When it comes to driving a car, one must always be on alert for possible obstacles and other drivers in the next lane over for changing lanes. But because older vehicles that lack built-in blind spot detection or parking sensors would require quite pricey upgrades, Redditor cisco_s_spedgang decided to make a DIY distance sensing system for far cheaper.

The idea was to take a total of six HC-SR04 ultrasonic sensors and place them around a vehicle, with two on either side, one at the front, and one at the back. From here, the connected Arduino Uno gets the distance measurements and performs several checks based on the resulting values as well as show a corresponding red LED for when the car gets too close to something else. Upon hitting the turn indicator stock for signaling a lane change, the blind spot assistance system will see if there is another vehicle on the same side as the turn signal and sound a loud alarm if it’s unsafe to cross over.

In its current form, this Arduino-based setup relies on a series of wires that span the entire length of the car, although cisco_s_spedgang does plan on tidying things up in the future. To see more about how this project works, you can read its post here on Reddit.