Embedded Files
Input files specifying land use are located in the Inputs\SEData folder. See the Land Use Inputs page for a list of files and associated data dictionaries.
Also included on this page is a discussion on updating the special generator, truck and external inputs. These files are located in the Inputs\SpecGenTrk folder. File descriptions and data dictionaries are available here.
Land Use - Population
Land Use - Population
The scenario population and households are maintained in two separate datasets: the synthetic population and the MAZ data file. The MAZ data file contains the total population and households from the synthetic population and must be updated when a new synthetic population is generated.
Changes to the model population should also maintain a general consistency with the employment and enrollment. For example, a reduction in the number of workers in the region, say under an aging-demographic scenario, should also have a reduced employment input.
Note that group-quarters (e.g. university dorms) are represented as single person households and these households
To produce a new synthetic data set, household and person control totals must be defined at the TAZ and MAZ level. Consistency across segments must be maintained. See the following section for instructions on use of the consistency checker available through the SERPM catalog to confirm segments are correct and to develop a new input set of control files.
Consistency Check Utility for Synthetic Population Inputs
Consistency Check Utility for Synthetic Population Inputs
For convenience, a consistency check utility is provided as part of the SERPM 8 catalog. The utility evaluates the following checks for consistency within and between the control total files:
TAZ Checksums
TAZ Checksums
- Child Segment
- GQ Segment
- Income Segment
- Person Age
- Size Segment
- Unit Segment
- Worker Segment
TAZ Household to Person Consistency
TAZ Household to Person Consistency
- HH Children with no Child persons
- HH Size != Total Persons (Size 4P==0)
- HH Size > Total Persons (Size 4P>0)
- HH Workers > Total Persons
- No HH with Children with Child persons
MAZ to TAZ Consistency
MAZ to TAZ Consistency
- No MAZ GQ with TAZ GQs - Multiple MAZs in TAZ
- No MAZ Housing with TAZ Households - Multiple MAZs in TAZ
- No MAZ GQ with TAZ GQs - Single MAZ in TAZ
- No MAZ Housing with TAZ Households - Single MAZ in TAZ
- MAZ GQ < TAZ GQ
- MAZ Housing < TAZ Households
To launch the utility
To launch the utility
Open the Utilities -> PopSyn Checker application group and double click the Pilot program labeled Run PopSyn Consistency Checks
The utility prompts for the location of:
- TAZ control file
- MAZ control file
An excel report titled PopSyn_Summary.xlsx is written to the folder containing the TAZ control file. This report contains tabs summarizing the number of zones, if any, with check issues, and lists the offending zones by county on separate tabs.
Utility to generate Synthetic Population Inputs
Utility to generate Synthetic Population Inputs
The PopSyn input generator is included as part of the catalog and is used to produce a new set of TAZ level control totals with consistent segments based on a seed set of distributions. The generator takes as input:
1. A reference set of PopSyn inputs, which will be used to determine the household size and segment distributions;
2. New population targets at the TAZ level; and
3. A set of PopSyn inputs to update. The records with a new population target will be replaced all other records will be carried through.
The generator first develops the distribution table, then derives a new households target and distributes the persons and households across the required segments. The distribution table is recorded for QA/QC purposes.
The overall process is shown in the following figure.
Building the distribution table
Building the distribution table
The distribution table is built from the identified seed set of PopSyn inputs. In order to build the distributions based on a significant baseline, a set of thresholds are implemented that ensure a minimum population, group-quarters household, and a reasonable average persons per 4+ household is effected. The default thresholds are:
- Minimum population of 200 persons
- Minimum Group Quarters of 100 units
- Maximum average 4+ household size of 7.5
If these thresholds are not met, the distribution is built at a higher level of spatial granularity: from TAZ to TAD to Super District.
The distribution shares and aggregate level are recorded as report files: TAZ_SEED_FILENAME_distributions.csv, MAZ_SEED_FILENAME_distributions.csv
Preparing new population targets
Preparing new population targets
The population target file is a csv file that must contain the following input columns:
- TAZ_REG: regional TAZ number
- TOTAL_PERSONS: new number of person for this TAZ
- TOTAL_GQ: new number of Group Quarters for this TAZ
Note that if the persons or group quarters is unchanged, the existing value should be set.
Also note that the population targets file need only contain the zones which have an updated population and/or group quarters.
To launch the utility
To launch the utility
Open the Utilities -> PopSyn Utilities application group and double click the Pilot program labeled Run PopSyn Input Generator
- Select a populated scenario
- Double click the PILOT program PopSyn Input Generator
- Follow the prompts to identify the input files for:
- Population target file
- Seed PopSyn Input files (TAZ and MAZ)
- PopSyn Input Files to update (TAZ and MAZ)
The updated files will be written to the Inputs\SEData\popsyn_inputs folder with the suffix _updated
Verifying correct operations
Verifying correct operations
The following output files can be checked to verify the correct operation of the PopSyn Input Generator. All of these files are written to the Inputs\SEData\ popsyn_inputs folder.
- Distribution files (files with shares and spatial granularity): TAZ_SEED_FILENAME_distributions.csv, MAZ_SEED_FILENAME_distributions.csv
- Difference files reporting change by TAZ and MAZ: TAZ_SEED_FILENAME_diffs.csv, MAZ_SEED_FILENAME_diffs.csv
Land Use - Employment and Enrollment
Land Use - Employment and Enrollment
Employment is recorded in the MAZ data file by category and as a total, with the exception of airport employment beyond TSA checkpoints. Airport employment beyond TSA checkpoints should be recorded as emp_trans and excluded from the total employment. Otherwise, SERPM 8 will overestimate the trips to the airports
Checking land use inputs
Checking land use inputs
The SEDataSummary*.xlsx report in the scenario _reports folder summarizes the synthetic population and MAZ data file inputs by super district, county, and for the entire region. This summary should be compared against the intended inputs to ensure correct operation.
Special generators, externals, and trucks
Special generators, externals, and trucks
The most common case of needing to update the special generator and external inputs is for an intermediate forecast years (e.g. 2030). Note that the internal truck trips are generated from the regional employment and do not need to be modified to represent an intermediate or extended forecast year.
- Each external station has a control total by external to external and external to internal trips. Changes to any type of external trip must maintain the overall control total
- Airport enplanements are based on FAA forecasts and should be updated for any intermediate year forecasts
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