The National Academies Press

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From page 38... ... 38 This chapter presents critical considerations related to accounting for CAVs in trip-based models. Along with the subsequent chapters on disaggregate/dynamic models and strategic models, Chapter 6 provides the context for the modeling adaptations and then an approach for implementing them. Read the entire page →
From page 39... ... Adapting Trip-Based Models to Address CAVs 39 such as trip rates and lengths, per person, needs to be done in the context of reasonableness as compared with historical trends. While trip rates and lengths may vary because of an urban area's characteristics and size, as a whole, trip making and the time spent in mobility activities is relatively stable. Read the entire page →
From page 40... ... 40 Updating Regional Transportation Planning and Modeling Tools to Address Impacts of Connected and Automated Vehicles Travel Statistic 1969 1977 1983 1990 1995 2001 2009 95% CI Per person Daily person trips 2.02 2.92 2.89 3.76 4.3 3.74 3.79 0.03 Daily PMT 19.51 25.95 25.05 34.91 38.67 36.89 36.13 1.35 Per driver Daily vehicle trips 2.32 2.34 2.36 3.26 3.57 3.35 3.02 0.03 Daily VMT 20.64 19.49 18.68 28.49 32.14 32.73 28.97 0.71 Per household Daily person trips 6.36 7.69 7.2 8.94 10.49 9.66 9.5 0.09 Daily PMT 61.55 68.27 62.47 83.06 94.41 95.24 90.42 3.38 Daily vehicle trips 3.83 3.95 4.07 5.69 6.36 5.95 5.66 0.06 Daily VMT 34.01 32.97 32.16 49.76 57.25 58.05 54.38 1.34 Per trip Average person trip length (miles) 9.67 8.87 8.68 9.47 9.13 10.04 9.75 0.36 Average vehicle trip length (miles) Read the entire page →
From page 41... ... Adapting Trip-Based Models to Address CAVs 41 Land Use Modeling Context A land use/demographic allocation process is usually added prior to running the four-step trip-based modeling process. Linkage to the travel demand process, if it is done, uses measures of accessibility derived from the trip tables and roadway/transit networks. Read the entire page →
From page 42... ... 42 Updating Regional Transportation Planning and Modeling Tools to Address Impacts of Connected and Automated Vehicles used (logsums from the mode choice step) Read the entire page →
From page 43... ... Adapting Trip-Based Models to Address CAVs 43 trips may be generated with reduced trip lengths. The ability to work closer to home and other daily activities may spawn increased work trip rates as the alternative workplace option competes with telecommuting. Read the entire page →
From page 44... ... 44 Updating Regional Transportation Planning and Modeling Tools to Address Impacts of Connected and Automated Vehicles from the lack of availability of vehicles exists. Changes in ownership patterns under CAV scenarios indicate the need for a different schema to address vehicle availability and its indication of modal preference and ease of trip generation. Read the entire page →
From page 45... ... Adapting Trip-Based Models to Address CAVs 45 Trip Generation Context Trip generation is the process used in trip-based travel demand models to estimate and forecast the number of trip ends generated by residential or commercial activity in TAZs. Trip ends refer to each end of a single trip: the origin or the destination. Read the entire page →
From page 46... ... 46 Updating Regional Transportation Planning and Modeling Tools to Address Impacts of Connected and Automated Vehicles technically cumbersome and work culture unsupportive, trip rates per worker could increase. The increase in trip making would be from fewer persons working, shopping, or completing other activities at home. Read the entire page →
From page 47... ... Adapting Trip-Based Models to Address CAVs 47 children may be able to call a CAV and be transported independently to and from school or other activities. These trips may add to vehicle trip generation. Read the entire page →
From page 48... ... 48 Updating Regional Transportation Planning and Modeling Tools to Address Impacts of Connected and Automated Vehicles from feedback loops from the traffic assignment step to reflect the effect of congestion resulting from inefficient networks. These inefficiencies could be reduced with CAVs. Read the entire page →
From page 49... ... Adapting Trip-Based Models to Address CAVs 49 by either auto or transit. Within the transit nest, several access mode options exist, including walking, driving, park-and-ride, and drop-offs, and SAVs. Read the entire page →
From page 50... ... 50 Updating Regional Transportation Planning and Modeling Tools to Address Impacts of Connected and Automated Vehicles for ownership of either CAVs or manually operated vehicles for trips with destinations in downtowns and dense areas of the city. If an environment of MaaS comes about in the future, modelers may want to consider the composite impact of multimodal tours rather than individual modal options for each trip in the mode choice step. Read the entire page →
From page 51... ... Adapting Trip-Based Models to Address CAVs 51 network. Gains from reduced crash rates would improve reliability and trip plans. Read the entire page →
From page 52... ... 52 Updating Regional Transportation Planning and Modeling Tools to Address Impacts of Connected and Automated Vehicles of capacity-enhancing operation. Traffic assignment modeling of capacity improvements from CAVs in a static UE assignment procedure requires relatively simple change to link capacity. Read the entire page →

From page 38...

... 38 This chapter presents critical considerations related to accounting for CAVs in trip-based models. Along with the subsequent chapters on disaggregate/dynamic models and strategic models, Chapter 6 provides the context for the modeling adaptations and then an approach for implementing them.