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The Lowdown on Lidar

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Re: The Lowdown on Lidar

#71

Post by ylhert »

ihaveajob wrote: post #12

Speed radars are good for speed traps, but not so great to prevent speed related incidents. They share the same fatal flaw with all other single-point speed meters: You can just slow down for a minute, while you pass by the speed trap, and then speed up for the rest of your trip. Instead, a 2-point speed meter (i.e. license plate readers every few miles, measuring time between matching reads) system is superior becau…

In France they have a system that sort of works like this, most/many highways are toll based. There are toll booths at regular intervals(every 100 miles or so). If your time between toll booths is below a certain time, they know you were speeding at some point. To get around this, my always speeding grandpere would just have us stop for gas, un cafe, etc right before each toll booth.

Re: The Lowdown on Lidar

#72

Post by pyre »

MichaelDickens wrote: post #52
selectodude wrote: post #29

Earlier quoted context omitted.

It's not about saving lives. It's about revenue generation.

Speed limit laws don't exist to generate revenue. They exist to disincentivize speeding. If speed limit laws didn't exist, can you imagine lawmakers saying, "We need more money. Hey, I know! Let's charge people money for driving over a certain speed!"

The laws aren't put into place with the "let's generate revenue" mentality, but their enforcement is definitely done with respect to that mentality. If it's all about getting people to slow down, then:

1) Why aren't law enforcement more focused on getting people to slow down than writing tickets?

2) Why do traffic cops have monthly quotas for tickets?

3) In places where monthly quotas are against the law, why do 'performance revues' of traffic cops only focus on '# of tickets' as the largest performance metric? (basically a quota by another name)

4) Why is it so easy to bargain down a speeding ticket in a large city, whereas in a small town they are only willing to haggle on the points on your license (hint: because they still want you money)?

Re: The Lowdown on Lidar

#73

Post by ghkbrew »

timthorn wrote: post #57
malchow wrote: post #27

Earlier quoted context omitted.

"I can't believe [average speed camera systems are] not implanted at least in all interstate freeways." Possibly because a civil society, favoring the preservation of a measure of basic autonomy, does not implement every measure for tracking, enforcing, circumscribing, and monitoring the people.

In practice, they're actually very good for improving traffic flow on busy roads - because almost everyone is driving at the same speed, jams just don't form in the same way. The utilitarian argument for them is very strong.

Do you have evidence to back up that claim? It seems counterintuitive that slowing down the top few percent fastest drivers would improve traffic. If there's enough traffic to cause congestion wouldn't they be stuck behind slower drivers anyway?

Re: The Lowdown on Lidar

#74

Post by MattGrommes »

As a college intern at a national lab my boss' boss got a speeding ticket on the military base we worked on. He spent some time doing research and when he presented his evidence in court the judge apparently told him he wasn't going to have to pay the fine but the judge wasn't going to find him not guilty because he wasn't going to risk invalidating all speed gun findings. I don't recall if it was lidar but it's funny the stories are so similar. It's hard to use technology to mess with engineers. :)

Re: The Lowdown on Lidar

#75

Post by ylhert »

LIDAR sucks and there is no judicial notice on it in California. If you ever get a LIDAR ticket, do a trial by written declaration (or TBD). Just state that you dispute the validity and accuracy of the LIDAR reading and they'll usually throw it out. Remember to ask the officer(after he has given you your ticket) what model laser/radar detector he was using, and at what distance he measured you at. Anything over 800/1000 ft(this is really close, and rarely do they get you this close) will usually automatically be struck down if you question LIDAR's validity at that distance. That is a case you will win every time, if you do it right. The court cannot prove it's accuracy at these ranges and they know it. Also, rule of thumb, all CHP officers have laser only on their bikes now. source: I used to have a Lancer Evolution

Re: The Lowdown on Lidar

#77

Post by jpollock »

ihaveajob wrote: post #12

Speed radars are good for speed traps, but not so great to prevent speed related incidents. They share the same fatal flaw with all other single-point speed meters: You can just slow down for a minute, while you pass by the speed trap, and then speed up for the rest of your trip. Instead, a 2-point speed meter (i.e. license plate readers every few miles, measuring time between matching reads) system is superior becau…

This can be intentional. If there is a dangerous piece of road where the average speed of traffic is higher than the road will take, then put a trap in to slow the traffic down to the limit. It doesn't have to be over the entire highway system to have an effect on accidents.

For example, in NZ, there is a speed camera half-way down Ngauranga gorge in Wellington - a place where there is a blind turn down a steep slope and where the limit goes from 100kph down to 80kph.

http://en.wikipedia.org/wiki/Ngauranga_Gorge

Re: The Lowdown on Lidar

#78

Post by grndn »

reitanqild wrote: post #59
gonehome wrote: post #28

Earlier quoted context omitted.

OR it could be because speeding isn't that dangerous and the current limits on most roads don't represent what speed people actually drive at or what speed people could safely drive at. It's different on residential streets, but on freeways I think the way Germany handles it is better. Speeding tickets (and most traffic violations really) are not about safety or curbing behavior they're about generating revenue for t…

A Dutch engineer once told me (back before 2004 I guess ) that they once raised the speed limit on the roads in Netherlands only to find average speed decreased. His explanation IIRC was that 1. once people broke the limit it didnt matter how much and 2. when speed limits felt more correct more people respected them. I'd love to know if anyone has any pointers to research on this as around here speed limits are weird…

I used to live in Los Angeles. On the freeways, the speed limit was 55mph but I read once that the actual average speed was around 17mph.

My (unscientific) theory is that with higher speed limits, you get more traffic waves, and people try to change lanes more often, causing delays.

If the speed limit on LA freeways was only 25mph, I would hope that people would chill out and the traffic would flow more smoothly, resulting in a faster average speed than at present.

Re: The Lowdown on Lidar

#79

Post by evilduck »

MichaelDickens wrote: post #52
selectodude wrote: post #29

Earlier quoted context omitted.

It's not about saving lives. It's about revenue generation.

Speed limit laws don't exist to generate revenue. They exist to disincentivize speeding. If speed limit laws didn't exist, can you imagine lawmakers saying, "We need more money. Hey, I know! Let's charge people money for driving over a certain speed!"

Just like no community has ever been found to be shortening yellow light timers after setting up red light cameras, and no cops ever dubiously search cars for drugs so they can seize assets.

Just because they weren't conceived for a purpose doesn't mean that's not how they're used. Speed enforcement is very frequently performed by small town cops sitting on highways that are just barely in their jurisdiction. They're doing it for money, plain and simple.

See https://www.google.com/maps/preview?client=safari&q=hampton+... for proof of this.

Re: The Lowdown on Lidar

#80

Post by mnarayan01 »

Karunamon wrote: post #40
meritt wrote: post #14

Earlier quoted context omitted.

Because video cameras are arguably illegal. You can't face your accuser in court, therefore it should be thrown out. Got a speeding ticket from one of these lovely cameras in the state of Iowa, then I was sent a bill from some company in Phoenix with bold threats that if I didn't pay the fine, it'd be submitted to a collection agency and negatively impact my credit score (because otherwise I'd just have not paid it.…

This is a common myth. The camera is not your accuser; the state is, using the camera as evidence of your violation. It would be no different than a security camera catching you breaking into a building. The camera doesn't sue, the owner of the building does.

The "right to face your accuser" refers to witnesses. The state is _always_ the prosecutor in criminal cases (in the US, IANAL).
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