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

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Suggested Citation:"T57054 txt_183.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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Times for the individual model components are shown for Iteration 1. At the end of Iterations 1 and 2, the a.m. and midday highway trips are assigned and the congested networks are then skimmed for feedback to the next iteration. Afternoon and night skims are the transposed a.m. and midday skims. At the end of the third iteration, all highway and transit trips are assigned to the appropriate network. As seen from Table 1, 2030 takes longer to run than 2000 due to the additional population and tours. The addition of the fourth worker on the MORPC system improves the running time on the DTM and Stops mod- els. The COTA system shows the most significant improvement in running times due to 64-bit computing and runs substantially faster than the 32-bit MORPC system. Therefore, any future installations of the MORPC model system would almost certainly involve 64-bit computing. All run times are based on Cube Version 3.2. All TP+ programs are run on the server in sequential order. It has been found that Windows will only allocate a maximum of 50% of its CPU power to any one application. There- fore, if the TP+ scripts were run in parallel, a significant time savings could result. Future upgrades include installing Cube on the systems of the COTA workers and sending TP+ scripts to run in parallel. This is not possible on the MORPC system as the workers are running Linux. MORPC MODELING STAFF MORPC employs three staff members who use the travel forecasting model directly. Responsibilities are broken down roughly as follows: • Senior Engineer: This person manages the model development and is familiar with the theory behind the model. This person runs the model for projects when needed and would proffer new features to be added to the model. This job includes model validation and cali- bration and script writing in support thereof. • Associate Engineers (2): These people run the model for project- level analysis and air quality confor- mity. They maintain and upgrade the highway and tran- sit networks. In addition to the staff above, MORPC employs five staff members who maintain and forecast the socio- conomic variables and two others who use the model results. 183HARDWARE REQUIREMENTS AND RUNNING TIME TABLE 1 2000 and 2030 Running Times of the MORPC Travel Models (Hour:Min) 2000 2030 MORP C 3 MORPC 4 COTA MORPC 3 MORPC 4 COTA Households Population Tours 610,774 1,435,389 2,074,618 610,774 1,435,389 2,073,659 610,774 1,435,389 2,075,797 872,919 1,956,660 2,997,507 872,919 1,956,660 2,997,214 872,919 1,956,660 2,996,117 Core model total (3 iterations) Iteration 1 Iteration 2 Iteration 3 Iter 1 - Population synthesis Iter 1 - Sending files to workers Iter 1 - Auto ownership Iter 1 - Mandatory tour generation Iter 1 - Mandatory DTM Iter 1 - Joint tour generation Iter 1 - Joint tour DTM Iter 1 - Individual tour generation Iter 1 – Individual tour DTM Iter 1 - At-work subtour DTM Iter 1 - Mandatory stops model Iter 1 - Joint stops model Iter 1 - Individual stops model Iter 1 - At-work stops model Iter 1 - Writing files and trip tables Iter 1 - External model + Iter 1 - Commercial vehicles + Iter 1 - IE trips + Iter 1 - Highway assignment - 2 period + Iter 1 - Highway and transit network skimming + Iter 3 - Highway assignment - 4 period + Iter 3 - Transit assignment - 2 period + 35:43 11:27 11:26 12:49 0:02 0:20 0:01 0:53 4:01 0:12 0:08 0:05 0:54 0:08 0:49 0:07 0:54 0:06 0:13 0:00 0:02 0:00 1:08 1:17 2:14 0:16 31:20 10:08 9:55 11:16 0:02 0:20 0:01 0:53 3:14 0:12 0:06 0:05 0:41 0:07 0:38 0:06 0:43 0:05 0:13 0:00 0:02 0:00 1:14 1:17 2:18 0:16 20:55 6:51 6:28 7:36 0:01 0:12 0:00 0:39 1:59 0:08 0:04 0:05 0:23 0:06 0:21 0:04 0:24 0:04 0:10 0:00 0:01 0:00 1:07 0:53 1:51 0:10 48:35 16:18 14:59 17:17 0:02 0:19 0:02 1:15 6:07 0:14 0:08 0:07 1:15 0:12 1:14 0:08 1:11 0:09 0:35 0:01 0:02 0:00 2:03 1:04 3:11 0:12 41:23 13:28 12:48 15:06 0:02 0:20 0:02 1:15 4:48 0:14 0:07 0:07 0:56 0:10 0:59 0:07 0:54 0:08 0:34 0:01 0:02 0:00 1:31 1:03 3:07 0:12 26:43 8:30 8:06 10:06 0:01 0:14 0:01 0:39 2:50 0:08 0:05 0:05 0:30 0:07 0:32 0:05 0:31 0:05 0:26 0:01 0:01 0:00 1:16 0:44 2:19 0:07

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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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