Monday, June 13, 2011

New Carrollton Fails to Stand Behind Optotraffic Cameras in Court

Rich Ladieu had challenged a speed camera citation before, and won, and was ready for another fight.  He had gotten a second citation from New Carrollton, and he had absolute proof he had not.  Rich has a device called a "carchip", basically a mini "flight recorder" which continuously records driving statistics, including speed, and it showed his maximum speed at the time of the March 8th 4:01pm citation was 32mph, not 50mph as shown on the citation.(View Data)

He got to court, but when the judge called his name, nobody from the city of New Carrollton had bothered to come and represent the prosecution.  The judge dismissed his case.

click to enlarge original citation image
Mr Ladieu in fact had prepared a rather excellent proof that the camera, built by Optotraffic/Sigma Space Corporation, was in error.  In addition to the log file from his CarChip, Mr Ladieu also had a composite image similar to those which had been done in the case of reported Forest Heights errors.

Mr Ladieu has stated that his truck is 16 feet long.  Our composite image shows a distance traveled of one truck length PLUS about 3 feet.  Based on that we can estimate a distance traveled of roughly 19 feet.  Given the formula of
   MPH = (Ft Traveled/.4s) * (3600s/hr) / (5280 ft/hr) = 32.5mph
This confirms the speed measurement from the carship, indicating the speed on the citation was off by eighteen mph!  For the speed on the citation to be correct, it would have needed to travel over 29 feet in .4s, which would have been almost 2 full vehicle lengths.  The distance from front-to-front in the images above is nowhere near 2 vehicle lengths.



Now granted, we only have 2 decimal places of precision on the timestamps, which does mean there is some variance in the actual time between frames.  And that is very very curious, because citation images we receieved from new Carrollton back in December 2009 (in a place where the speed limit was the same, 30mph), specifically showed a timestamp with 3 decimal places of precision, and a specific "delta time btw frames"
So why did Optotraffic change this?  It is strange, because the same change was made to Optotraffic cameras in Forest Heights and Cheverly... in both towns the citations USED TO show time accurate to 3 decimal places and give a delta time bw frames, but then the precision on the timestamps was reduced to 1 decimal place shortly after citizens in Cheverly and Forest Heights began using image timestamps to prove the cameras were producing errors.  The cynical answer to this (or should we say the REALISTIC answer to this), is that Optotraffic did this in order to make it harder to prove errors, attempting to deny citizens information they needed to prove their innocence.

When those complaints were first leveled in those towns, none of the explanations from either Optotraffic or the towns was that the timestamps were not accurate.  But recently, after all their other explanations were shot down, they have tried to make that claim.  So we are expected to believe a scientifically precise piece of equipment that they claim their speed cameras are can measure speeds accurate to within a tiny fraction of a MPH, but cannot produce an accurate timestamp.  

But this time we are in luck and can put that to the test.  In addition to the fact that Mr Ladieu's carchip recorded a speed pretty darn close to what our calculations produced, there is also a SECOND VEHICLE in the image, going the opposite direction.  Look at the image below, and compare the distance traveled by the pickup truck and the other car. 

The yellow and red lines show distance traveled by Mr Ladieu's pickup, the blue and green the distance shown by the compact car.  If Mr Ladieu's  pickup had in fact been traveling 20mph over the limit, we'd expect it should have been going faster than the prevailing speed of traffic.  Yet the Nissan Versa(?) appears to have traveled FARTHER (just under 2 lengths) than the pickup (slightly more than 1 vehicle lengths) in the same time interval, meaning it was moving FASTER.  So either the other car was traveling even faster than 20mph over the limit, which seems an unlikely coincidence, or this pickup truck was traveling at the prevailing speed of traffic... nowhere near 12mph over the limit, let alone 20.

Unfortunately, most people who get speed camera tickets simply assume the devices are accurate, that the technology is proven and reliable.  However Optotraffic's cameras do NOT work the same way as traditional police radar or police LIDAR.  It is a proprietary design which is NOT on the IACP's list of conforming law enforcement products, nor is their even any product which functions remotely the same way on that list.  Yet Maryland law permits it to be used to issue tickets, and to be the basis for finding people guilty.... that is if the prosecution has enough confidence in their speed cameras to show up and face a well prepared defendant in court.

It has even been videotaped that the sensors on Optotraffic's cameras are mounted on a 32 foot tall pole which will visibly sway in a wind of no more than 4-9mph, just a light breeze.  No amount of laboratory testing is going to tell them whether this device is still reliable while it is in motion.  If this movement were to cause the sensor frame to bend, even an infinitesimal amount, the beams could become 'cross-eyed', shortening the distance between the beams and producing an incorrect speed reading.  In addition, we note that many of the reported errors have been with pickup trucks (including this one), or other large vehicles such as buses or RVs.  Because these vehicles have higher ground clearance than most cars, an undershoot error is possible, as was described on the skeptical juror blog.  That would subtract the distance between the front of the truck and the tire from the distance between sensors, substantially overestimating the speed.

An interesting thing about this type of error is that it would tend to "favor" certain types of vehicles, since they have different profiles and ground clearances, and also certain drivers, who because of their personal driving habits tend to be a bit more to one side of the road than the other.  In fact if you look at Mr Ladieu's photos above, you will see that his vehicle is far to the right side of the lane, preparing to make a turn.  If the sensor beams are targeted at the CENTER of that lane, and undershoot error would actually be HIGHLY LIKELY in this instance.  Of course, most people who get camera tickets do not have CarChips, and would not be able to double check the recorded speed in the way Mr Ladieu did, or even think to do so.

Optotraffic has claimed nobody has ever shown them proof of an error.  I'd say we've just done exactly that. We have also provided a plausible mechanism for the error, and we have disproved any claims by Optotraffic that the image timestamps cannot be relied on to estimate vehicle speed.

The question is, why have Maryland lawmakers allowed Maryland to become the "beta test site" for unproven technology by having inadequate standards for testing and no oversight?  And when will Maryland officials take this matter seriously and put a stop to legalized fraud?