I knew he was up there, somewhere close. All the signs were present: 18 wheelers were going 5 above the speed limit and Waze had a posting...so I slowed down to 70 and Boom..my Escort when off "K BAND" "RAP, RAP RAP..." just as I passed a bridge abutment on the Pennsylvania Turnpike just east of King of Prussia...I looked over and there he was holding a portable radar unit at a 45 degree angle to the road. He ignored me as he ignored the truck I was pacing immediately to my left.

My 8500ci worked but did not provide any, none, nada, warning of this roadside hazard. This is the second time I've noticed this on the turnpike...Anyone know if they are doing something different? Are they using a low power unit? Narrow beam?

This is just weird.

 

Were there any cars ahead of you for the radar to bounce off of?

 

Oh, yeah, a bunch that's what's disturbing. It's just strange.

It was around noon and the road was full of trucks. I was doing around 75 before I slowed down; the statute requires at least 6 over before a citation when using radar and I've never seen a citation for less than 15 over

 

Weird. It sounds like its a popular spot for them. Use that for your advantage, drive by a couple more times and see if you get anything. Do you know anyone else with a different unit? It'd be great to go by with a different unit and see if you get anything. Does your unit go off other times, like by banks etc? Wondering if it's your sensor. Time for a bit of controlled trial and error before you depend on it.

 

8500ci isn't good enough in my opinion. Bel STIR+ is the way to go. Much more sensitive.

 

Radar signal strength varies wildly. In Texas my 9500i picks up radar typically outside visual range. When I lived in Vegas and when driving across Lake Mead National Park (heavy radar presence) my detector gave me maybe a 200' warning at times. There are a lot of variables in this equation.

 

Clocking speed with radar at 45 degrees to traffic flow is odd. Since the speed reading drops off with the cosine angle, at 45 degrees the speed he clocks you at is only 67% of your true speed. Of course, if he understands the relationship between measured speed and angle to traffic he can set his speed limit trigger accordingly, in this case at 67% of the speed limit.

 

Yeah. That's what i thought. It's bizarre. He was just standing there next to his cruiser with no chase car about a 1/2 mile from the off ramp. They usually sit in their cars (there is moving radar in PA) like spiders waiting a meal.

 

I got hit in the same place last summer doing 95 in my Merc E55. Cop was cool and just gave me a ticket for not obeying a traffic sign and not speed.

 

That explains it. He's after radar detector equipped cars.

Section 3111 is Obedience to traffic-control devices.
It's a non-point offense.
You pay the fine and you move on...that's it. no points.,


Speeding is a point offense.

I think that that the Trooper found a way to catch radar detector equipped cars. By using his speed gun to determine if someone is moving at excessive speed...the 45 degree angle of the radar gun probably can't tell him precisely how fast but can indicate if it's real fast. That 45 decree angle probably scatters radar emission reflections so that they are not easily picked up.

While he may not have sufficient evidence to prove speeding, he can probably testify that it was excessive and the 3111 requires less proof.

In my experience Troopers rarely give a 3111 on the street. They usually allow a guilty plea to that section before trial after writing up a ticked for speeding.



Section 3111 provides:

§ 3111. Obedience to traffic-control devices.
(a) General rule.--Unless otherwise directed by a uniformed police officer or any appropriately attired person authorized to direct, control or regulate traffic, the driver of any vehicle shall obey the instructions of any applicable official traffic-control device placed or held in accordance with the provisions of this title, subject to the privileges granted the driver of an emergency vehicle in this title.
(a.1) Penalty.--
(1) A person who violates this section commits a summary offense and shall, upon conviction, pay a fine of $150. No costs or surcharges imposed under 42 Pa.C.S. § 1725.1 (relating to costs) or section 6506 (relating to surcharge) shall be assessed or imposed upon a conviction under this section.
(2) Notwithstanding any other provision of law, including 42 Pa.C.S. § 3733(a) (relating to deposits into account), the fine collected under paragraph (1) shall be deposited as follows:
(i) Twenty-five dollars of the fine shall be deposited as provided under 42 Pa.C.S. § 3733(a).
(ii) After deposit of the amount under subparagraph (i), the remaining portion of the fine shall be deposited into the Public Transportation Trust Fund.



Clearly, he's not looking to make an excess speed pinch.

 

I think it would be hard convincing some judges that you could measure the angle precisely at the time of clocking.

ChuckJ

 

It wouldn't surprise me in the least if their is equipment capable of calculating the forward speed even at an incident angle. it is effectively what any air traffic radar or airborne surveillance radar does when measuring ground or relative speed of other aircraft..

Effectively it can tell from successive samples and once it has a target return it can easily determine the relative motion with respect to the radar gun/source. Then once it determines the relative motion than it applies the math to the figure out the scalar speed.. What gets complicated is when there are multiple target in close proximity.

Do the LE guns actually do that? No clue, but they certainly could... otherwise yes, the only angle that would provide a correct speed would be at a head on.. front or back..

But I assume the capabilities of specific equipment and use limitations are part of the overall certification that goes on for the certification of LE equipment within the jurisdiction...

All of that said, a little googling on LE equipment seems to indicate that there is little direction capability present in the equipment currently available. What keeps coming up is that "trig" is necessary for effective use.. So who knows maybe the cops are now trained in a little math..

 

This is a problem with the software design of the 9500i. It filters the signal for falsest and often incorrectly filters real signals. This results in a non-linear ramp up of the signal strength to the user. I used to have a 9500i and sold it for this reason. On the radar forums this design issue is widely discussed.

The Bel STIR+ is programmed to deliver a more linear ramp-up.