day type to simulate. You need to run a simulation for each day type, so you need to change this option before each TRE run.

      The simulation output for all day types will be saved together in the same Optima database. If a TRE simulation runs twice on the same day type, the results of the first simulation will be overwritten by the results of the second simulation.

  3. Save the file CommandLineTDE.csv.

  4. Double-click the file TRE.exe to execute TRE.

    The TRE window opens.

  5. Click the Execute button and wait until the end of the simulation.
  6. Check the TRE log file <name_of_the_model>_LogFile_TRE_offline.log in the Visum export files folder.
  7. Repeat steps 2 through 6 for each modeled day type by changing the parameter DAYT.