Introduction: Automatic London Bascule Bridge (Arduino Based Student Project)

Hi Everyone! This Instructable shows you how to make an Automatic
London Bascule Bridge Model easily using Arduino UNO, IR sensors and Stepper motor. The structure of the model is made out of the acrylic sheet. We have used stepper motor and ropes for moving the bridge up and down, on passage of a certain body. Moreover, the uln2003a H-Bridge (electrical circuit) has been designed for controlling the direction of the motor (clockwise and anti-clockwise). Its 3-Dimentional model has been designed using the software “SOLIDWORKS”.

VideoURL: Click Here


For this project you will need:
1. Acrylic Sheets

2. 1 x Stepper Motor

3. 1 x IR sensor

4. 1 x Arduino UNO

5. PCB board if required

6. 1 x Stepper Motor Driver ULN2003A

7. Some Eye Screw Hooks or Pulleys

8. 2 x Door Hings

9. 10 x L Brackets

10. Ropes or threads

Step 2: Preparing Your Design in Solidworks (Mechanical Part)

I used Solidworks to Design the whole model. All the dimensions and figures are given in files.
Just download the files and open the them in the solidworks. :)

Step 3: Preparing Your Circuits (Electronics Part)

This step is also very easy. I used Proteus to make the Circuit. Connect every wire according to the schematic given in figure. I have also attached the Proteus ISIS file.

Unipolar and Bipolar Motors:

Different stepper motors can have different amounts of wires, typically 4, 5, 6, or 8 wires. Unipolar motors typically have five, six, or eight wire leads extending from the base and one coil per phase. In a six wire motor, the coil pairs each have their own center tap. The Unipolar can be converted into Bipolar configuration, the advantage of this is that Bipolar Stepper Motor can hold more load or torque as compared to Unipolar Stepper motor.Usually Bipolar Stepper motor have Four wires. For more detail and better information you can see these links.

1. Intro to Stepper Motors

2. How to use a Stepper Motor

Step 4: Software and Coding (Arduino IDE)

This is the final step, the hardware is finished and we can start programing. Open the arduino IDE software and copy the program below or download the Code.txt file. Connect you arduino Board via usb cable, check the COM PORT and then Compile and Upload the code to your Arduino connected to your system.


const int stepsPerRevolution = 200; // change this to fit the number of steps per revolution // for your motor

int sensorPin = A0;

int sensorValue = 0;
// initialize the stepper library on pins 8 through 11:

Stepper myStepper(stepsPerRevolution, 8, 9, 10, 11);

void setup()


pinMode(A0, INPUT);
myStepper.setSpeed(60); // set the speed at 60 rpm


void loop()


sensorValue = analogRead(sensorPin);
if (sensorValue >= 150) //Change the you according to your distance from the sensor


// step one revolution in one direction:



delay(2000); // you can change the delay time value depending upon your motor's revolutions

// step one revolution in the other direction:







Step 5: Finish :D

Thats the end of this Project. Hope you guys like it and thanks for watching :D
For Video Click here: London Bascule Bridge

Mind for Design

Participated in the
Mind for Design