Homemade Speed Trap Made By Former UVA CS Professor (cvilletomorrow.org) 582
An anonymous reader writes: Irritated by speeders in his neighborhood and frustrated with the City of Charlottesville's inability or unwillingness to enforce the speed limit, a former professor in the Computer Science department of the University of Virginia created a program in openCV to track vehicle speed on his residential neighborhood street: "You'll find that almost 85 percent of the cars going by are violators [of the neighborhood's 25mph limit]". This includes a city bus doing 34mph.
How to improve Slashdot (Score:5, Insightful)
Add a link to the summary.
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http://www.cvilletomorrow.org/... [cvilletomorrow.org]
http://myinforms.com/en-gb/a/2... [myinforms.com]
http://www.dailyprogress.com/n... [dailyprogress.com]
(Maybe he read from one of the above)
Re: This is a site for the technically competent? (Score:2)
I'm on mobile, and there is no link I can see next to the headline. This is the first article I've seen like this in...ever?
Escaped review? (Score:2)
How did this submission get through review? There's no link to the source article.
Slashdot's accepting citations from anonymous sources with no supporting evidence now?
Speed limit reality check (Score:4, Informative)
Authorities all over the world know that people will always go a little bit over the speed limit and hence set the limits accordingly. I know this isn't what the road safety warriors want to hear but its the truth - if they want vehicles doing around 35 authorities will set the actual limit to 30 and so on.
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Except in West Virginia. If you are not doing the speed limit or below, it is your own neck you are risking.
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they do everything but just goddamned move
Move? Where to? How do you commute to work if there's no streets?
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No no, children shouldn't be afraid of cars. There should be nothing bad if a kid streaks out into the street. Everyone should be traveling 20 in a 25mph because... what about the children?
WON'T ANYONE THINK OF THE CHILDREN??
Grace? (Score:5, Informative)
There is also an unwritten "grace" that is given in many areas, where you don't ticket someone until they go 10 mph above the speed limit. To get a ticket for going 34 mph in a 25 mph zone usually means you angered a cop, you were doing it in bad weather or at some other time when it was unsafe, or you wandered into a local town's legal extortion racket--excuse me, speed trap.
It is constitutionally questionable because of vagueness and due process, but it's still how driving works in a good part of the United States.
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There is also an unwritten "grace" that is given in many areas, where you don't ticket someone until they go 10 mph above the speed limit. To get a ticket for going 34 mph in a 25 mph zone usually means you angered a cop,
Yeah, that's just for selective enforcement, so they can punish brown people for being.
Missing link (Score:2)
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therefore the speed limit is invalid (Score:5, Interesting)
At least in California, other than the absolute maximum, and things like school zones, roads have to be surveyed periodically, and the speed limits must reflect the prevailing speed. If it is 85% near some higher number, including mass transit, then the limit is too low.
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Easy solution. Just put a speed camera on the side of the road, bright and visible. Then survey the area the speed camera is pointed at.
Still "too low"? By who's judgement? Mass swarms of human have absolutely no judgement or ability to perform risk analysis at all so they are probably the single worst source of information as to how a speed should be set. The only exception to this rule is large well built highways. Humans are good at judging risk when there's nothing unexpected that can come from a side s
Re:therefore the speed limit is invalid (Score:4, Insightful)
If that 85% are not crashing into things seems rather safe to say they are correct. Would be hard to find any road where nearly 1 in 6 cars has an accident each time they drive through.
More info? (Score:4, Interesting)
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Here is a Raspberry Pi version FYI (Score:4, Interesting)
I like the small-town Mexican solution (Score:5, Funny)
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"85%" (Score:5, Informative)
"You'll find that almost 85 percent of the cars going by are violators"
Then your speed limit is set too low, unless there is some compelling reason for it to be that low speed limits should be set by the average traffic speed (within reason). I think my state even has a law to that effect.
Seems like a physics problem to me (Score:2)
Maximum line of sight. Inclination, curve, drainage, presence of sidewalk, distance to intersection, distance to driveway, populaton of children, proximity to school, width, apparent width.
Then setup a traffic cone at various detail points in the road and measure the distance to the cone to make cars stop. You just need a cone, adjustable speed limit indicator, and a tape measure.
Lithopolis, OH; RIP (Score:2)
On my way to Canal Winchester on OH-674, I’d pass through a small section of Lithopolis, where the speed limit inexplicably drops to 45mph. It’s a well-known speed trap, for the locals, so the village makes(or made) money mostly from visitors. One time, an Ohio state legislator was caught in that speed trap, and there was a bit of a smack-down that ensued. But that wasn’t the beginning of the end of Lithopolis. That started when they closed the only interesting thing in the whole villa
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His next project (Score:2)
One By One (Score:3)
Re:legalism is a crap philosophy. (Score:4, Insightful)
If everybody is speeding, maybe the speed limit is too low.
Probably not, as The Fine Article states near the top: "... installed a camera on his roof and began writing speed-monitoring software after a 12-year-old pedestrian was injured by a car last October."
Comment removed (Score:5, Informative)
Re:legalism is a crap philosophy. (Score:4, Insightful)
Two things about this, one, slower vehicles are much easier to avoid for careless kids and two, speed kills, every extra ten miles an hour exponentially increases the likelihood of the pedestrian being killed when hit.
Re:legalism is a crap philosophy. (Score:5, Insightful)
So set speed limits at 10mph, or 5mph, or ban cars entirely if decreasing fatalities is always a justification for decreasing a speed limit, because if it isn't then you need a more credible case.
In the UK the normal speed limit in a residential area is 30mph. 20mph limits in the vicinity of schools are becoming more common. In general UK speed limits are quite relaxed, and especially on non-urban roads policing of moderate speeding is very limited; It is not at all unusual to find traffic averaging 80+mph on UK motorways (interstates) which have a 70mph limit, and you could comfortably do 90mph if traffic is flowing with no real risk of a ticket.
All of this should make the UK a very dangerous place for pedestrians if speed limits alone were a primary driver of road fatalities, but they aren't. The UK averages 3.6 fatalities per billion kilometres driven. The US average (where limits are on average lower) is 7.1, which is effectively double. It seems much more likely that issues like car quality, driver certification, road design, car design etc are far more influential.
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All of this should make the UK a very dangerous place for pedestrians if speed limits alone were a primary driver of road fatalities, but they aren't. The UK averages 3.6 fatalities per billion kilometres driven. The US average (where limits are on average lower) is 7.1, which is effectively double. It seems much more likely that issues like car quality, driver certification, road design, car design etc are far more influential.
I would say that the UK is much more pedestrian friendly than the US in general. Just one example is the use of zebra crossings. Also the level of driver education is higher in the UK, in my experience.
Re:legalism is a crap philosophy. (Score:5, Informative)
I don't disagree with your point, but you're conflating a bunch of numbers which aren't really comparable.
1) Motor vehicle fatality rate doesn't tell you much about pedestrian fatality rate.
2) Driving distances area greater n the U.S. so those billion kilometers driven are not comparable. Dividing the fatalities per 100,000 inhabitants by fatalities per billion km [wikipedia.org] yields 8100 km/inhabitant per year in the UK, versus 14,900 km/inhabitant per year in the U.S. So the average American travels 84% further each year than the average UK citizen. Most likely, a greater percentage of those U.S. miles are at higher speeds on highways where accidents are more likely to be fatal.
The problem at speeds higher than about 50 mph is physics. Given how bodies strapped inside a car react in a crash, 50 mph is about the point where internal organs and blood vessels start tearing apart from their own momentum in a crash. At 100 mph, accidents are almost always fatal for the same reason (energy that goes into tearing up your internal organs is 4x more than at 50 mph). So a disproportionate number of traffic fatalities come from these higher speed accidents. In other words, a single stat like fatalities per billion passenger km doesn't give you the complete picture. You need to control for traffic speed distribution within those billion km first just determine if there's any blame left over to be assigned to other factors like car quality, driver certification, road design, car design, etc.
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Two things about this, one, slower vehicles are much easier to avoid for careless kids and two, speed kills, every extra ten miles an hour exponentially increases the likelihood of the pedestrian being killed when hit.
Speed limits should be set based on the first only. The entire objective is reduce the probability of and accident to an acceptable level, not reduce it's severity.
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Speed limits should be set based on the first only. The entire objective is reduce the probability of and accident to an acceptable level, not reduce it's severity.
Yeah - my seatbelts, crumple zone, side impact airbags, front impact airbags, passenger airbags, re-enforced pillars, side impact beams, automatic roll shut off, bumpers, safety glass, etc. all are very helpful at reducing the probability of an accident. That's a seriously wrong statement.
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Speed limits should be set based on the first only. The entire objective is reduce the probability of and accident to an acceptable level, not reduce it's severity.
Yeah - my seatbelts, crumple zone, side impact airbags, front impact airbags, passenger airbags, re-enforced pillars, side impact beams, automatic roll shut off, bumpers, safety glass, etc. all are very helpful at reducing the probability of an accident. That's a seriously wrong statement.
None of those items has anything to do with how speed limits are set.
Dear black and whiter (Score:4, Informative)
The context was *a residential street*. Stop generalizing something which was very obviously not meant to be general, that's just intellectually dishonest. Alternatively you're suggesting that you're too stupid to realize that.
Re:Dear black and whiter (Score:5, Insightful)
You're not considering that the 4 lane avenue is wider and probably busier, and thus scarier to kids. A sleepy residential street on the other hand is the kind that a kid might cross without really thinking about because 9 times out of 10 (or more) a car isn't coming.
Therefore you can't assume the streets have to be treated the same just because of proximity.
Re:Dear black and whiter (Score:4, Insightful)
The fact that it's a four lane avenue rather than a residential street. Kids aren't generally stupid, just inexperienced about entitled assholes who think they're above the law.
No, we don't "have to". We also have the option of simply enforcing existing speed limits with a special emphasis on residential streets and other low-limit areas. Just make the fine proportional to ((speed - limit) / limit) and unwillingness to enforce shouldn't be an issue anymore.
Re:Dear black and whiter (Score:4, Interesting)
I grew up less than 100M from a busy 4 lane street, where traffic often moves at 40MPH. The street where I grew up, was "sleepy" except for the idiots who thought that 40MPH traffic was too slow, and went 50 MPH down my street (25MPH residential) to get around the "slow" mainstreet. And now, with apps like WAZE telling people how to bypass the busy streets for the less busy streets, the road I grew up on, is no longer safe for kids, at anytime.
What I don't get, is why people feel the need to justify Speeding down Residential streets where kids want to play, simply because they are inconvenienced by normal traffic.
Following your logic, we would need a $50,000/6 Month traffic study to justify wanting 25 MPH residential street speeds for every neighborhood that wanted them. Here's a fucking thought, how about you drive 25MPH in a residential neighborhood, and if you can't, then don't drive those streets.
People complaining about residential neighborhoods aren't the ones that usually live there.
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So, you're the selfish twit that drives 50 MPH on a residential street, expecting kids to dodge your car. Got it.
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Which has f' all to do with the fact that a car travelling at 20mph is not likely to kill someone it hits and a car travelling at 30mph is massively more likely to kill anyone it hits.
I see nothing in your calculation about the probability of brain damage or death from high speed collisions.
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the term "exponentially" is being abused.
No. Unless you're talking about x^1, exponentially is not being abused. What else are you going to call it? Linear? What's your threshold for exponential? x^3?
So it's true...all the nerds really have abandoned Slashdot. We now have a place where the parent comment, which a high-school algebra student should recognize as foolish, gets modded "Insightful". I think I've finally had enough of this place.
So where do the cool kids hang out now? Oh my god, look who I'm asking!
For the record: x^2 is quadratic, x^3 cubic, x^4 quartic, etc., c^x is expontential
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Exponential function is not the same as an exponential relationship. You're using the term "exponential function" as equivalent to exponential.
Re:legalism is a crap philosophy. (Score:5, Insightful)
Re: legalism is a crap philosophy. (Score:3)
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Re: legalism is a crap philosophy. (Score:2)
I suspect they hinder emergency vehicles enough to cause more deaths than loves saved.
Speed bumps do this already, and this tech seems it would do so more.
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Curves and obstacles do not slow people down. Instead, people have more problems staying in their own lane.
Police are not enforcing laws because they are being assaulted by the media and obnoxious part of the public. Why do your job when you're going to get prosecuted? Doubling of murders and other crimes hasn't turned things around - it'll take something big like Baltimore completely burning down before people wake up and reject anarchy.
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They're far from ubiquitous and older neighborhoods are often grids without speed bumps. European cities are much older in general, so I would think there would be a mix too.
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Japan started painting fake little pyramid shaped obstacles in the road. Being flat paint they don't annoy you like speed bumps, but they are quite effective at slowing down traffic. Some other east Asian and European countries have started adopting them (IIRC Denmark was one of them).
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What happens in Europe is that they start making the streets in such a way that they are automatically so that you drive a lower speed. Especially in neighbourhoods where people live.
I live there. What happens in practice, is that the people that were already obeying the speed limit are slowed down. And the people that were speeding before, see it as an obstacle course challenge, going as fast or faster as before, but now also swerving dangerously... Also, when you put a big obstacle on the road, people tend to focus on that, instead of watching out for pedestrians.
Where I live, there's a sudden road divider and recombiner intended to slow drivers down from a 40mph zone to a 25mph zone. But every part of the street is well lit with overhead lamps except this road obstacle. There are always dark tire marks on the curbs there.
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If everybody is speeding, maybe the speed limit is too low.
Probably not, as The Fine Article states near the top: "... installed a camera on his roof and began writing speed-monitoring software after a 12-year-old pedestrian was injured by a car last October."
How fast was that person going? Was it a drunk driver? Was it a half-blind OAP? None of those details regarding the aforementioned accident are in the article, only the fact that some people drive down this guy's street at the breakneck speed of 34mph.
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That is the go to fix for traffic safety. Lower the speed limit.
There was an accident where I live a few years back and they figured the speed limit was too high.
Not really thinking. It was an area of 3 intersection that had 6 lanes of traffic all going in different directions where to get to your destination you need to be in the correct lane. On a steep hill Then to top it off people j-walk across this all the time while there is a good cross walk 100 meters pass this tricky traffic intersection. The thi
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If everybody is speeding, maybe the speed limit is too low.
Probably not, as The Fine Article states near the top: "... installed a camera on his roof and began writing speed-monitoring software after a 12-year-old pedestrian was injured by a car last October."
Single data point. Anecdote.
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Or, alternatively, the punishment for speeding isn't harsh enough.
It all depends on your point of view of whether a legal limit is a legal limit, or something you can just ignore without consequence.
If you were only allowed to bring 100 cigarettes back from abroad and you took 110, and it was plainly stated everywhere, and it was common knowledge, and you had to pass a cigarette test to be allowed abroad, and there were signs all over the place, would you expect to get away with bringing back 110 cigarettes
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No, it's stupid but entirely predictable. There is a large demographic who think speed limits are fine or even too small. There's a large demographic who want to see them decreased. The status quo is political because you can't increase the limit due to one group and can't enforc
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Well if you're someone who believes that life begins at conception, then you're 21 years old when it's 20 years and 3 months after your birthdate.
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If everbody is speeding then the road layout is encouraging them to speed, redesign the road so 30 seems fast and people will drive slower
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Because, of course, the great majority of people carefully analyze the potential hazards that might appear on a road, such as cars backing out of driveways, and slow down to a speed that allows time to avoid collisions.
That's why, for instance, nobody ever runs into boulders on the road when driving around curves on mountain roads -- they know that turn very well and regardless of the silly regulatory 40 mph sign they know it's perfectly safe at 65.
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25 MPH (or 40 km/h) on a road of the quality seen in the video will usually feel like it is too slow, and it is not surprising that there are many that exceed this limit.
I notice that most arterial roads around here have the equivalent of 30 MPH (50 km/h) though reduced to 40 km/h or 25 MPH past schools. Where there also is at least one speed bump or raised pedestrian crossing (basically a speed bump with the crosswalk on top). Non-arterial roads have 30 km/h (which would correspond to 20 MPH), and there a
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This speed limit is reckless (Score:5, Informative)
Those who set that speed limit are acting in reckless disregard for the safety of the public. As is that CS professor--and he should know better!
Re:This speed limit is reckless (Score:5, Insightful)
It is very well established in the civil engineering literature how to set the speed limit for vehicle usersafety.
That 85% rule of thumb might work well for an Interstate highway, but it's a terrible metric for a local street, where the priority should be the safety of pedestrians.
Re:legalism is a crap philosophy. (Score:5, Informative)
The other main roads feeding into downtown from US 250 are High to the east and Park and McIntire to the west. All three are heavily congested for various reasons. They link to other busy roads, have shopping and commercial areas, etc
I think the solution is for the city to bite the bullet and install speed bumps. It will not be a popular measure, but that is because people want to speed through there to get into or out of the downtown area. Too bad, just plan a little further ahead.
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If everybody is speeding, maybe the speed limit is too low.
Or maybe human beings are horrible in risk analysis when driving in built up suburban areas where something can end up on the road way faster than reflexes allow when travelling at high speed?
Or maybe humans know what they are doing and are just dicks?
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If everybody is speeding, maybe the speed limit is too low.
Clearly the thought process for anyone who's driven through Atlanta, GA...
Re:legalism is a crap philosophy. (Score:5, Interesting)
Anyone that speeds in a residential area is the worst type of scumbag.
On an open highway, go for it, I think we should be allowed to go 100mph. Driving around people and kids only a few feet from their homes, they need a punch in the face to go along with the ticket.
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(Unless the law has changed...) California law says that if a high percentage (like 85%) of drivers go at or above a certain speed, then that speed is what the speed limit should be, regardless of the signage.
There was a case in Palo Alto about 25 years ago where the police set up a speed trap on Embarcadero between the 101 freeway and El Camino and one of the drivers caught in it paid to have the traffic monitored (without police presence which obviously influences drivers) and proved that he had been driv
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But the Think Of The Children campaigners will tell you that injuries to kids are X % less at 25 mph than 35 (or whatever). Which of course is a Reductio Ad Absurdum argument since you can then argue than 15mph causes less deaths than 25 etc and eventually get to the point where you end up with a 5mph limit and a man walking in front of the vehicle with a red flag and a whistle to warn people ahead. These people refuse to countenance the fact that there must be a trade off between road safety and society -
Re:25 mph? (Score:4, Informative)
There is no necessity for you to drive fast around residential areas, you want to go fast, hit a highway or a racetrack or quit whinging, FML.
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"There is no necessity for you to drive fast around residential areas,"
Define "fast"? I don't consider 35 fast, certainly not 25. And some suburbs go on for miles.
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"Fast" is a weasel word in this context used by the nanny staters.
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"Many roads in London are being limited to 20mph|"
Only by car hating left wing councils.
"a lot of the time the traffic wasn't going faster than that anyway."
Not in the day maybe. Try 2am instead then tell me 20mph is a sensible limit.
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Low speed limits steal time. Transportation is just the a means to get from a to b in the least amount of time possible. If pedestrians or bikes are a problem limit their access, roadways primary function it to allow cars to travel efficiently.
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My first house was at the far end of a large condo complex to the tune of 2 miles or so. The posted limit was 5. Now the main road was just that road to get feeder strs to the parking lots with a nice wide sidewalk where children road their bikes. 30ish minutes to drive what amounts to your driveway (shared condo property not a town road) is insane. The safe speed is easily determined as what a large percentage of the people normally drive at.
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"The safe speed is easily determined as what a large percentage of the people normally drive at."
I fail to see logic in this.
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Got people like you Mrlogic in our area. They campaigned for 25mph speed limits on my road and got it. Then I drive 25 and get a line of cars 2" from my bumper. After about 2 weeks of this, the speed limit went back up to 35.
I litterally had a woman that was waiting on the side of the road for her kid from school jump back and throw her arms up as I came around the corner at.... 37 in a 35. I would bet a large sum of money she'd be tailgating me in the same spot at 37 (I get a line of cars behind me whereve
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People like would be the first to whine if there was no ambulance crew to collect you after you'd fallen off your pedal bike because they got stuck in slow traffic getting to work.
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Oh wosdamatter diddums, can't think of a riposte so try for a deflection? Bless.
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Re:25 mph? (Score:5, Funny)
A 25 mph speed limit is unrealistic on any public road I've ever seen, with the exception of roads made of cobblestone. It's difficult to drive a modern vehicle that slowly--it takes concentration on your speed that frankly makes you have much less attention to pay to obstacles and hazards... like children.
Odd. My car drives at about that speed idling in third gear. It takes no effort at all. If I want a slower speed I pick a lower gear. It is a high volume production car with no mods.
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Utter crap. Does this mean you are not capable of driving your vehicle at 15mph or 10mph or 5mph? It must be excruciatingly difficult for you to drive at 5mph eh, god your brain must practically be hemorr
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Does this mean you are not capable of driving your vehicle at 15mph or 10mph or 5mph?
My last car had an engine idle speed around 7-8mph, meaning it was not possible to drive 5mph at all. Simply letting up on the break and not touching the gas at all would result in the car moving faster than 5.
It was also not possible to consistently drive 10mph, as the slightest touch of the gas pedal would cause the car to accelerate to just over that speed.
Mind you that doesn't mean I couldn't abide by a 10mph speed limit, it just means I can't do so while driving AT that limit, I have to not touch the
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Like I already said, I don't drive at the limit when it is that low...
Not sure why you felt the need to tell me to do what I literally just said I already do, but thanks for the accusation anyway.
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If you had said 5 mph, you would have an argument. It actually is difficult to make a car go 5 mph. A lot of them won't even read their speed accurately when going that slowly. Hell, mine doesn't even indicate any speed less than 10 mph!
25, on the other hand, should be no problem whatsoever, and if it is, you should give up driving immediately and go back to walking, because you can't drive for shit.
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It's difficult to drive a modern vehicle that slowly
In first gear without the foot on the accelerator, or with an automatic without your foot on the accelerator cars do about 5kph and are easily overtaken by mothers pushing prams.
If you find driving slow too difficult then maybe you shouldn't be operating heavy machinery. ... or be near anything hard.
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You are too stupid to be allowed to drive.
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He might be American and have no idea how to drive a stick shift.
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Um...no not crazy. Most people drive automatics...you put it in drive until you get to your destination. No gear changes required by the driver.
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Loops in the road would work, but that would require permission from the city to make the grooves and put down the wire into the top layer of pavement. The non-contact nature of this camera approach does not require anything to be done to or on the actual road.
postal codes (Score:2)
Several years ago, it was decided to standardize the abbreviations for the various states in the USofA. I presume that however it was decided, it was partly for readability. Way back when, an envelope might have "California", "Calif." (quite common), or "Cal", or whatever, making it difficult to quickly route mail.
VirginiA is VA, VermonT is VT, for example, but that pattern is not universal, as CAlifornia, ORegon, and WAshington are CA, OR, and WA, respectively.
If only the initial letter of the state is us
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So your polluting the commons by reporting false information.