Master Transportation Plan Medium-Term Modeling Analysis
3.2.4 Calibration Process and Results The counts at specific locations identified for the medium-term analysis (i.e. 51 key locations mentioned in the previous section) were used as calibration targets for the Origin-Destination Matrix Estimation (ODME). The ODME procedure adjusted trip matrices to improve assignment accuracy at these locations. This process was implemented separately for each time period and for the four classes: DA, SR, MT and HT. TransCAD’s multimodal assignment ODME with the gradient method was applied for this analysis. Since the procedure requires a single value of time (VOT) per class, weighted average VOTs were derived from the original 12 vehicle classes (see Table 4).
Table 4: Adjusted VOT to four classes Vehicle Class VOT AM
VOT PM
VOT OP
1.18 0.83
0.58 0.36
0.40 0.26
Drive-alone (DA) Shared ride (SR)
Medium truck (MT) Heavy truck (HT)
1.5 1.5
1 1
1 1
The ODME-adjusted matrix was then reassigned, and discrepancies at certain locations were further addressed using Select Link Analysis (SLA) and manual network adjustments were necessary. This iterative calibration process ensured that the final assigned volumes matched observed counts to a reasonable degree and that modeled flows represented realistic travel patterns in the CoFW study area. The results after calibration are shown in Figure 10 to Figure 16. These results show that a much closer fit was achieved through the calibration process, focusing on reducing the percent error and results at key locations.
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