The Future of Speeding Tickets

Radar guns work by way of the Doppler Effect principle.  A signal is sent from the radar gun to the moving vehicle.  The signal reflects off of the vehicle and strikes the radar gun where it originated from.  The radar gun compares the received signal to the one it sent, and then, based on the frequency shift, computes the speed of the moving vehicle.  This very same principle is invoked to determine the relative velocity of distant stars based on the frequency shift of the light they emit.

When I first learned about the Doppler Effect and its application to handing out speeding tickets, I wondered why policeman were always stationary while using it.  After all, the devices measure relative velocity, so if the motion for the radar gun itself were accounted for, it could still compute the absolute speed of moving cars with sufficient accuracy.  For example, a radar gun could be mounted onto a police car, and have the vehicle's speedometer as an input - the device could then fire radio signals to cars behind and in front, receive the echo, compute the relative velocity, and then the absolute speed.  When I mention this to my students, they sometimes respond with, "Don't give the cops any ideas."

Most drivers can relate to the sinking feeling that accompanies a distant parked police car and a radar gun with us in its sights.  Even cautious drivers speed from time to time.  A buddy of mine actually refers to speeding tickets as "driving tax".  The speed monitoring system, as it stands, employs many policeman (I'd be curious to know the percentage) and brings in a healthy amount of money to city hall.  

Recent developments in recording speeds of distant vehicles (LiDAR speed guns, for instance) have raised the precision and range of the measurement instrument.  While such technologies may appear advanced, they are, in my opinion, not the optimal way to monitor speed and disseminate fines.

In today's GPS world, why pay thousands of policemen to monitor the speed of thousands of cars, one by one, when we could monitor the speed of all cars without aiming these silly guns at them?

In many cities, like Montreal, Quebec, for example, select locations are armed with cameras and other devices, which take pictures of the license plates of speeding cars, and send the ticket in the mail.  While this does not waste man-power like the traditional cop chase, which precedes the writing of a ticket (which, incidentally, is often more dangerous than the initial infraction was), it still does not take advantage of GPS technology.

Why use fancy equipment to monitor the speed of the vehicles at all?  We need not play spy.  All vehicles monitor their own speed: the instrument employed is called a speedometer.  If all cars simply had their own speedometer input to their GPS, the degree to which all cars were speeding would be known at all times.  I can just see the public lining up to purchase such a technology.

At first, necessitating constant speed monitoring for all cars at all times seems heavy-handed, totalitarian even.  But, is it really worse than the cat and mouse game that is our current solution for creating a safe driving environment?

If all cars were monitored at all times, then a more accurate, representative speeding tax could be applied to drivers.  Some drivers are better than others at spotting a hidden cop car lurking in the shadows.  Should this skill really be what separates drivers who pay for driving dangerously and those who do not?  With my admittedly big-brother approach to monitoring vehicular speed, we would all get a small ticket in the mail at the end of the month based on our personal propensity for speeding (OK, I'm not selling this idea very well here).

Seriously though, the total income to the city would be the same, the roads would be safer (that is the point isn't it?), and law enforcers could spend their time enforcing laws where a human presence is truly needed.

We are perhaps two or three decades away from driver-less roads.  Google is currently at work on this revolution in transportation.  Once this becomes the new norm, cars will never speed, and city hall will need to find a new way to tax their citizens - I have complete faith that they will succeed in doing so.

But, in the interim, while us imperfect drivers use our own judgement to safely navigate the roads, let's use the existing GPS technology to make road safety less of a game.  We can then use our rear view mirrors for their intended purpose, rather than periodically checking whether the cop car we just drove by is turning its lights on.