The accessibility calculator computes for each LUZ pair the logsum-based accessibilities for 2 time-of-day periods (off-peak, peak), 4 income categories (low, medium, high, very high), and 3 auto sufficiency categories (zero autos, number of autos greater than number of workers, number of autos less than or equal to number of workers). Thus, a total of 24 origin-based accessibilities are produced for each LUZ.

Section 11.1 Running the Calculator

The accessibility calculator is included in the ARC CT-RAMP Java archive file, arc.jar. It is currently set up to run on a single machine using 8 threads but can be configured to utilize additional computational resources through the “accessibility.properties” file under the project directory.

To run the calculator:

  1. Set Project.Directory in “accessibility.properties” to the current project directory.
  2. Run the batch file “Config/RunAccessibility.bat” under DOS command.

Section 11.2 Required Files

Table 11-1 lists the files required to run the accessibility calculator. All the input .csv and .xls files are specified through accessibility.properties.

Table 11-1 Files Needed to Run the Accessibility Calculator

File Name and Path (in relation to project directory Description
accessibilities.properties File containing property settings for the accessibility calculator
accessibility.csv TAZ-level accessibilities computed by main model script
zoneData.csv TAZ-level zonal data produced by main model script
ctrampModels/geographicCwalk.csv TAZ to LUZ lookup table
ctrampModels/accessibility_utility_constants.xls Constants to be added to the utility calculation for different auto sufficiency levels, modes, and purposes
ctrampModels/accessibility_utility.xls Mode choice utility equations for calculating logsums
ctrampModels/mandatory_accessibility_alts.csv Accessibilities defined for mandatory purpose
ctrampModels/nonMandatory_accessibility_alts.csv Accessibilities defined for non-mandatory purpose
Skims for AM, PM and MD periods Skims computed by main model script

Section 11.3 Output Files

The calculator produces 24 output files, one for each combination of time-of-day periods, income category, and auto sufficiency category. Table 11-2 lists the names of the accessibility 24 files and Table 11-3 describes the fields in each of these files. The calculator also produces a column-wise merge of all 24 accessibilities in “all_accessibilities.csv”. All output files are written to the “accessibility” sub-directory under the project folder.

Table 11-2 Accessibility Files Produced by the Accessibility Calculator

Time Period Output Files
Off-peak Period Op_lowInc_0_autos
Op_medInc_0_autos
Op_highInc_0_autos
Op_veryHighInc_0_autos
Op_lowInc_autos_lt_workers
Op_medInc_autos_lt_workers
Op_highInc_autos_lt_workers
Op_veryHighInc_autos_lt_workers
Op_lowInc_autos_ge_workers
Op_medInc_autos_ge_workers
Op_highInc_autos_ge_workers
Op_veryHighInc_autos_ge_workers
Peak Period Pk_lowInc_0_autos
Pk_medInc_0_autos
Pk_highInc_0_autos
Pk_veryHighInc_0_autos
Pk_lowInc_autos_lt_workers
Pk_medInc_autos_lt_workers
Pk_highInc_autos_lt_workers
Pk_veryHighInc_autos_lt_workers
Pk_lowInc_autos_ge_workers
Pk_medInc_autos_ge_workers
Pk_highInc_autos_ge_workers
Pk_veryHighInc_autos_ge_workers

Table 11-3 Content of Accessibility Files

Field Description
origLUZ Origin LUZ
destLUZ Destination LUZ
accessibility Accessibility between origLUZ and destLUZ
zone_pairs Number of TAZ pairs nested within the LUZ pair




Atlanta Regional Commission, 2019