This section provides guidance on steps necessary to perform in order to reflect the changes in existing model conditions such as transportation infrastructure, land use, or household/person socio-economics. Following are a few such scenarios:
Employment Change
In future, some areas may see growth/decline in employment due to increase/decrease in business establishments or some other reasons. In addition, the distribution of different employment types could change over the years.
In order to reflect those changes in the model DaySim buffered parcel file needs to be updated - \Master\{SCENARIO_DIR}\ Input\DaySimInput\02_Parcel\ Jacksonville_parcel_decayandCirc.dat.
To update the file, two steps should be performed:
- If employment at a TAZ is same, including in different sectors, but distribution of employment in parcels within the TAZ have changed then either of the two should be undertaken:
- Edit the parcel file manually.
- Get new block level controls (with employment in 2-digit NAICS categories) and run the allocation tool (see section 5.1 |) to obtain an updated parcel file.
- If employment (or/and distribution of employment sectors) at a TAZ is different, the new TAZ file should be used to run the allocation tool (see section 5.1 |). The tool will produce an updated parcel file.
- The first step would create a new parcel file and an updated TAZ file, if necessary. The new parcel file should be provided as input to the buffering too (see section 5.1 | ) and generate a new buffered parcel file. This file should then be replaced in the DaySimInput folder.
Population Change
After a base year population has been synthesized, new synthetic populations may need to be generated based on the type scenario being run or the policy being tested. For example, a change in the network may not require the population to be synthesized again. On the other hand, if a land-use policy variable is being tested which would result in significantly different patterns in the population and employment levels in the TAZs than in the base case, a new synthetic population would be have to be generated. The same would be the case for a future year run when the population mix or distribution of specific population characteristics may deviate from those in the base synthetic population. Population is likely to increase in future, however, it may not increase proportionately geographically. A change in employment may also alter the existing geographic distribution of the population. To accommodate a change in population following three input files need to be updated:
- Buffered parcel file (\Master\{SCENARIO_DIR}\Input\DaySimInput\02_Parcel\ Jacksonville_parcel_decayandCirc.dat)
- Household file (\Master\{SCENARIO_DIR}\Input\DaySimInput\03_Household\_jax_hrec.dat)
- Person file (\Master\{SCENARIO_DIR}\Input\DaySimInput\04_Person\_jax_prec.dat)
To update the buffered parcel file, the similar steps as employment change accommodation needs to be performed. First, the parcel file (output of the allocation tool) is updated and then it is used in the buffering tool to generate a new buffered parcel file that goes into DaySim.
Synthetic population data (household and person files) would also need updates. As previously described, the synthetic population is generated using PopGen. The marginal control files for population synthesis need to be updated to reflect the new control totals. After that synthetic population needs to be generated using the new input files (Please refer to PopGen guide for synthesis instructions).