Joint Travel Design

In the current example model, joint travel for non-mandatory activities is modeled explicitly in the form of fully joint tours (where all members of the travel party travel together from the very beginning to the end and participate in the same activities along the way). This accounts for more than 50% of joint travel. Other types of joint travel like carpooling of workers and escorting children are not explicitly considered currently, though they are handled implicitly through shared ride alternatives in mode choice. Some later revisions to CT-RAMP in specific regions more completely model joint travel. For now, the example follows the MTC TM1 design.

The new sub-models are:

• Joint tour frequency
• Joint tour party composition
• Joint tour person participation
• Joint tour primary destination choice
  • Joint tour primary destination choice sample
  • Joint tour primary destination choice sample logsums
  • Joint tour primary destination final choice
• Joint tour time-of-day choice (i.e. scheduling)
• Joint tour mode choice

Joint tour frequency

• For each household
• MNL model with new expression file - joint_frequency.csv
• Alternatives: 21 (No Tours, 1 Tour segmented by purpose, 2 tours segmented by purpose combination)
• Notes: Includes the presence and size of overlapping time-windows, which represent the availability of household members to travel together after mandatory tours have been generated and scheduled.

Joint tour party composition

• For each joint tour
• MNL model with new expression file - joint_party_composition.csv
• Alternatives: 3 (Adults-only, Children-only, Adults + Children)
• Notes: Include the maximum time window overlaps across adults, children and adults or children after mandatory tours have been scheduled.

Joint tour person participation

• For each joint tour and person
• MNL model with new expression file - joint_tour_person_participation.csv
• Alternatives: 2 (Participate in joint tour or does not participate in joint tour)
• Notes:
  • Persons with CDAP=Home are excluded
  • Requires the calculation of available person time windows
  • The Java model loops through household persons until a valid tour party is formed. Within the valid tour party loop, a switch statement based on the party composition sets up and solves the relevant expression file for a) adults only, b) children only, or c) mixed, adults and children. After solving the relevant model, it checks for a valid party and if not, it then repeats the participation choice with new random numbers.
  • Vectorizing the model requires re-structuring the problem into a series of pandas tables with rows being joint tours and columns being explanatory variables, including those for each person potentially being added to the joint tour. This is a switch from a for loop within each tour to a for loop that operates on each potential joint tour party.

Joint tour primary destination choice sample

• For each joint tour
• Select X alternatives using the same recipe as work/school location sampling
• Alternatives: Zones
• Notes: Use the Joint tour frequency model purpose to lookup the relevant destination choice model by purpose

Joint tour primary destination choice sample logsums

• For each joint tour
• Calculate X mode choice logsums using the same recipe as work/school logsums for the sample
• Alternatives: Zones
• Notes:
  • @odt_skims - home taz, alternative taz, time period = Midday (MD)
  • @dot_skims - alternative taz, home taz, time period = Midday (MD)
  • Use the Joint tour frequency model purpose to lookup the relevant destination choice model by purpose

Joint tour primary destination final choice

• For each joint tour
• Select a final destination zone using the same recipe as work/school logsums for the final choice
• Alternatives: Zones
• Notes: Use the Joint tour frequency model purpose to lookup the relevant destination choice model by purpose

Joint tour time-of-day choice (i.e. scheduling)

• For each joint tour
• MNL model with new expressions file - tour_departure_and_duration_joint.csv
• Alternatives: tour_departure_and_duration_alternatives.csv (same as the other purposes)
• Notes:
  • Tour departure and arrival period combinations are restricted to only those available for each participant on the tour, after scheduling mandatory activities
  • Once the tour departure/arrival time combination is chosen, it is applied to all participants on the tour.

Joint tour mode choice

• For each joint tour
• MNL model that uses the existing expressions file - tour_mode_choice.csv
• Alternatives: tour_departure_and_duration_alternatives.csv (same as the other purposes)
• Notes:
  • Use the Joint tour frequency model purpose to lookup the relevant destination choice model by purpose
  • Makes use of some new expressions, such as is_joint and number_of_participants for example