Crate sim[−][src]
The sim crate runs a traffic simulation on top of the map_model. See also https://a-b-street.github.io/docs/tech/trafficsim/index.html.
The simulation is very roughly layered into two pieces: the low-level “mechanics” of simulating individual agents over time, and higher-level systems like TripManager and TransitSimState that glue together individual goals executed by the agents.
Helpful terminology:
- sov = single occupancy vehicle, a car with just a driver and no passengers. (Car passengers are not currently modelled)
Modules
| analytics | |
| events | |
| make | Everything needed to setup a simulation. https://a-b-street.github.io/docs/tech/trafficsim/travel_demand.html for context. |
| mechanics | |
| pandemic | An experimental SEIR model by https://github.com/omalaspinas/ glued to the traffic simulation. Transmission may occur when people spend time in shared spaces like buildings, bus stops, and buses. |
| recorder | |
| render | Intermediate structures so that sim and game crates don’t have a cyclic dependency. |
| router | For vehicles only, not pedestrians. Follows a Path from map_model, but can opportunistically lane-change to avoid a slow lane, can can handle re-planning to look for available parking. |
| scheduler | |
| sim | |
| transit | |
| trips |
Structs
| AgentProperties | |
| Analytics | As a simulation runs, different pieces emit Events. The Analytics object listens to these, organizing and storing some information from them. The UI queries Analytics to draw time-series and display statistics. |
| BorderSpawnOverTime | |
| CarID | |
| CommutersVehiclesCounts | The number of active vehicles and commuters, broken into different categories. |
| CreateCar | |
| CreatePedestrian | |
| DistanceInterval | |
| DrawCarInput | |
| DrawPedCrowdInput | |
| DrawPedestrianInput | |
| ExternalPerson | |
| ExternalTrip | |
| IndividTrip | |
| MapBorders | Lists all border intersections of the map, broken down by mode and whether they support incoming or outgoing traffic. |
| OrigPersonID | |
| ParkedCar | |
| PedestrianID | |
| Person | |
| PersonID | |
| PersonSpec | |
| Scenario | A Scenario describes all the input to a simulation. Usually a scenario covers one day. |
| ScenarioGenerator | |
| SidewalkSpot | |
| Sim | The Sim ties together all the pieces of the simulation. Its main property is the current time. |
| SimFlags | SimFlags specifies a simulation to setup. |
| SimOptions | Options controlling the traffic simulation. |
| SlidingWindow | A sliding window, used to count something over time |
| SpawnOverTime | |
| TimeInterval | |
| TripID | |
| TripInfo | |
| TripPhase | |
| UnzoomedAgent | |
| Vehicle | |
| VehicleSpec |
Enums
| AgentID | |
| AgentType | |
| AlertHandler | |
| AlertLocation | |
| CarStatus | |
| DelayCause | Why is an agent delayed? If there are multiple reasons, arbitrarily pick one – ie, somebody could be blocked by two conflicting turns. |
| DrivingGoal | |
| ExternalTripEndpoint | |
| Intent | Shows an agent’s current inner intention or thoughts. |
| ParkingSpot | |
| PedCrowdLocation | |
| PersonState | |
| Problem | |
| ScenarioModifier | Transforms an existing Scenario before instantiating it. |
| SidewalkPOI | Point of interest, that is |
| TripEndpoint | Specifies where a trip begins or ends. |
| TripMode | |
| TripPhaseType | |
| TripPurpose | Lifted from Seattle’s Soundcast model, but seems general enough to use anyhere. |
| TripResult | |
| VehicleType |
Constants
| BIKE_LENGTH | |
| BUS_LENGTH | |
| FOLLOWING_DISTANCE | At all speeds (including at rest), cars must be at least this far apart, measured from front of one car to the back of the other. |
| LIGHT_RAIL_LENGTH | |
| MAX_CAR_LENGTH | |
| MIN_CAR_LENGTH | |
| SPAWN_DIST | When spawning at borders, start the front of the vehicle this far along and gradually appear. Getting too close to EPSILON_DIST can lead to get_draw_car having no geometry at all. |
Traits
| SimCallback |
Functions
| fork_rng | Need to explain this trick – basically keeps consistency between two different simulations when each one might make slightly different sequences of calls to the RNG. |