globals [
  tick-counter   ; tracks simulation ticks
]

breed [ cars car ]
breed [ pedestrians pedestrian ]
breed [ traffic-lights traffic-light ]

cars-own [
  my-speed
  waiting-time    ; how many ticks this car has spent waiting
]

pedestrians-own [
  my-speed
]

traffic-lights-own [
  state           ; "green", "yellow", or "red"
  time-left       ; ticks left in the current light state
]

to setup
  clear-all
  set tick-counter 0
  setup-patches
  setup-traffic-lights
  reset-ticks
end

to setup-patches
  ask patches [
    if (pxcor = 0 or pycor = 0) [
      set pcolor gray
    ]
    if (pxcor != 0 or pycor != 0) [
      set pcolor green + 2
    ]
  ]
end

to setup-traffic-lights
  create-traffic-lights 2 [
    setxy 0 0
    set state "green"
    set time-left green-time
  ]

  let i 0
  ask traffic-lights [
    if i = 0 [ set heading 0 ]
    if i = 1 [ set heading 90 ]
    set i i + 1
  ]
end

to go
  spawn-vehicles
  spawn-pedestrians
  update-traffic-lights
  move-cars
  move-pedestrians
  enforce-road-capacity
  plot-stats

  tick
  set tick-counter tick-counter + 1
end

to spawn-vehicles
  if random-float 1 < (vehicle-entry-rate * 0.01) [
    create-cars 1 [
      let r random 2
      if r = 0 [
        setxy 0 max-pycor
        set heading 180
      ]
      if r != 0 [
        setxy min-pxcor 0
        set heading 90
      ]
      set color red
      set my-speed 1 + random-float 0.5
      set waiting-time 0
    ]
  ]
end

to spawn-pedestrians
  if random-float 1 < (pedestrian-arrival-rate * 0.01) [
    create-pedestrians 1 [
      setxy (random 3 - 1) (random 3 - 1)
      set color blue
      set shape "person"
      set my-speed 0.4 + random-float 0.2
    ]
  ]
end

to update-traffic-lights
  ask traffic-lights [
    set time-left time-left - 1
    if time-left <= 0 [
      let old-state state

      if old-state = "green" [
        set state "yellow"
        set time-left yellow-time
      ]
      if old-state = "yellow" [
        set state "red"
        set time-left red-time
      ]
      if old-state = "red" [
        set state "green"
        set time-left green-time
      ]
    ]
    if state = "green"  [ set color green ]
    if state = "yellow" [ set color yellow ]
    if state = "red"    [ set color red ]
  ]
end

to move-cars
  ask cars [
    let nearest-light min-one-of traffic-lights [ distance myself ]
    let waiting? false

    if distance nearest-light < 2 [
      if ([state] of nearest-light) = "red" and within-heading? self nearest-light [
        set waiting? true
      ]
      if ([state] of nearest-light) = "yellow" and within-heading? self nearest-light [
        if random 100 < 50 [
          set waiting? true
        ]
      ]
    ]

    if not waiting? [
      forward my-speed
    ]
    if waiting? [
      set waiting-time waiting-time + 1
    ]

    if (xcor > max-pxcor or xcor < min-pxcor or
        ycor > max-pycor or ycor < min-pycor) [
      die
    ]
  ]
end

to-report within-heading? [ a-car a-light ]
  let car-heading [heading] of a-car
  let light-heading [heading] of a-light

  if (abs (car-heading - light-heading) < 45) [
    report true
  ]
  if (abs (car-heading - light-heading) > 315) [
    report true
  ]
  report false
end

to move-pedestrians
  ask pedestrians [

    right random-float 30
    left random-float 30
    forward my-speed

    if pcolor = gray [
      ask cars in-radius 1 [
        set my-speed 0.2
      ]
    ]

    if (xcor > max-pxcor or xcor < min-pxcor or
        ycor > max-pycor or ycor < min-pycor) [
      die
    ]
  ]
end

to enforce-road-capacity
  ask patches with [ pcolor = gray ] [
    let car-count count cars-here
    if car-count > road-capacity [
      let excess car-count - road-capacity
      let sorted-cars sort-on [ who ] cars-here
      ;; stop extra cars for demonstration
      ;;ask first excess sorted-cars [
       ;; set my-speed 0
      ]
    ]
  ;
end

to plot-stats
  set-current-plot "Traffic Statistics"

  set-current-plot-pen "car-count"
  plot count cars

  set-current-plot-pen "avg-waiting-time"
  plot average-waiting-time
end

to-report average-waiting-time
  if any? cars [
    report mean [ waiting-time ] of cars
  ]
  report 0
end
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"" ""
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"car-count" 1.0 0 -16777216 true "" "plot count turtles"
"avg-waiting-time" 1.0 0 -7500403 true "" "plot count turtles"

@#$#@#$#@
## WHAT IS IT?

This model simulates traffic flow in Václavské náměstí (Wenceslas Square), Prague. It focuses on how factors such as traffic light timing, pedestrian crossings, and road capacity affect congestion and average travel time. The model aims to help city planners, engineers, and researchers experiment with different configurations to optimize traffic flow.

## HOW IT WORKS

The simulation uses multiagent modeling where vehicles and pedestrians interact dynamically within a grid representing the real-world layout of Václavské náměstí. Vehicles navigate toward destinations while adhering to traffic rules, stopping at red lights or yielding at pedestrian crossings. Pedestrians randomly move across crossings, influencing traffic flow. Traffic lights alternate between green and red phases, impacting vehicle movement.

Key behaviors include:

Vehicle Movement: Vehicles travel toward assigned destinations, stopping for red lights or pedestrians.

Pedestrian Behavior: Pedestrians cross roads randomly at designated crossings.

Traffic Light Logic: Lights switch between green and red at fixed intervals, creating stop-and-go conditions.

Congestion Calculation: Overall congestion is measured as the cumulative waiting time of vehicles.

## HOW TO USE IT

Setup the Simulation:
Use the SETUP button to initialize the grid, traffic lights, vehicles, and pedestrians.

Run the Simulation:
Press GO to start the simulation.
Adjust sliders during the simulation to modify traffic light duration, vehicle count, pedestrian density, or other variables.

Sliders and Controls:
Number of Vehicles: Total number of vehicles in the simulation.
Number of Pedestrians: Total number of pedestrians.
Traffic Light Duration: Time interval for light phases.
Pedestrian Arrival Rate: Probability of pedestrians arriving at crossings.

## THINGS TO NOTICE

Observe how traffic congestion builds at intersections during high vehicle or pedestrian density.
Notice the relationship between traffic light duration and average travel time.
Watch how pedestrian crossings slow vehicle movement and increase waiting times.
Identify patterns of flow in low versus high road capacity scenarios.

## THINGS TO TRY

Experiment with Traffic Light Timings: Adjust the Traffic Light Duration slider to test the effect of shorter or longer light phases on congestion.
Increase Pedestrian Density: Raise the Number of Pedestrians slider to see how high pedestrian activity affects vehicle travel time.
Vary Road Capacity: Simulate single-lane versus multi-lane road scenarios by changing the vehicle count.
Peak Hours Simulation: Combine high vehicle entry rates with frequent pedestrian crossings to simulate rush hour conditions.

## EXTENDING THE MODEL

Add adaptive traffic light logic to dynamically adjust light timings based on congestion.
Introduce specific rush hour scenarios with periodic spikes in vehicle entry rates.
Include specific vehicle types (e.g., buses or emergency vehicles) with unique behaviors or priority rules.
Model real-world pedestrian crossing behavior more accurately by introducing factors like jaywalking or group crossings.

## NETLOGO FEATURES

The model uses dynamic traffic-light patches to simulate real-world signal behavior.
Agent-based interaction between vehicles and pedestrians demonstrates complex traffic flow emergent from simple rules.
Sliders allow real-time adjustments to key parameters, making the simulation highly interactive and customizable.

## RELATED MODELS

Traffic Basic (NetLogo Models Library): A simpler model of traffic flow that could provide foundational insights.
Pedestrian Behavior (NetLogo Extensions): A model focusing on pedestrian dynamics.

## CREDITS AND REFERENCES

Data Sources:
City of Prague Open Data Portal
Traffic Congestion and Urban Planning
Effects of Traffic Signal Timing on Urban Traffic Flow
Pedestrian Impact on Traffic Flow Dynamics
Model Design: Inspired by real-world conditions at Václavské náměstí, Prague.
@#$#@#$#@
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