Travel Modelling Group
MEMORANDUM
Date:2012-05-28
Number:2012-10
To:TMG Technical Advisory Committee
From:Michael Hain
Subject:Data for auto assignment parameter calibration
Several types of data were prepared for calibrating auto assignment parameters. They include travel times on 400 series highways and some arterial roads, travel times for OD pairs and screenline counts at municipal boundaries or other important points. Each of these sets of data consists of three files: an EMME batch file, a correspondence file and a truth file.
The EMME batch file is used to establish extra attribute codes in EMME to identify the links which have truth values associated with them. Extra attributes must be created in EMME to hold these codes. In the case of link travel times, the extra attribute names are @ttlfg and @ttflg as defined in modellerTool_TravelTimes.py. OD pairs with travel times are hard coded in the same tool. For screenline data, the names of the extra attributes are @slc and @aslc as defined in modellerTool_ScreenlineCounts.py. Whether modellerTool_RoadAssign.py outputs travel times and screenlines are independently controlled by call parameters, however, XTMF can only consider one of them at a time.
The correspondence file establishes the link between the code from EMME and the identifier in the truth file. In the cases of travel times and screenline counts, the two files typically use the same identifiers (unlike the transit line boardings). The file is in .csv format with the first column listing the truth value’s identifier and the second column the EMME identifier.
The truth file lists values that are used as targets for the calibration process. The file is in .csv format. The first column is the value taken as a target and the second column is the identifier. In the case of the transit line truth file, the third column is the mode of the transit line.
Some of the available triplets of EMME batch file, correspondence file and truth file are listed in Table 1. The data used to produce these files are described in more detail in TMG memos 2012-12 and 2012-13.
Table 1: File combinations for auto assignment parameter calibration
EMME batch file / Correspondence file / Truth file2006_SLC_aSLC.in (@aslc) / MajorScreenlineCorrespondences.csv / MajorScreenlineCountTruth.csv
2006_SLC_aSLC.in (@slc) / StationCorrespondences.csv / StationCouthTruth.csv
2006_ttflg.in (@ttflg) / CodeToCode.csv / CodeTravelTimeTruth.csv
2006_ttflg.in (@ttlfg) / LinkToLink.csv / LinkTravelTimeTruth.csv
(hard coded OD travel time flags) / ODToOD.csv / ODTravelTimeTruth.csv
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