Crate sim

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)

Re-exports

• pub use self::prebake::PrebakeSummary;

Modules

• analytics 🔒
• events 🔒
• make 🔒
  Everything needed to setup a simulation.
• 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.
• prebake
• 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
• ParkedCar
• PedestrianID
• Person
• PersonID
• 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. After parsing from structopt, you must call initialize.
• 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 🔒
• Intent
  Shows an agent’s current inner intention or thoughts.
• ParkingSpot
• PedCrowdLocation
• PersonState
• Problem
• ProblemType
• SidewalkPOI 🔒
  Point of interest, that is
• TripPhaseType
• 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

• count_parked_cars_per_bldg
• 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.
• pedestrian_body_radius
• rand_dist