Best Technical Way to Prevent Accidents Using Speed Checker System

Death is something which is inevitable. But what about sudden death just because of some accident on the road or more worst- an injury which can screw up a person’s life for ever. Doesn’t it send a shiver down your spine, just by thinking about it? What is the major reason behind the accidents? Of course reckless driving and rash driving of vehicles especially on a smooth road like on high way.

According to statistical report, in the year span of 2005-2009, about 1200 deaths were due to accidents because of rash driving. And what more, you can get to hear news of accidents due to rash driver almost daily.

So, is there any way to prevent it? Of course!

There can be number of ways like being a good driver and following traffic rules, maintaining a normal speed. But there is one important way and that is keeping a vigil on the vehicle’s speed and accordingly monitors it.

This can be done technologically by devising a way to check the vehicle’s speed.

2 Ways to Check Speed:

  • Installing speed sensors on the road side or on the center of the road.
    • Incorporating video image processors: It consists of a camera installed on the poles of    roadsides, which constantly monitors the situation by taking images in quick succession of frames. The traffic flow parameters are analyzed and processed accordingly in a signal processor.
Image showing Traffic Monitoring by Video Camera
Image showing Traffic Monitoring by Video Camera
    • Incorporating RADAR on the lanes: A RADAR can be used to check the vehicle’s speed by sending a signal in microwave band towards the vehicle and analyzing a shift in frequency of the reflected signal. RADAR stands for Radio Detection and Ranging. The transmitted signal can be a signal with constant frequency or changing frequency. Normally a CW Doppler RADAR is deployed on the pole of the road side.
Speed Detection using RADAR
Speed Detection using RADAR
    • Installing IR sensors: IR sensors with a combination of IR LED and Photodiode can be used to monitor the distance travelled by the vehicle and simultaneously calculate its speed. The basic idea involves placing a pair of IR LED and photodiode at frequent intervals, on either side of the roads and monitoring the interruption of the path between the IR LED and the photodiode by the vehicle.

Here is a simple prototype of the above method. The sample prototype works with two pairs of IRLED-photodiode.

A Prototype circuit of Speed checking using IR sensor
A Prototype Circuit of Speed checking using IR Sensor by Edgefx Kits

             It consists of the following sections:

  1. A Photodiode- LED pair to sense the vehicle
  2. A counter to count and display the time taken by the vehicle to cross the path between the two photodiode-led pairs.
  3. A buzzer to indicate if the speed is above the set limit.
  4. Timer ICs to provide the signals at appropriate timing.
  • Using LIDAR gun: A LIDAR is a LASER based detection and ranging system. The traffic policeman can carry a portable LIDAR gun which sends a short burst of infrared light and as this light is reflected back by the moving vehicle, the gun makes an account of the time taken by the reflected signal and that is divided by two to measure the distance. Speed is measured by dividing the number of samples by fixed time duration of a few seconds. It works similar to a RADAR system except that it uses light waves instead of radio waves.
A LIDAR gun at the hands of a traffic policeman
A LIDAR gun at the Hands of a Traffic Policeman

Working of Speed Checker System using IR Sensors

Block Diagram showing the working of speed checker system using IR sensors
Block Diagram showing the Working of Speed Checker System using IR Sensors by Edgefx Kits

When a vehicle crosses the path between the first pair of IRLED-Photodiode, it blocks the way of light and the photodiode resistance increases, causing a corresponding low signal output to the timer IC1. The timer IC1 produces a high signal at its output for a fixed duration of 10ms. In normal conditions, at normal speed, there will be no interruption in the path between the 2nd Photodiode-IR LED pair and the corresponding input to the timer IC2 will be high, causing a low logic signal at its output. The outputs from both the timers are connected to NAND gate 2m which gives a high output (for low and high inputs), connected to the input of timer IC3. The corresponding output of the timer IC is low, causing the buzzer to be in off condition. In the same time, the output from the timer IC1 is given to both inputs of NAND gate1, which gives a low logic output which is given to timer IC4 to give a high logic output, connected to the reset pin of timer IC5. The output of timer IC5 is correspondingly high, giving high pulse to the counter IC. The Counter section consists of a 4 stage Decade Counters to read multiple digit count. Each counter IC clock is connected to the clock output of the previous counter IC. The Counter increases its count at each rising edge of the clock pulse.

Now suppose the vehicle is moving at such a high speed that it reaches the path between the second IRLED-photodiode pair in the time duration set for the timer IC1. So, now the counter will show a count below the normal count and in the same time, since NAND gate2 will get high at both its inputs, its output goes low and correspondingly the timer IC3 receives low input to give a high logic output and accordingly trigger the buzzer alarm.

Thus the distance between the two pairs divided by the counter reading gives the speed of the vehicle and if this speed increases the given limit, the buzzer rings giving a clear indication that the speed limit is violated.

I have given a detailed explanation of one of the ways. Any other ways are welcome to be given as feedback.

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