First-Mile Last-Mile (FMLM)

First-Mile Last-Mile (FMLM)#

The first-mile last-mile (FMLM) module extends the functionality of normal shared mobility operations to include trips to/from bus stations and rail stations. A FMLM trip/trajectory can consist of multiple legs of walking, using an e-scooter, riding a taxi-like service, and riding transit. When a traveler takes an FMLM trip, the router finds the shortest path based on prevailing network conditions and using the average TNC wait time for finding a vehicle. During the execution of the route, these travelers request a TNC ride and the shared mobility operator finds a match to serve the ride. The FMLM functionality can be turned on for each Operator.

    "Operator_1": {
        "use_fmlm": true
    }

FMLM travel modes#

Trips in the simulation that have a combination of modes that represent a FMLM trip is logged with the mode type TNC_AND_RIDE. TNC_AND_RIDE is the mode where the bus or rail is the main component of trip travel time, and access or egress is done using a TNC vehicle. New mode types will be added for other combination of modes. For more information about how the FMLM mode is chosen from the mode choice model, please refer to the Mode Choice Theory.

Multimodal Routing#

Multimodal routing is used for modes involving transit and shared mobility mode segments. A multimodal route is calculated based on the multimodal shortest path, which is built based on the shortest link travel time from origin to destination, leveraging network links of any possible type (e.g., driving, walking, or transit links). Adjustments and penalties are also incorporated to ensure a reasonable multimodal path, including the number of transfers, walking time, and driving distance. Parameters in the MultiModalRouting.json can help tweak the quality of multimodal routes obtained during simulation.

"tncWaitCountThreshold": 2, # the total number of TNC legs that can exist in a multimodal trajectory
"transitWaitCountThreshold": 1, # the total number of transit transfers that can exist in a multimodal trajectory
"fmlmMinDriveTimeSeconds": 1800, # the minimum time that a TNC shortest path should take in the multimodal trajectory to make the trajectory more realistic as well as reducing the computation burden

For a better understanding of the multimodal router, please see the Multimodal Routing details.