Create a Scenario - bellevuewa/BKRCast GitHub Wiki

The BKRCast model can be updated to reflect changes in existing conditions such as transportation infrastructure, land use, and household/person socioeconomics. The following list represents several example change scenarios:

Network Changes

Changes to the highway or transit network can be reflected in the BKRCast model by editing the networks in an Emme environment and then exporting the networks in a format used in the model system.

For example, the highway network could experience an increase or decrease in the number of roads. Additionally, the attributes of these roads could change, including the number of lanes, speed, and availability of HOV lanes. The transit network could also receive additional transit service or transit stops, in addition to route modifications, fare updates, and headway updates, among other changes. One or more of the following network-related files should be updated depending on the nature of network change:

Name Highway Transit Description
inputs/networks/[tod]_roadway.in x Roadway network file by time of day (tod): am, md, pm, ni
inputs/networks/[tod]_linkshape.in x Roadway network shape by time of day (tod): am, md, pm, ni
inputs/networks/[tod]_transit.in x Transit network file by time of day (tod): am, md, pm, ni
inputs/networks/[tod]_turns.in x Turns network file by time of day (tod): am, md, pm, ni
inputs/networks/vehicles.txt x List of transit vehicles and characteristics
inputs/networks/modes.txt x x List of modes and their characteristics
inputs/networks/sc_headways.csv x Transit headways by route and time period
inputs/networks/rdly/[tod]_rdly.txt x Road delays by time of day (tod): am, md, pm, ni
inputs/networks/fixes/[tod]_roadway.in x Roadway network changes for ferries by time of day (tod): am, md, pm, ni; these files provide additional network changes
inputs/accessibility/transit_stops_2014.csv x A list of transit stops with submode flags; the file is structured as: light_rail, commuter_rail, brt, ferry, bus, express, x_coord (feet), y_coord (feet)

The DaySim input file inputs/p_r_nodes.csv should be updated if network changes resulted in changes to park-and-ride locations. The details of the fields in the file are provided here

Employment Change

Some BKRCast model areas may experience growth/decline in employment due to increase/decrease in business establishments or other reasons. In addition, the distribution of employment types could change. The following DaySim input file should be updated to reflect these changes:

  • Primary parcel file (parcels_file_folder/parcels_urbansim.txt)

Make sure to check the taz_p field if PSRC provides the parcel file used for the update. This is because the file must first be converted to the BKRCast TAZ system if it is based on the SoundCast TAZ system. A utility script psrc2bkr_parcel.py can be used for this conversion.

Confirm that run_accessibility_calcs=True is in the input configuration file (input_configuration.py) after updating the primary parcel file and before starting a model run.

Population Change

Population in the BKRCast model region is likely to increase in the future. However, population in the model region may not increase in a geographically proportionate manner. A change in employment may also alter the existing geographic distribution of the population. The following two input files should be updated to accommodate a change in population in the model region:

  • Primary parcel file - parcels_file_folder/parcels_urbansim.txt
  • Synthetic population - inputs/hh_and_persons.h5

The synthetic population was generated by PSRC. For more details about the synthetic population process go here. Before starting a new model run, confirm that run_accessibility_calcs=True is in the input configuration file (input_configuration.py).

Update Model Coefficients

The BKRCast model system may need to be calibrated and validated with new datasets (when these become available) to further improve the representation of regional travel patterns. Calibration of the resident travel pattern will produce updated DaySim coefficient files. For more information about how to calibrate DaySim visit the Calibration & Validation page.The updated coefficients files should be replaced in the coefficients folder under the inputs directory.

Descriptions of the coefficient files are provided here.

Adding/Splitting a Zone

A future scenario may require modifying existing zones in the BKRCast model system. The modifications may include splitting an existing zone into multiple zones or merging several zones into one. These changes would result in new zone labels and zonal attributes for the affected zones. The affected zones should be updated or added to the model system, which requires updates to the following model inputs:

  • Primary parcel file (urbansim_parcels.txt). Update zone correspondence (taz_p) of the parcels residing in the affected zones. It is assumed that a zone is split along the parcel edges, which means that no parcel would correspond to more than one zone. Details of the parcel file are here.

  • Zone index file (TAZIndex.txt). Update zone IDs and corresponding fields in the zone index file. This file is an input to DaySim and indicates which zone numbers are valid. Details of the zone index file are here.

  • Synthetic population (hh_and_persons.h5). Update household zone (hhtaz) in HOUSEHOLD and usual work location (pwtaz) and usual school location (pstaz) in PERSON for the households and persons in the affected zones. The synthetic population file is an input to DaySim and provides population (households and persons) characteristics of the model region. Details of the synthetic population file are here.

  • Zone to district correspondence (TAZ_District_CrossWalk.csv). Update/add the zone IDs and corresponding districts in the correspondence file for the affected zones. This file is used in the popsampler process to identify zones corresponding to a district. Details of the zone index file are here.

  • Intrazonal files. The following intrazonal-related files should be updated to reflect the affected zones.

    • Origin terminal times (origin.tt). Update/add terminal times at the affected origin zones.
    • Destination terminal times (destination.tt). Update/add terminal times at the affected destination zones.
    • Zone area (taz_acres.in). Update/add zones and corresponding areas for the affected zones.

    Details of the intrazonal files are provided here.

  • Truck files. Several truck files should be updated to reflect the affected zones in the truck model.

    • Zone partitions (district19_ga.ens). Update/add zone partition for the affected zones.
    • Zonal data (tazdata.in). Update land-use variables (households by income, employment, group quarter population, college [full-time] enrollment) for the affected zones.
    • Household empoyment data (hhemp.in). Update/add household and employment data for the affected zones.
    • Truck shares (agshar.in, equipshar.in, minshar.in, prodshar.in, tcushar.in, whlshar.in). Update/add employment shares by industry type for the affected zones.
    • External trips (medium_trucks_ee.in, medium_trucks_ie.in, medium_trucks_ei.in, heavy_trucks_ee.in, heavy_trucks_ie.in, heavy_trucks_ei.in). Update/add internal-external trips by truck type (medium or heavy) for the affected zones, if applicable.

    Details of the truck files are provided here.

Split a Zone

The steps below describes necessary changes in land use, network, and other supporting input files for a zone split.

  1. Modify parcel/BKRCastTAZ columns in land use input file provided by community Development to reflect the latest change in zone split.

  2. In I:\Modeling and Analysis Group\07_ModelDevelopment&Upgrade\NextgenerationModel, copy BasicData to BasicData_for_zone_split_test.

  3. Revise all files inside this folder (AND subfolders) to reflect the latest changes made for the new zone split.

  4. In Z:\Modeling Group\BKRCast. Copy CommonData to CommonData_for_zone_split_test.

  5. Revise all files inside this folder to reflect the latest changes made for the new zone split.

  6. Copy Z:\Modeling Group\BKRCast\SoundCast\2050_Inputs\2050_SC_parcels_bkr.txt to "Z:\Modeling Group\BKRCast\CommonData_for_zone_split_test\2050_SC_parcels_bkr.txt". Revise this file to reflect the latest change in zone split.

  7. Run Convert_PSRC_TAZ_to_BKRCastTAZ_pop.py to regenerate 2014 and 2050 (or other horizon years that will be used for interpolation) synthetic population in BKRCast TAZ format.

  8. Run scripts to generate parcel files and synthetic population as regular steps.

  9. The following files need to be modified to reflect all changes due to a zone split.
    inputs\

    • TAZ_District_CrossWalk.csv
    • TAZ_TAD_County.csv
    • TAZIndex.txt
    • parking_gz.csv
      IntraZonals\
    • destination.in
    • origin.in
    • taz_acres.in
      Subarea_definition\
    • All applicable files

  10. Applicable files in Truck and supplemental models should also be revised to accommodate the latest changes in TAZ.