Select Query Analysis

The "Select Query Analysis" feature is an advanced tool for transportation network analysis. It enables users to define a set of links, zones, or nodes and generate an Origin-Destination (OD) table, as well as link volumes for the trips passing through the selected links, nodes, or zones. This functionality provides valuable insights into trip patterns and network performance, facilitating informed decision-making in transportation planning and management.

The following steps show the process of using this feature in TDM23:

1. Prepare:

To conduct the Select Query Analysis, the results from a complete model run are necessary. Please select the desired scenario and perform a full model run if it hasn't been done yet.

2.Generate Query File:

Generate an input query (.qry) file for the links, zones, or nodes to study. The analysis will be for either highway or transit.

  • Highway: Generate a highway link by using the Select Link/Zone Query Builder in TransCAD 9 ("Planning > Assignment Utilities > Select Link/Zone Query Builder"). Load the roadway network (LinkNodes.dbd), select your queries on the Links layer, and save your query as local .qry file.

    Detailed information on how to use the Select Link/Zone Query Builder can be found in TransCAD 9. Go to TransCAD Help under the Select Link/Zone Analysis thread.

  • Transit: Generate a transit link by using the Public Transport Select Link Query Builder in TransCAD 9 (“Public Transport > Assignment > Public Transport Select Link Query Builder”). Load the transit network (RoutesStops.rts), select your queries on the Routes layer, and save your query as local .qry file.

    Detailed information on how to use the Public Transport Select Link Query Builder can be found in TransCAD 9. Go to TransCAD Help under the Results of Public Transport Assignment thread.

3. Run:

Ensure you are in the desired scenario with results. Under the "CTPS_TDM23" menu, click "Select Query Analysis."

SQA menu

A dialog box will appear, displaying the selected scenario.

SQA dialog

Follow the steps below to configure and run your analysis:

  • Mode Selection: Choose between highway or transit modes.
  • Time Periods: Select the desired time periods for the analysis. Available options are AM, MD, PM, and NT. am (Morning Peak), md (Midday), pm (Afternoon Peak), and nt (Night).
  • Query File: Select the .qry file you wish to analyze. Click on the ellipsis ("...") to browse and select the file. The chosen file path will be shown on the left.
  • Results Directory: Specify the folder where the analysis results will be saved. Click on the ellipsis ("...") to choose the destination folder. The selected path will appear on the left.
  • Execute: Click on "Run" to start the analysis. Upon successful completion, a confirmation message will appear. If an error occurs, refer to the Troubleshooting section below.
Troubleshooting

  • Scenario Validation: Ensure that the scenario contains valid results before running the analysis.

  • Time Period Requirement: At least one time period must be selected. If none is selected, a prompt will display the message: "At least one time period should be selected."

  • Transit Route Availability: When running the analysis for specific transit routes, verify that the chosen routes are available during the chosen time periods to avoid errors such as empty matrix files.

4. Check Outputs:

There are two types of outputs generated by this feature:

  • Origin-Destination (OD) matrix file: This file indicates the number of trips originating from a row centroid ID and destined to a column centroid ID, passing through the specified set of links, zones, or nodes.

  • Unique flow fields in the assignment table: These fields represent the flow component on links passing through the specified set of links, zones, or nodes. In other words, it represents how trips that pass through the specified, select link are distributed across the network.