Traffic Light Simulator | Visual Basic Sample Code

This traffic light simulator works like actual traffic lights and can be easily programmed using Visual Basic. The simulator demonstrates fundamental programming concepts like timers, conditional logic, and state management. This interactive version lets you experience how the traffic light works and see the corresponding Visual Basic code.

Traffic lights are a perfect example to demonstrate timer-based programming in Visual Basic. The program uses a timer to cycle through three states: green, yellow, and red. Each light stays on for a predetermined time before transitioning to the next state.

Interactive Traffic Light Simulator

The simulator follows a standard traffic light sequence: Green → Yellow → Red → Repeat. Each light stays on for 5 seconds except yellow which stays on for 2 seconds.

How the Traffic Light Works

The traffic light simulator works by cycling through three states using a timer:

Green Light

Indicates that traffic can proceed. This state lasts for 5 seconds.

Yellow Light

Warns that the light is about to change to red. This state lasts for 2 seconds.

Red Light

Indicates that traffic must stop. This state lasts for 5 seconds.

The program uses a timer to control the transitions between these states. The timer triggers an event at regular intervals, and in the event handler, the program checks the current state and switches to the next state.

Implementation Code

Below is the Visual Basic code for the traffic light simulator. We've provided both VB6 and VB.NET implementations:

VB6 Code

VB.NET Code

' VB6 Traffic Light Simulator
Private Sub Timer1_Timer()
    ' Check current state and transition to next
    If Shape1.Visible Then ' Green is visible
        ' Transition to yellow
        Shape2.Visible = True
        Shape1.Visible = False
        Shape3.Visible = False
    ElseIf Shape2.Visible Then ' Yellow is visible
        ' Transition to red
        Shape3.Visible = True
        Shape2.Visible = False
        Shape1.Visible = False
    Else ' Red is visible
        ' Transition to green
        Shape1.Visible = True
        Shape2.Visible = False
        Shape3.Visible = False
    End If
End Sub

Private Sub Form_Load()
    ' Initialize the traffic light
    Shape1.Visible = True ' Green
    Shape2.Visible = False
    Shape3.Visible = False
    
    ' Set timer interval to 5000ms (5 seconds)
    Timer1.Interval = 5000
    Timer1.Enabled = True
End Sub

In this VB6 implementation, we use three Shape controls (Shape1 for green, Shape2 for yellow, Shape3 for red). The timer event handler checks which light is currently visible and transitions to the next light in sequence.

' VB.NET Traffic Light Simulator
Public Class TrafficLightForm
    Private currentState As Integer = 0 ' 0=Green, 1=Yellow, 2=Red
    
    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        ' Turn off all lights
        GreenLight.Visible = False
        YellowLight.Visible = False
        RedLight.Visible = False
        
        ' Determine next state
        Select Case currentState
            Case 0 ' Green -> Yellow
                YellowLight.Visible = True
                currentState = 1
                Timer1.Interval = 2000 ' 2 seconds for yellow
            Case 1 ' Yellow -> Red
                RedLight.Visible = True
                currentState = 2
                Timer1.Interval = 5000 ' 5 seconds for red
            Case 2 ' Red -> Green
                GreenLight.Visible = True
                currentState = 0
                Timer1.Interval = 5000 ' 5 seconds for green
        End Select
    End Sub

    Private Sub TrafficLightForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ' Initialize the traffic light
        GreenLight.Visible = True
        YellowLight.Visible = False
        RedLight.Visible = False
        
        ' Start timer
        Timer1.Interval = 5000
        Timer1.Start()
    End Sub
End Class

In this VB.NET implementation, we use a state variable to track the current light state. The timer event handler uses a Select Case statement to determine the next state, making the code more maintainable and easier to extend.

Video Demonstration

Watch how the traffic light simulator works in a real Visual Basic application.

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