13.3.2 Data Requirements Determination

It is of key importance that sufficient data be collected to calibrate and validate a microsimulation model. Loop counts, video counts, probe-based data, travel time runs, intersection TMCs, and in-person observations are typically performed when field data is collected for microsimulation models. However, with the FHWA 2019 Guidelines, the following data collection sources are recommended to be able to perform cluster analysis and determine travel conditions:
  • Demand;
    • Permanent count locations from STARS II within and/or adjacent to the project.
    • Lonestar has data available for urban/metro Districts.
    • OD data from Big Data sources or OD trip tables from TDMs to determine travel patterns.
  • Weather;
    • The National Weather Service (NWS) or similar sources for data on precipitation, wind speed, snow, visibility, etc.
  • Incident;
    • Local area traffic management centers.
    • TxDOT’s CRIS data to identify crashes that occurred on the facility by time of day.
  • Transit;
    • Local transit authority for data related to ridership, routes, transit stops, etc. within the study area.
  • Freight;
    • Classification counts or permanent counters
    • TxDOT’s Statewide Planning Map
  • Bottleneck Throughput; and
    • Stationary bottleneck location data within the study area.
    • Bottleneck throughput data via traffic counts upstream and downstream of the bottleneck (within 0.5 miles of the bottleneck and upstream of any major interchanges or intersections.)
  • Travel Time
    • Big data sources such as INRIX or others can be used.
FHWA recommends collecting a year’s worth of data to perform cluster analysis. Collect at least 100 days of traffic data from permanent counters on STARS II website, Traffic Management Centers, Travel Times from INRIX or other Big Data sources. For projects that require FHWA review or approval, coordinate with FHWA regarding an acceptable data collection methodology if FHWA’s data collection recommendations cannot be met.