Select Query Analysis

The "Select Query Analysis" feature is a robust 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 open, displaying the selected scenario. Follow these steps to run the Select Query Analysis:

  • Specify whether the analysis is for highway or transit.
  • Enter the path for the “.qry” file.
  • Enter the path to the folder where the results will be saved.
  • Click "Run" to execute the analysis.

SQA dialog

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.