# Is there any Low cost sensor or sensory circuit which can figure out the Traffic density in a Junction?

My idea is to implement Automatic and Dynamic Traffic Control System.

I want to get the Vehicles density that were stopped along in all the roads in a particular junction. I want to get the binary information. For ex: If I get 1111s that means it has the highest traffic. If I get 0001s that means it has very less traffic.

Something like this. I am Ok if I get the information in any other format. I can redesign my implementation.

Based on the information I will change the timings for each road to clear.

I have implemented the logic using a simple flash software. But I need to implement this on board for the demo purpose. The sensor should cost low. Or any other circuit from which I can get information is also very helpful.

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## 2 Answers

Existing systems use inductive proximity sensors buried in the road. Using this and integrating the output you could get overall traffic volume, but it would not give you instantaneous traffic density.

Since it sounds like you're doing some sort of model, I think installing wires embedded in the road-surface isn't to viable.

Your best bet, I would think, since it seems you need something that does not take significant installation is a webcam and OpenCV. I bet you could put together a system that counts the approximate numbers of cars at an intersection using a computer-vision system without too much trouble.

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One solution I see in use a lot is having rubber hoses stretched across the road surface. They are sealed at one end, and have a pressure sensor at the other end. By having one at the end of an intersection (counting the outflow) and having one as far back as plausible (counting the inflow) you can get a count of how many axles are waiting at that intersection. It could also be done with IR beams, similar to the entryway chimes at some stores.

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Its funny to think that it will count not the vehicles, but how many axles passed the spot. Reading wiki about railroad train Axle counter can humble any ordinary software/hardware guy on aspects of reliability and safety. –  user924 Nov 13 '10 at 2:36
True. I would think that axles would be a good metric, though. An 18 wheeler with 5 axles takes more space than a car with 2. –  Jesse Nov 13 '10 at 5:58
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