Actors

• Driver
• Ground traffic controller (some ground traffic controller functions may be initiated automatically by SCUFS)
• Police officer
• Government official
• System administrator  (some system administration functions may be initiated automatically by SCUFS)
• Clock (triggers scheduled operations)

Use cases

• Enter freeway (primary actor: driver)
  • Main success scenario
    • Driver approaches entry point
    • System verifies that vehicle has working SCUFS equipment
    • System determines vehicle type
    • Driver indicates desired exit
    • System validates exit request
    • System assigns a traffic opening suitable for the vehicle type
    • System accelerates the vehicle into the opening
  • Alternate flows
    • Vehicle does not have working SCUFS equipment
    • Driver's exit request is invalid
    • Vehicle's engine fails while accelerating
    • System detects an obstruction on the entrance ramp
    • System cannot assign a traffic opening because a traffic stop is in progress
    • System denies entry because the highway entrance is closed because of a VIP corridor
    • System denies entry because the desired exit will be closed when the user arrives because of a VIP
• Maneuver in an emergency (primary actor: driver)
  • Precondition
    • Vehicle is traveling under SCUFS control
  • Main success scenario
    • Driver sees road hazard
    • Driver presses brake sharply or moves steering wheel sharply
    • In-vehicle equipment releases the vehicle from System control
    • In-vehicle equipment notifies System of the release
    • System sets the vehicle's status to emergency maneuvering
    • System increases monitoring of the area and nearby vehicles
    • System slows down nearby vehicles
    • Driver passes the hazard safely
    • Driver indicates that the emergency is over
    • System returns to normal operation
  • Alternate flows
    • Vehicle hits the hazard and/or another vehicle and/or runs off the road; System initiates accident operation
• Change exit selection (primary actor: driver)
• Stop a vehicle (primary actor: ground traffic controller, acting for a police officer)
• Update weather data (primary actor: clock)
  • Preconditions
    • System administrator has configured the target as a source of weather data
  • Main success scenario
    • Clock initiates weather data update
    • System looks up communication medium and parameters for the target
    • System sets up communication with the target
    • System requests weather data
    • Target responds with weather data
    • System tears down communication with the target
    • System validates data received
    • System updates its weather model
    • System checks weather model for conditions that required state changes or automatic actions
  • Alternate flows
    • Communication setup fails
    • Target reports an error condition instead of sending weather data
    • Data received is invalid
    • System places an area in a hazardous-weather state, based on the updated model
    • System removes an area from a hazardous-weather state, based on the updated model
• Update road condition data (primary actor: clock)
• Update obstruction data (primary actor: clock)
• Report an accident (primary actor: driver)
• Slow traffic down (primary actor: ground traffic controller)
• Clear corridors to and from an accident site (primary actor: ground traffic controller)
• Request a corridor for a VIP (primary actor: ground traffic controller, acting for a government official)
  • Main success scenario
    • Government official calls the SCUFS control center
    • Traffic controller verifies the government official's identity
    • Government official requests a corridor
    • Traffic controller enters date, time, route and desired security level
    • System validates the request
    • System computes and saves corridor plans for the requested date and time
    • System confirms the request
  • Alternate flows
    • Traffic controller concludes that the government official is not authorized to request a corridor
    • Traffic controller concludes that the caller is impersonating a government official
    • System determines that the corridor request is invalid
• Clear a corridor for a VIP (primary actor: clock)
  • Preconditions
    • The corridor was previously requested and confirmed
  • Main success scenario
    • Clock initiates processing a saved corridor plan
    • System requests confirmation that the VIP is on schedule
    • Traffic controller confirms that the VIP is on schedule
    • System closes highway entrances along the corridor
    • System alters exit validation criteria to conform to corridor plans
    • System routes traffic off the corridor and onto planned alternate routes
    • System makes the corridor accessible to authorized police and government vehicles for non-controlled use
    • System switches to maximum road hazard monitoring along the corridor
    • VIP traverses the corridor
    • System returns to normal operations along the corridor
  • Alternate flows
    • The VIP is late
    • The VIP is early
    • A non-controlled vehicle enters the corridor
    • A controlled vehicle fails to leave the corridor (because of engine failure, sabotage, etc)
    • A road hazard is detected in the corridor
    • The VIP's vehicle stalls in the corridor
    • The VIP's vehicle is involved in an accident in the corridor

For use cases whose steps are not provided here, make reasonable assumptions about the functionality required. You may also assume other use cases not named here. If you do, please identify them in your design paper.

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