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Stop Models Design
Ben Stabler edited this page Apr 8, 2018
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The ActivitySim example model follows TM1's design with respect to modeling immediate stops on tours (i.e. trips). In TM1, tours are first attributed with an intermediate stop frequency and then a series of sub-models are run to convert the tours + number of stops to trips. After creating a skeleton panda's data frame of all trips based on the tours and stop frequency, the trip sub-models are processed in vectorized form by adding the necessary fields in order to subset and filter records as needed.
The new sub-models, which are inserted after atwork_subtour_mode_choice, are:
The existing create_simple_trips sub-model will be deleted since it was a simple placeholder for trips. The existing trip_mode_choice_simulate sub-model will be upgraded.
- For each tour
- MNL model by each purpose
- Alternatives: 16 (0 to 3 stops outbound + 0 to 3 stops inbound)
- Notes:
- This model should attribute each tour with a number of intermediate inbound stops and outbound stops
- This model should create a trip table for the subsequent sub-models with the following fields: household id, person id(s), tour id, and stop/trip tour sequence identifiers such as first_trip_on_tour_inbound, intermediate_trip_on_tour_inbound, last_trip_on_tour_inbound, etc. since these are required for subsequent model expressions and for a vectorized implementation. An inbound trip for a tour with no inbound stops would have first_trip_on_tour_inbound=true, intermediate_trip_on_tour_inbound=false, and last_trip_on_tour_inbound=true.
- For each intermediate stop on a tour (i.e. trip other than the last trip outbound to the tour primary destination or return home for the last trip inbound)
- Each stop is assigned a purpose based on an observed frequency distribution
- Notes:
- The distribution is segmented by tour purpose, tour direction and person type. Work tours are also segmented by departure or arrival time period.
- For each trip
- Select X alternatives using a similar recipe as before except for two major revisions:
- Condition the set of available alternatives by tour mode (for example, only alternatives that are within walking distance if the tour mode is walk-transit)
- Sequentially process the trips from tour origin to destination when outbound and then tour destination to origin when inbound. When doing so, the model calculates out-of-direction distance for the stop location in two-parts: origin to alternative destination location + alternative destination location to next destination.
- A new skim lookup key is required for this model. The existing
@odt,@dotkeys represent origin, destination, and time period. The@dptkey could be used to represent destination to primary destination for t, and@dhtkey could be used to represent destination to home for t. As a result, the out-of-direction distance trip destination choice would be@odt + @dptfor outbound and@odt + @dhtfor inbound. ?????
- Alternatives: Zones
- For each joint tour
- Calculate X mode choice logsums using the same recipe as work/school logsums for the sample
- Alternatives: Sample of alternative zones
- Notes:
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@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
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- For each joint tour
- Select a final destination zone using the same recipe as work/school logsums for the final choice
- Alternatives: Sample of alternative zones
- Notes: Use the Joint tour frequency model purpose to lookup the relevant destination choice model by purpose
- 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.
- For each joint tour
- MNL model that uses the existing expressions file - tour_mode_choice.csv
- Alternatives: Same as the other purposes
- Notes:
- The next step in this task is to complete the partially implemented trip mode choice sub-model by adding walk and bike alternatives, support for all purposes, using the correct OD pairs and time periods, using actual trips instead of tours, etc.