Cover Image

Not for Sale



View/Hide Left Panel
Click for next page ( 194


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 193
182 I N N O VAT I O N S I N T R AV E L D E M A N D M O D E L I N G , V O L U M E 2 dom number series to determine which possibility is cho- Linux 32-bit OS sen for that record. Networking Specifications The new model is implemented with three global feed- 5 port 10/100/1000 Gigabit network switch back loops for consistency between highway travel times CAT6 Ethernet cable that are both used as inputs to, and as forecast outputs of, the model. The workers are directly networked and are isolated The main model application package is Cube, with from the general MORPC network to make them less TP+ being used for network management, assignment, susceptible to viruses. The workers are not running anti- external, and commercial vehicle models and other pro- virus software every time a file is accessed, unlike the rest cessing. The core tour-based choice models described of the MORPC network; it was found that running anti- above are written in Java with access to the TP+ skims. virus software imposed a 15% penalty on the run time. The custom programs are designed to take advantage of In December 2005, a fourth worker was added to the the numerous opportunities for parallel processing in the cluster. This first system is running 32-bit OSs and Java. model chain, multi-threading of tasks, and to readily The second system was purchased by the Central accommodate the addition of computers in the distribu- Ohio Transit Authority (COTA) in support of its North tive processing framework to optimize processing. Corridor Transit Project DEIS. This cluster consists of After the networks and initial skims are generated in one server and four workers all running 64-bit Windows TP+ and all input files are created for a particular sce- and Java. The specifications for this cluster are below. nario, the custom Java programs are executed to imple- ment the tour-based microsimulation models. A Server pre-assignment processor step aggregates the microsimu- Dual 64-bit AMD Opteron 2.2 GHz 1MB L2 lation results and integrates the commercial and external Cache Processors models to produce standard TP+ trip tables for four time 4 GB PC3200 ECC Registered DDR Memory periods. After the final trip tables are generated, vehicles 4 - 73GB SCSI U320 10K RPM RAID-5 Array are assigned with a multi-class (SOV, HOV, medium Dual Gigabit network interface cards truck, and heavy truck) equilibrium assignment utilizing Windows 2003 Server 64-bit OS 21 volume delay functions by facility and area type for Worker (4) each of four time periods (a.m., midday, p.m., and night). Dual 64-bit AMD Opteron 2.2 GHz 1MB L2 Transit assignments are also performed in TP+ for the Cache Processors a.m. and midday time periods, with standard reports 4 GB PC3200 ECC Registered DDR Memory generated to support analysis and evaluation of the alter- 160 GB SATA NCQ HDD natives tested (Anderson et al. 2003). Dual Gigabit network interface card Windows XP Professional 64-bit OS HARDWARE CONFIGURATIONS MODEL RUNNING TIMES There are three operational systems that can run the MORPC travel forecasting model. The two systems that Table 1 shows the running times of the MORPC Travel are currently installed at MORPC are the topic of this Forecasting Model for 2000 and 2030 on the various paper. The initial system was built in December 2004 computer systems. MORPC 3 is the MORPC system with one server computer and three worker computers. with three Linux workers running 32-bit OSs, MORPC The specifications for the computers are below. 4 is the MORPC system with four Linux Workers run- ning 32-bit OSs, and COTA is the COTA system with Server four Windows XP Workers running 64-bit OSs. The Dual 64-bit Xeon 3.6 GHz 1MB L2 800MHz 2000 model has 1.5 million synthetic people making 2 FSB Processors million tours; 2030 has 2 million synthetic people mak- 4 GB PC3200 ECC Registered DDR Memory ing 3 million tours. All runs include only two transit 4 - 36GB SCSI 15K U320 RAID-5 Array modes (local and express bus). The core model running Dual Gigabit network interface cards time does not include the time to generate the four-period Windows 2000 Server Operating System (OS) highway networks, two-period transit networks includ- Worker (34) ing support links, or the time to generate the initial travel Dual Xeon 3.06 GHz 512KB L2 533MHz FSB skims, which is similar to the time to generate the travel 2 GB PC2100 ECC Registered DDR Memory skims during the model run. Overall, the time for these 120 GB IDE HDD excluded tasks is about 2 h of running time on a 32-bit Gigabit network interface card Windows computer.