Activity-Based Travel Demand Models: A Primer (2014) / Chapter Skim
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Pages 143-156
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From page 143... ...
141 The purpose of this chapter is to identify implementation issues that agencies face as they consider adopting new advanced integrated model tools and approaches. These issues have been grouped into fi ve categories that describe institutional issues, cost and schedule concerns, data requirements, software issues, and application challenges.
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From page 144... ...
142 Part 2: ISSUES IN ADOPTING INTEGRATED DYNAMIC MODELS SYSTEMS ing is more likely to arise from seeing examples from other regions or from hands-on experience working with integrated models. Thus, there is a conundrum that agencies are less likely to develop and apply advanced integrated models until there are more examples of agencies developing and applying such models.
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143 Chapter 6: IMPLEMENTATION ISSUES The overall pool of individuals with relevant experience in developing and applying either activity-based models or dynamic network models is relatively small, and the set of individuals with experience in both domains is even more limited. Agencies that are able to identify and hire staff with the appropriate understanding and skills may still face challenges in ensuring that these staff can be devoted to advanced integrated model development and application and not redirected to fulfill other agency responsibilities.
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144 Part 2: ISSUES IN ADOPTING INTEGRATED DYNAMIC MODELS SYSTEMS Potential Next Steps • Involve agency staff in all aspects of model development, enhancement, and application. • Include participation of multiple agencies from different regions in parallel integrated model implementation efforts.
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145 Chapter 6: IMPLEMENTATION ISSUES network modeling software has also significantly improved in recent years, with a number of software options providing improved run times, robust user interfaces, and tools to facilitate data development. But despite these software cost reductions and performance improvements, overall development costs for dynamic advanced integrated models are still higher than those for static model systems (AECOM 2010)
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146 Part 2: ISSUES IN ADOPTING INTEGRATED DYNAMIC MODELS SYSTEMS • Continue research into model transferability. • Include software development training.
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147 Chapter 6: IMPLEMENTATION ISSUES bilities and handle ever larger networks. In addition to the schedules required to implement the activity-based and dynamic network components, time is also required to design, implement, and evaluate methods for integrating these components.
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148 Part 2: ISSUES IN ADOPTING INTEGRATED DYNAMIC MODELS SYSTEMS Agencies like SANDAG and CMAP have recently initiated the development of integrated dynamic model systems as long-term strategic investments, similar to traditional trip-based model systems. These efforts, as well as the case examples of MAG's Phoenix Inner Loop Travel Model and SFCTA's DTA Anyway projects, point to shifts in how future model development efforts will be conceived and funded.
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149 Chapter 6: IMPLEMENTATION ISSUES significant time may be spent cleaning existing data or rectifying multiple inconsistent data sources (Resource Systems Group et al.
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150 Part 2: ISSUES IN ADOPTING INTEGRATED DYNAMIC MODELS SYSTEMS particular subarea or corridor. Such development limits the ability of agencies to revise and expand these network inputs as new information becomes available and analysis requirements are expanded.
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151 Chapter 6: IMPLEMENTATION ISSUES A very limited number of network simulation packages offer the ability to model transit pathbuilding and assignment. A key design consideration in developing an integrated dynamic model system is how the primary components will interact and exchange information.
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152 Part 2: ISSUES IN ADOPTING INTEGRATED DYNAMIC MODELS SYSTEMS modeling approach is used. The amount of spatial, temporal, and typological detail also influences model system run times, with increasing levels of detail resulting in longer run times.
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153 Chapter 6: IMPLEMENTATION ISSUES and subregional policy and investment alternatives. Both model systems implemented as part of the SHRP 2 C10 projects were used to evaluate a set of alternative scenarios, but significant research and investigation remains to be done.
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From page 156... ...
154 Part 2: ISSUES IN ADOPTING INTEGRATED DYNAMIC MODELS SYSTEMS • They are stochastic simulations. • They often take a long time to run.
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