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Innovations in Travel Demand Modeling, Volume 2: Papers (2008)

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Suggested Citation:"T57054 txt_146.pdf." National Academies of Sciences, Engineering, and Medicine. 2008. Innovations in Travel Demand Modeling, Volume 2: Papers. Washington, DC: The National Academies Press. doi: 10.17226/13678.
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cating a stronger negative effect on travel decisions for WH trips during the congested periods. • Shift variables—Two kinds of shift variables are computed, namely, shift early (SE) and shift later (SL), which measure the difference between the time period indicator (on a scale from 1 through 24 with 0.5 incre- ments) and the midpoint of the first three time periods (a.m., midday, and p.m. peak periods). SE is used when the time period indicator is less than the midpoint whereas SL is used when it is greater. The square of these variables is also used in the models to see the impact of very short and very long delays on temporal choice behavior. During model estimation, these shift variables are multiplied by the delay variable as well as other vari- ables to see the combined effect on time-of-day choice. The coefficients for the delay variables multiplied by SE and SL are significant and positive, while these are nega- tive when multiplied by the square of SE and SL. This indicates that travelers are more likely to switch their time choice when undertaking trips that may gen erate either very short or very long delays. The model statistics demonstrate that the rho-squared with respect to 0 is reasonable (0.191 for WH and 0.188 for HW), but the rho-squared with respect to the con- stants (0.003 for WH and 0.014 HW) shows that the con- stants account for nearly all the variation in time-of-day choices. While it may be desirable for the variables in the models to account for more of the time-of-day choices, the primary objective of the model is to provide sensitivity to trip characteristics, which is achieved by these models. Additional steps are carried out for the time-of-day models: • The models were estimated using the full set of variables listed above, with additional testing for the best specification of the shift variables. The estimation results by trip pur pose are shown in Tables 2, 3, and 4. 146 INNOVATIONS IN TRAVEL DEMAND MODELING, VOLUME 2 TABLE 2 Home-Based Work Time-of-Day Choice Model Home to Work Work to Home Observations 6,931 6,076 Final log L –19,500.8 –17,032.7 Rho-sq. (0) 0.188 0.191 Rho-sq. (constant) 0.014 0.003 Alternatives Variable Definition Coefficient t–Stat Coefficient t–Stat AM1–AM10 AM Delay max(0, AM GC – NI GC) –0.06172 –4.7 –0.4277 –3.2 MD1–MD10 MD Delay max(0, MD GC – NI GC) –0.2834 –6.0 –0.3935 –9.9 PM1–PM10 PM Delay max(0, PM GC – NI GC) –0.1747 –4.2 –0.100 constant EV EV Delay max(0, EV GC – NI GC) –0.1714 –5.7 AM1–AM5 AM Shift Early AM Delay x (7.5–t) 0.1121 7.7 AM1–AM5 AM Shift Early2 AM Delay x (7.5–t)2 –0.01914 –3.4 AM6–AM10 AM Shift Later AM Delay x (t–7.5) 0.01842 2.3 AM6–AM10 AM Shift Later2 AM Delay x (t–7.5)2 MD1–MD5 MD Shift Early MD Delay x (12.5–t) 0.1063 4.4 MD1–MD5 MD Shift Later MD Delay x (t–12.5) 0.09548 2.8 0.1144 4.6 PM1–PM5 PM Shift Early PM Delay x (17.0–t) 0.0766 2.8 0.09523 7.0 PM1–PM5 PM Shift Early2 PM Delay x (17.0–t)2 0 –0.03593 –4.8 PM6–PM10 PM Shift Later PM Delay x (t–17.0) 0.05933 1.8 0.1056 9.4 PM6–PM10 PM Shift Later2 PM Delay x (t–17.0)2 0 –0.03027 –6.0 AM1–AM10 AM HH size min(HH size,4) –0.3419 –7.6 AM1–AM10 AM Low Income HH income <$45K –0.5176 –5.9 AM1–AM10 AM High Income HH income >$75K 0.515 4.3 AM1–AM10 AM Crossing dummy(Bridge_N > 0) 0.3545 2.3 MD1–MD10 MD HH size min(HH size,4) –0.3427 –6.6 MD1–MD10 MD High Income HH income>$75K 0.461 3.4 0.6694 3.7 MD1–MD10 MD Shared ride dummy(car occ.>1) 0.479 3.8 –0.5917 –3.5 MD1–MD10 MD Crossing dummy(Bridge_N > 0) 0.618 2.6 PM1–PM10 PM HH size min(HH size,4) –0.05966 –2.1 PM1–PM10 PM High Income HH income >$75K 0.9454 5.6 PM1–PM10 PM Shared ride dummy(car occ.>1) 0.6686 4.2 –0.5694 –4.6 PM1–PM10 PM Crossing dummy(Bridge_N > 0) 0.6383 3.7 EV EV High Income HH income >$75K 0.5285 2.7 AM1–AM5 AM HS Shift Early AM HH Size x (7.5–t) 0.0722 4.0 AM1–AM5 AM HI Shift Early AM Low Inc x (7.5–t) 0.1194 2.3 AM1–AM5 AM HI Shift Early AM High Inc x (7.5–t) –0.1216 –2.8 AM1–AM5 AM BR Shift Early AM Crossing x (7.5–t) –0.4295 –5.8 AM6–AM10 AM LI Shift Late AM Low Inc x (t–7.5) 0.2483 3.8 PM1–PM5 PM HI Shift Early PM High Inc x (17.0–t) –0.2217 –4.1

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TRB Conference Proceedings 42, Innovations in Travel Demand Modeling, Volume 2: Papers includes the papers that were presented at a May 21-23, 2006, conference that examined advances in travel demand modeling, explored the opportunities and the challenges associated with the implementation of advanced travel models, and reviewed the skills and training necessary to apply new modeling techniques. TRB Conference Proceedings 42, Innovations in Travel Demand Modeling, Volume 1: Session Summaries is available online.

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