Friday, January 06, 2006

Smart traffic signals with WiFi + GPS to prevent red light running

Running over red light at a traffic signal is one of the serious causes of side-impact collisions. Today the only way to avoid such an accident is in the hands of the driver who approaches the signal. He has to be alert. If he does run over, he puts the cross traffic in grave danger. In a typical US express way, that amounts to a 40-55 MPH collision. The method described here alerts the driver about the state of the approaching traffic light.

I'm sure this idea would've been reached independently by others. With the advancement in WiFi and GPS, the solution is pretty simple and cost effective too.

A high risk traffic signal gets a WiFi transmitter and continuously broadcasts its state. The state could convey information like which roads are getting what light, how long before the light changes and other related information. It also sends its GPS coordinates. Any car within the WiFi range (which is about 300 ft) can know the state of the signal and can alert the driver if the speed is inappropriate. Note that the station (located at the traffic signal) does not really need a GPS receiver; since it is static, its location can be hard-coded.

The approaching car using its GPS knows if a particular signal is of interest (the approaching one). Without knowing which signal is of interest, the car can get signals from lots of stations in a crowded in-city kind of location.

Once the car learns about a signal state, it can alert the driver through visual/audio alerts. The overall cost is reasonable. The cost to install a transmitter at a signal is one time cost; it does not need to scale with the traffic. Note that the car does not talk to the station -- it is a passive receiver of information. Even a car without GPS can use the system; it's just that it may get some false positive alerts. The minimum the car needs is a WiFi listener.

A more futuristic version can enable the station to update its state in real-time to a central server. The car could talk to the server in real-time (using some other network connectivity, say the Internet) to get the signal state data using its current GPS coordinates (this eliminates the Wi-Fi).


At 9:53 PM, Blogger GPS Systems said...

Hi, Thanks for your interesting blog. Keep up the great work! I also have a site & blog about car gps, please feel free to visit.

At 12:00 PM, Blogger Karthik Gurusamy said...

gps systems,
That's a very comprehensive gps collection you have there. I'm going to read thru' some of the articles there. I'm wondering how small these devices can get.. like their power requirement.. I have some idea of their working ..listening to time signals sent by satellites and do triangulation. So that implies there is not much work happening at the gps wondering why they can't be too small. Any case I need to read up a little more on it.



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