Traffic Radar procedure question

[Imagebuffet]

Originally Posted by CallMeAl

This wasn't asked, but I thought I'd throw it out there for information purposes.

The radar units are routinely calibrated and checked. Since tickets from radar/speed enforcement contribute greatly to a city's budget, they seldom skimp on this area. If you intend to challenge a ticket based on the maintenance records of the radar unit and/or it's calibration, be prepared to show the maintenance records / record of calibration for your vehicle. Usually, people say they weren't going the accused speed based on their speedometer. I don't know about you, but I've never had my speedometer checked or calibrated. Keep that in mind if you intend to use that defense.

Some states require speedometer checks as part of the annual inspection. I don't doubt that Texas does, though I recall that they used to run my car at 25 mph or whatever while testing emissions.

Imagebuffet added 1 Minutes and 29 Seconds later...Double Post Merged Below

Originally Posted by janikphoto

In theory, it shouldn't affect the end result. I'm not LEO, but I understand physics. The speed is determined by calculating the difference between two beams within a preset amount of time. Both beams would've been shot through the mirror, so there would be no variance.

Mirrors distort light waves. Every reflection adds distortion to the beam. At some point, it would make a difference in the read-out. Who knows where? It might be accurate, or it might not.

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Originally Posted by hooligan

You can use a traditional RADAR, k band, ka band....and use the reflective ability of the mirror to get a speed off of a car behind you. All LIDAR (lazer) units have some kind of red dot aiming device that you must look through. I have never even tried the lazer in a mirror. i do know that the type we use, you can not shoot through glass.

That sounds like they use an IR beam. Quite a bit of the IR spectrum doesn't go through glass so well.

Originally Posted by hooligan

Back in the day when all we had were hand helds, we used to use the mirror all the time. We were even shown in training with a second unit that the speed reading was accurate. It is not useful for lots of traffic behind you unless there is one obviously faster vehicle in the front of the pack.

Unless the mirror were certified to meet the radar manufacturer's performance specs, I would be leery of the results.

Incidentally, I have an AAS degree in Laser Electro-Optic Technology. My knowledge is rusty, but I still recall some basic things. One of them is that it is impossible to use a conventional back-surface mirror to make a helium-neon laser beam, because the mirror simply absorbs too much of the beam.

[acymc]

The answer is that the mirror technique is not an accepted practice as defined in the dept. policy or guidelines. Most officers can estimate speed fairly well and can always find some reason to stop and/or ticket a driver that is driving faster than traffic flow. It might not hold up in court, but then a solid radar reading sometimes doesn't hold up in court. The officer was probably just experimenting with the radar gun.

[kamari]

In theory even if the mirror is distorted it should not produce a reading that is faster than what the driver is traveling. I work on a sophisticated laser device that gets bounced off of a half dozen mirrors before being sent out of the unit in order to achieve--well I'm not allowed to talk about that--but it shouldn't have an effect.

The laser pulses still travel x feet to the target and still bounces x feet back to the gun, irregardless of the redirect from the mirror. As long as the distortion is constant for the emitting and receiving beams I'm thinking there shouldn't be an issue.

[Imagebuffet]

Originally Posted by kamari

In theory even if the mirror is distorted it should not produce a reading that is faster than what the driver is traveling. I work on a sophisticated laser device that gets bounced off of a half dozen mirrors before being sent out of the unit in order to achieve--well I'm not allowed to talk about that--but it shouldn't have an effect.

The laser pulses still travel x feet to the target and still bounces x feet back to the gun, irregardless of the redirect from the mirror. As long as the distortion is constant for the emitting and receiving beams I'm thinking there shouldn't be an issue.

I'm wondering if a mirror defect might generate a side node that could pick up something extraneous? Or, if an interference pattern might be generated in the beam (or, are they able to compensate?).

[DEMDeepEllumMusic]

Instead of 50mph you get .05 miles per hour.

[CallMeAl]

Originally Posted by acymc

Most officers can estimate speed fairly well and can always find some reason to stop and/or ticket a driver that is driving faster than traffic flow. It might not hold up in court, but then a solid radar reading sometimes doesn't hold up in court. The officer was probably just experimenting with the radar gun.

When I worked the streets, during training we were tested on speed estimation and routinely estimate speeds within 2-3 mph. Radar is only used to confirm our visual speed estimation and tracking of the vehicle. It's just one of many things used to confirm and prove a person's speed.

[Imagebuffet]

Originally Posted by CallMeAl

When I worked the streets, during training we were tested on speed estimation and routinely estimate speeds within 2-3 mph. Radar is only used to confirm our visual speed estimation and tracking of the vehicle. It's just one of many things used to confirm and prove a person's speed.

That makes me wonder about my last speeding ticket. It was in East Plano, I think on Park Blvd. It's a wide, 4-lane street with curbside parking, so it's about twice as wide as a regular 4-lane street. The speed limit is 30 mph, even though it feels to me like a 40 mph street.

Last year, as I was rushing to keep an appointment, I made a left turn onto that street just as the traffic light turned yellow. After a few seconds, I noticed that my speed was about 40 mph, so I slowed down to 30. But, a motorcycle officer up at the school on Jupiter was monitoring traffic from the tree-lined median. I couldn't have seen him, even though I was driving in his direction; I assume he couldn't have seen me much better. He pulled me over and cited me for driving 42 (I think) in a 30 zone.

I've often wondered how accurately he could have measured my speed, considering the trees and other obstacles in the way? I was in violation for just a few seconds, too, so he didn't have very long to target me. As I was moving pretty close to directly towards him, his visual estimate of my speed probably wouldn't have been as accurate as it would have been if I were moving perpendicular to his position.

I have all this on video, as I was recording my drive at the time. One of these days, I might upload it to YouTube.

[CallMeAl]

Originally Posted by Imagebuffet

I couldn't have seen him, even though I was driving in his direction; I assume he couldn't have seen me much better. He pulled me over and cited me for driving 42 (I think) in a 30 zone.

I've often wondered how accurately he could have measured my speed, considering the trees and other obstacles in the way? I was in violation for just a few seconds, too, so he didn't have very long to target me. As I was moving pretty close to directly towards him, his visual estimate of my speed probably wouldn't have been as accurate as it would have been if I were moving perpendicular to his position.

Usually when choosing a radar spot, the officer will be located in a position where he can see you long before you see him if you see him at all. Think of the old WWII movies where the enemy planes attack with the sun to their back so you don't see them until it's too late.

Another thing is that the officer who stops you is not always the one who catches you on radar (for a lack of better terms). A lot of times, one officer will be using a radar and calling out your vehicle for other officers to stop down the road. And before anyone complains, yes that is legal.

Also, with the new LIDAR (laser) units, it's a very small beam and it can reach you from a long ways away. You can be picked out of a group of vehicles so it's a little different than K Band, etc.

But in your situation...who knows. Luckily, that's why we have courts.

[Imagebuffet]

Originally Posted by CallMeAl

Usually when choosing a radar spot, the officer will be located in a position where he can see you long before you see him if you see him at all. Think of the old WWII movies where the enemy planes attack with the sun to their back so you don't see them until it's too late.

Another thing is that the officer who stops you is not always the one who catches you on radar (for a lack of better terms). A lot of times, one officer will be using a radar and calling out your vehicle for other officers to stop down the road. And before anyone complains, yes that is legal.

Also, with the new LIDAR (laser) units, it's a very small beam and it can reach you from a long ways away. You can be picked out of a group of vehicles so it's a little different than K Band, etc.

Thank you for your thoughtful comments.

Originally Posted by CallMeAl

But in your situation...who knows. Luckily, that's why we have courts.

Not in Plano we don't. When I went to the courthouse, I found that I was given only 3 options, and contesting the ticket is not one of them. I could plead guilty; I could ask for deferred adjudication; or, I could ask for driver's ed. All of them cost about the same amount of money, made payable to the City. Seems like a racket.

[Brains]

It's a simple speed tax, when it all gets boiled down. The only purpose for stopping nearly 100% of speeders is to tap the revenue.

That said, it is truly a game of cat n' mouse on the roadways. Speeders get caught more often than not, because they're not adequately watching the road. It's not easy to hide a cruiser on most Texas roadways, so keep your eyes open and check your speed when you see something that indicates ol' Smokey might be up ahead ;)

[Imagebuffet]

Originally Posted by Brains

It's a simple speed tax, when it all gets boiled down. The only purpose for stopping nearly 100% of speeders is to tap the revenue.

That said, it is truly a game of cat n' mouse on the roadways. Speeders get caught more often than not, because they're not adequately watching the road. It's not easy to hide a cruiser on most Texas roadways, so keep your eyes open and check your speed when you see something that indicates ol' Smokey might be up ahead ;)

Plano is kind of a special case. It appears that they have been working overtime to collect extra revenue, a situation commented on in a newspaper article when it was noted that Plano's government is one of the wealthiest in Texas per capita. They even help patrol Central Expressway, even when they don't have any cruisers on it. One of my co-workers, for example, was ticketed for having an expired tag on his windshield. He wondered how the Plano officer on the frontage road was able to tell what his sticker said when his car was on the Expressway.

[CaptainTom]

Originally Posted by Imagebuffet

Plano is kind of a special case. It appears that they have been working overtime to collect extra revenue, a situation commented on in a newspaper article when it was noted that Plano's government is one of the wealthiest in Texas per capita. They even help patrol Central Expressway, even when they don't have any cruisers on it. One of my co-workers, for example, was ticketed for having an expired tag on his windshield. He wondered how the Plano officer on the frontage road was able to tell what his sticker said when his car was on the Expressway.

The registration stickers come in different colors ??

[kamari]

Originally Posted by Brains

It's a simple speed tax, when it all gets boiled down. The only purpose for stopping nearly 100% of speeders is to tap the revenue.

That said, it is truly a game of cat n' mouse on the roadways. Speeders get caught more often than not, because they're not adequately watching the road. It's not easy to hide a cruiser on most Texas roadways, so keep your eyes open and check your speed when you see something that indicates ol' Smokey might be up ahead ;)

I always said if police were "really" out to stop speeders that the city should just post signs along the highway detailing how much speeding fines run for particular brackets of speed. Ex:

0-10mph over, $235
10-20, $285
20-30, $335

I think the general population would comprehend that A LOT better.

Not easy to hide a cruiser??? I was actually thinking the exact opposite. Especially now-a-days since the LED bulbs can shrink the size of the light rack on top of the cruiser from those old big twirly-birds to a strip about an inch tall. Those doggone Tahoes are the worst. Park one of them babies on the side of the road and you don't know what it is till about 100 yards away...and even then it can still be tricky.

[CallMeAl]

For what it's worth. My philosophy, and it's probably why I'm not in patrol anymore, is that if it's all about safety, hiding behind a tree waiting to catch someone 5-10 mph over the speed limit...just raised the speed limit on that road by 5-10 mph. Wouldn't I get more people to slow down and drive the speed limit if I maintained a high visibility on the road?

I was given a special assignment to monitor a "notoriusly" dangerous intersection for red light runners one morning. After an hour, the supervisor asked me how many tickets I wrote. I told him none. "Well how many did you stop?" he said. I replied, "None. No one ran the light." He couldn't believe it. He went on to say, "Well, where were you sitting." "Right in the middle of that traffic island (which is clearly visible by everyone approaching the intersection). "No one is going to run the light with you sitting there!" he replied.

My response..."Wasn't that the whole point?" Obviously not.

[Digigeek]

Originally Posted by jeffro20

Whatever the case may be.....just beware if you travel I-20 (820 S. Fort Worth) along the Wichita Exit to I-35. They radar that stretch DAILY and I see somebody pulled over EVERY DAY. They work that stretch hard.

Don't forget about 287/820 between I20 and I30, especially in the evening drive home time. In the mornings and some afternoons, they like to hide behind the signs on the overpass at Sun Valley/287. Otherwise, they are parked in the center median just over the crest of the hills along the whole stretch.