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Speed Camera Rules Vary, And Are Changing

I promised readers during Monday's online discussion that I would publish some of their questions and comments that I couldn't get to during the chat. One of our topics was the speed camera bill that cleared the Maryland General Assembly, and it drew this comment:

Speed camera web.jpg Speed enforcement camera eyes Wayne Avenue in Montgomery County. (Thomson)

"I never liked Speed Cameras: Mostly because of my aversion to Big-Brotherism. But I do think they're unfair to a degree. First, they are obviously a sea change in driving and traffic enforcement which to me means that the rules of the game should be defined. I think that it should be publicly available knowledge as to what speed triggers the camera. And I don't mean 'Oh, everyone knows it's 10 mph or more.' And ultimately I see no reason why it shouldn't be the posted speed limit.

Back to me: The programs work differently depending on who passed the law. In the District, drivers can get a ticket for any speed over the limit. D.C. police won't say how the cameras are set. When Maryland passed the pilot program now operating in Montgomery County, the law was written more conservatively.

The cameras could be placed only in residential areas or in school zones where the speed limit is 35 mph or lower. Signs must warn that cameras are in use. The fine was set at $40, and the money has to go for traffic safety. A vehicle had to be going more than 10 mph over the speed limit to draw a citation. (So you have to exceed the posted speed limit by about a third.)

The new Maryland bill, SB 277, authorizes camera use statewide but imposes some of the same restrictions. It raises the bar on speed so that a driver now will have to be going more than 12 mph over the limit to get a citation. Camera use in school zones will be limited: They may operate from 6 a.m. to 8 p.m. weekdays.

To address the commenter's concerns: The rules of the game are, If you're driving above the posted speed limit, you're speeding, which is against the law. Anybody who has a driver's license is supposed to know that. But people are breaking the law because they know they'll usually get away with it.

The Maryland law will let people get away with it, up to 11 mph over the speed limit. That's got less to do with law enforcement and safety than with politics.The cameras are controversial, because drivers don't like to get caught breaking the law. So the bill's path to passage included this big buffer. A case could be made to tighten that, but it will have to wait for another year.

By Robert Thomson  |  April 15, 2009; 6:54 AM ET
Categories:  Driving  
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Then perhaps you would care to explain why many roads are speed-limited with the idea that people will in fact speed (by about 10 mph over, actually)?

I seem to recall the argument against moving the speed limit on local highways up to 65 mph a few years back being, "People will just go 75 and not get caught." The argument *for* it was "the speed limit is 55 and traffic is already moving at 65, so make the 65 legal."

So which is it? Is 35 mph the actual safe speed limit, or could people actually reasonably, safely go 40 or so (Conn Ave S, between the Beltway and Chevy Chase for instance), but the speed limit is set at 35 so that they'll only realistically go about 45 (and people who go 35 or less are actual impediments to traffic)?

Posted by: | April 15, 2009 9:25 AM | Report abuse

One reason speed cameras around the world are rarely set to the exact speed limit--and one reason cops normally allow you a bit of tolerance when they're out with the radar/lidar--is that many cars' speedometers are slightly off. That is, your speedometer might read 35 mph when you're actually going 40. Or it might read 40 mph when you're actually going 37, although for obvious reasons a low-reading speedometer is a bigger concern. Most drivers with inaccurate speedometers have no idea that they're not seeing an accurate reading, and since the error normally isn't all that big (my 5-mph example is a bit more than you'd normally see) it makes more sense just to allow a cushion than it does to try to ticket everyone. (Of course, idiots who put the wrong size tires on their pimped-out SUVs with heavily tinted windows and big subwoofers will invariably have speedometer error due to the wrong-size tires, and I have no sympathy for them if they get tickets since it's their own fault that the speedometer read incorrectly.)

The Australian state of Victoria--the one where Melbourne is located--is an exception. The speed cameras there will issue a ticket if you're clocked at 3 km/h over the limit. That's a minimal tolerance and it's prompted a huge uproar amongst drivers there. 3 km/h is about 1.8 mph and it's very easy for your speedometer to be off by that small an amount. Even the cruise control on many cars can fluctuate by 3 km/h if you're on a hill.

Posted by: 1995hoo | April 15, 2009 9:32 AM | Report abuse

1995hoo is right. In fact, going back to my college engineering lab classes, every measurement has an amount of error or uncertainty. Each time you measure something you have to keep that error in your total measurement. So if your speedometer has an error and the radar gun has an error you have to add those errors together to get your full error bar. 10mph is probably sufficient to cover both those errors. That's why the gun's maintenance and calibration records are important.

What is annoying is that I once got a speeding ticket that seemed unbelievable. I went in to fight it and as soon as I said "not guilty" the judge threw the case out because the gun hadn't been calibrated properly and they knew it. Of course they should have known it before they mailed me a ticket and before I took an hour off of work to go down and fight the ticket. They would have been quite content to let me pay my $75 knowing that I was innocent and that is wrong.

But in general, I think speeding cameras are good things.

Posted by: cranor | April 15, 2009 10:03 AM | Report abuse

According to numerous studies, there is a natural speed that traffic will flow on any particular road, and that the speed of vehicles will tend to gravitate toward that speed, irrespective of the posted speed limit.

The National Motorists Association has posted a good FAQ on the subject with links to the relevant studies:

Posted by: afsljafweljkjlfe | April 15, 2009 11:39 AM | Report abuse

For those who are anti-cameras you may want to get a gps camera detector like

Posted by: macuser25 | April 15, 2009 12:16 PM | Report abuse

You people are placing a lot of faith in believing that the machines are 100% accurate and that the companies who run them are honest. There's a reason why the camera vendors never release data on how many erroneous citations are issued. If it's 1% it's way too high. An erroneous ticket leads to a loss of time, money, or both and is unjust.

Additionally, cameras have been proven to make roads MORE dangerous, not less. Learn more at

Posted by: photoradarscam | April 15, 2009 12:35 PM | Report abuse

Regarding inaccurate cameras, there was always the legendary Mini Cooper in Belgium that was clocked at Mach 3 by a speed camera. (For comparison, Concorde's top speed was Mach 2.02, or around 1,350 mph when flying at 60,000 feet.)

Posted by: 1995hoo | April 15, 2009 2:23 PM | Report abuse

It really doesn't matter to me whether it is 2mph over the limit or 20. Why is it that the cameras are "profitable"? The reason is simply that unlike human issued tickets the government doesn't need to pay anyone to take personal accountability for any individual ticket. Instead they can legally designate any "representative", who does not need to be a sworn police officer. If people challenge the tickets, that representative goes to court and when asked "was the machine operated/calibrated correctly" he can say "sure, they always are" even though they have no first hand knowledge of that instance. And the state never needs to worry about flaws in their procedures being revealed in court. That's a reduction in OUR legal rights which could bleed over into other things.

In some towns in Prince George's county, they are currently handing out red light camera tickets to people who come to a full stop just passed the line, and that these sorts of minor technical violations are the majority of red light tickets they are handing out. Now what is to keep these same authorities from putting up a "workzone camera" on a section of freeway where the speed limit has been lowered from 55 to 40 (with no workers required by the way), placing it 50 yards after the only 35mph sign, send thousands of tickets out after 14 days (30 days for out of state drivers) and remove the camera before any of the recipients find out how close to the sign it was? Who will guard the guards?

Posted by: afpre42 | April 16, 2009 6:41 AM | Report abuse

Just to add, with regards to my previous hypothetical situation, that Montgomery County has been asserting that they can legally place cameras as close as they want to a sign where there is a 10mph reduction in the speed limit, even if it's just a few tens of yards. It's easy to say "just obey the law" but I highly doubt that ANY driver (even Dr Gridlock) complies with it to that level of nit-pick detail.

Posted by: afpre42 | April 16, 2009 7:03 AM | Report abuse

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