Freight Vehicle Parking#
Freight vehicles in POLARIS—covering both business-to-business (B2B) heavy-duty truck deliveries and business-to-consumer (B2C) last-mile e-commerce deliveries—use the parking system to model stop-level parking at pickup and delivery locations. Freight parking differs from personal vehicle parking in several key ways: it uses specialized facility types (loading docks and loading zones), parking is planned as part of a vehicle routing optimization, and vehicles may cruise for alternative parking or double-park when no legal spot is available.
The figure below illustrates the end-to-end freight parking flow across the three phases: tour planning (parking assignment), vehicle initialization (reservation), and simulation (park, cruise, or illegal parking at each stop).
Freight Parking Types#
Freight vehicles use dedicated parking facility types that are distinct from passenger vehicle parking:
Vehicle Type |
Preferred Parking Types |
|---|---|
Medium-Duty & Heavy-Duty Truck (B2B) |
Loading dock |
Light-Duty Truck (B2C) |
Loading zone, street parking, metered parking, and generic location-based parking |
Loading docks and loading zones are identified internally as freight-specific facility types. During network initialization, freight parking facilities are excluded from walk-link assignment (unlike passenger parking, which may have an associated walk link for multimodal access). Spatial searches for freight parking also differ: when a freight-specific search is performed, the R-tree query does not fall back to searching all parking types—it returns only the requested freight types.
Parking in Tour Planning#
Parking locations are identified during the tour optimization phase, before trucks are dispatched onto the network. This contrasts with personal vehicle parking, where parking choice happens closer to departure or en-route.
B2B Delivery Model#
For B2B shipments, parking is assigned at each pickup and delivery stop in the vehicle routing problem (VRP). The model searches for the nearest loading dock within the configurable distance threshold for each shipment location. These parking assignments are stored in a list that parallels the stop sequence in the truck tour model.
Each stop in the optimized tour carries its assigned parking facility. When the tour is scheduled for simulation, the parking location is attached to the freight activity (trip leg), enabling the freight vehicle to drive to and park at the correct facility upon arrival.
B2C Delivery Model#
For B2C e-commerce deliveries, parking serves a dual role: it is both the stop-level parking assignment and an aggregation key for grouping nearby delivery locations. The model searches for the nearest parking from a broader set of types—loading zones, street parking, meters, and generic location-based parking—reflecting the reality that last-mile delivery trucks often use curbside parking rather than dedicated loading infrastructure.
Nearby deliveries that share the same parking location are aggregated into a single stop in the VRP. This aggregation reduces the complexity of the routing optimization while preserving the spatial structure of delivery clusters. Service time at each aggregated stop includes both the intra-stop travel time (computed via a TSP solver over the individual delivery locations) and per-package dropoff time.
When no parking can be found for a delivery location, the system falls back to using the delivery link itself as the aggregation key. This ensures all deliveries are represented in the tour, even in areas with sparse parking infrastructure.
Parking During Simulation#
Once a freight vehicle is dispatched onto the network, parking events occur at each stop along its tour.
Arrival and Parking#
When a freight vehicle completes a trip leg and arrives at a delivery or pickup location:
If the leg has a pre-assigned parking facility (from tour planning), the vehicle attempts to park there. The vehicle is marked as parked and a parking record is created.
If no pre-assigned parking exists, or if the pre-assigned spot is unavailable, the vehicle cruises for nearby parking. The cruising search uses the same spatial index as passenger vehicles, querying for the nearest available parking of the appropriate type within the distance threshold.
If cruising finds a spot, the vehicle parks there. A small cruising time penalty is added to the dropoff duration based on the distance to the found parking (estimated at 30 mph travel speed).
If no parking is found at all, the vehicle records an illegal parking event. An illegal parking counter on the vehicle is incremented. The vehicle proceeds with its delivery without formally parking.
Reservation During Initialization#
During freight vehicle initialization, the vehicle attempts to reserve parking at each leg’s assigned facility for the leg’s start time and anticipated dropoff duration. If the reservation fails (the facility is full for that time window), the parking assignment is cleared, and the vehicle will need to cruise for parking upon arrival.
This reservation step runs sequentially through all legs of the tour in chronological order, ensuring that time-overlapping reservations at the same facility are properly handled by the capacity management system.
Departure and Unparking#
Before starting the next leg of the tour, the freight vehicle unparks from the previous leg’s parking facility. The unparking operation finalizes the parking record (recording exit time and cost) and pushes it to the demand database. The vehicle then proceeds to its next origin link and begins the next trip leg.
Interaction with EV Charging#
For electric freight vehicles, parking events at delivery stops and depots are coupled with charging opportunities:
Depot charging: When the truck returns to its depot, it charges for up to the available dwell time.
Dock charging: At B2B delivery locations, the truck charges during the dropoff duration.
En-route public charging: If pre-planned during tour generation, the truck may also charge at public stations along its route.
Charging events at parking stops are recorded separately in the EV charging records table but are temporally and spatially co-located with the freight parking event.
Output and Analysis#
Freight parking events are written to the same Parking_Records table as passenger vehicle parking. The Is_TNC_Vehicle flag is false for freight vehicles, but freight parking can be identified by cross-referencing with the freight trip records or by filtering on freight-specific parking types (loading docks and loading zones).
The illegal parking counter on each freight vehicle provides an aggregate measure of parking supply inadequacy for freight operations in the simulated network. This metric can be used to evaluate the impact of curbside management policies, loading zone placement, and urban freight infrastructure investments.