Signs for Idiots

[signalman]

I just thought of a sign that I know I've seen on interstates in congested areas before:
WATCH FOR STOPPED TRAFFIC
No shit, thanks!  That's good advice regardless of what road one is driving on.

You don't normally see stopped traffic on an interstate.  This sign is merely alerting you to the good possibility that it will happen here.  Seems reasonable to me.

True enough, but my point was that a driver should be alert enough to see traffic slowing or stopped ahead and react accordingly.  I don't feel that one needs to be warned of such a thing. 

[agentsteel53]

sometimes geography prevents one from seeing backed up traffic.  a section of I-5 southbound at I-710 in Los Angeles is like this.  I know from experience that if I'm doing 80mph, I am fine, but if I am doing 60mph, I must slow down to 30 for seemingly no reason.

[Alps]

Oh, and does PennDOT still have any of those "keep two dots following distance" setups left anywhere? I remember them from several years ago, but I can't recall seeing any recently.

Yes.  I 80 WB before the East Stroudsburg exit.

No, removed due to Jersey driving. There's no way anyone's staying one dot apart (and didn't it start out as two? I seem to recall).

[signalman]

Oh, and does PennDOT still have any of those "keep two dots following distance" setups left anywhere? I remember them from several years ago, but I can't recall seeing any recently.

Yes.  I 80 WB before the East Stroudsburg exit.

No, removed due to Jersey driving. There's no way anyone's staying one dot apart (and didn't it start out as two? I seem to recall).

They were removed?  I didn't realize.  I haven't been out to PA via I-80 in quite a while

[kphoger]

Am I the only one on here who doesn't know what 'two dots following distance' means?  I learned the rule of two seconds for every ten feet of vehicle length, but none of that phrase is related to a dot.

[1995hoo]

Am I the only one on here who doesn't know what 'two dots following distance' means?  I learned the rule of two seconds for every ten feet of vehicle length, but none of that phrase is related to a dot.

I may be misunderstanding, but I was picturing either literal dots painted on the road and you should see two of them between yourself and the car in front of you, or else "dots" referring to the dotted line on the road such that you should keep two of those between you as well. I think what I'm picturing is something similar to the chevrons on the M4 near the M32 (see photo below; the speed limit there is 70 mph, BTW).

I recall also being taught to maintain a number of seconds between my car and the vehicle ahead, but vehicle length never factored into it. I think the rule of thumb was two seconds for speeds up to 40 mph and four seconds above 40 mph. Problem is, in real life that's utterly impossible. Four seconds' following distance leaves such a large gap that it is impossible to maintain it because somebody else will move into that space; if you then back off to restore four seconds, the same thing happens again.

[kphoger]

Most of us don't learn that the two-second rule is for every ten feet of vehicle, because we learn how to drive in passenger cars.  I only learned that in a driving safety class for driving a commercial vehicle.  Imagine how long it takes a semi truck with three trailers to come to a stop, compared to a school bus, compared to a Ford Ranger.

[1995hoo]

Good point. I do recall when I drove a rental truck from Brooklyn to Northern Virginia about 11 years ago being very cognizant of the stopping distance and the limited visibility. Tell you what, it gave me a much greater respect for, and understanding of, truck drivers because it was a chance to observe first-hand from a different perspective just how little understanding most car drivers have of the limitations on truck drivers (visibility and blind spots being the biggest one).

[BamaZeus]

We were always taught 2 seconds behind the next vehicle, without any regard to distance.  I myself have noticed that a good guide for me is being able to read a license plate at highway speed.  If I can fully make out a license plate of the vehicle in front of me, I'm probably too close, even with my exceptional distance vision.

But again, that's just for my pair of eyes, and this doesn't work in the city.

[PHLBOS]

I may be misunderstanding, but I was picturing either literal dots painted on the road and you should see two of them between yourself and the car in front of you, or else "dots" referring to the dotted line on the road such that you should keep two of those between you as well. I think what I'm picturing is something similar to the chevrons on the M4 near the M32 (see photo below; the speed limit there is 70 mph, BTW).

In PA, the "dots" are basically white solid circles maybe about 2 feet diameter.  It does the similar job as your posted-chevrons.

Although the below-image is from MN; PA has similar.

[agentsteel53]

the public campaigns would probably be a lot more effective in improving traffic flow and reducing accidents if they were reversed in their orientation.

"guy behind you is fewer than two dots away?  move your hind over to the right!"

[Alex]

Am I the only one on here who doesn't know what 'two dots following distance' means?  I learned the rule of two seconds for every ten feet of vehicle length, but none of that phrase is related to a dot.

Photos I took of the setup along US 322 east of State College last month:

[1995hoo]

Thanks for the pictures. Never seen that before in the USA. That first sign Alex posted looks like it's probably fairly new, as it appears to be a Clearview sign.

I'm curious, do those roads that have this "dot" system have passing zones? The reason I ask is because obviously when you want to pull out and pass on that sort of road, you want to follow a lot closer than "two dots" away in order to execute the pass as quickly as possible.

[J N Winkler]

I recall also being taught to maintain a number of seconds between my car and the vehicle ahead, but vehicle length never factored into it. I think the rule of thumb was two seconds for speeds up to 40 mph and four seconds above 40 mph.

That was a staple of driver education in the late 1980's/early 1990's.

Problem is, in real life that's utterly impossible. Four seconds' following distance leaves such a large gap that it is impossible to maintain it because somebody else will move into that space; if you then back off to restore four seconds, the same thing happens again.

It's not impossible at all--that is how I routinely drive.  The secret is to choose a speed low enough (in my case, a few hairs below the posted limit) to make it easy to pay out additional empty distance when cars cut in front of you.  I usually find I can maintain at least a two-second following distance (and usually at least four seconds in rural areas) without too much trouble, unless traffic is really heavy or I am dealing with drivers who maneuver like jackrabbits (speed up to pass me, cut in front of me, and then tread on the brakes when they realize the traffic in front of them is going much slower than they are).

Good form is not to cut back into the driving lane after passing another vehicle unless you have given that vehicle at least a two-second following distance.  I see this courtesy observed so rarely on the freeways that I always think better of drivers who observe it; but even the ones who cut back in relatively early are usually going fast enough that the minimum two-second following distance is restored within a relatively short period of time, without my having to brake or disengage cruise control.

[1995hoo]

OK, I'll amend my statement: When you drive in the DC area and surrounds, it's impossible to maintain a four-second following distance.

[kphoger]

Good point. I do recall when I drove a rental truck from Brooklyn to Northern Virginia about 11 years ago being very cognizant of the stopping distance and the limited visibility. Tell you what, it gave me a much greater respect for, and understanding of, truck drivers because it was a chance to observe first-hand from a different perspective just how little understanding most car drivers have of the limitations on truck drivers (visibility and blind spots being the biggest one).

It's had the opposite effect on me:  I now take a dimmer view of truckers who tailgate, especially when they're pulling two trailers.  Before, I never much thought about the added stopping distance.  OTOH, I don't grumble nearly so much about passenger cars that tailgate truckers:  the truck will take longer to stop than the car.....assuming the truck's brake lights work.  On our most recent trip to México, we were in heavy I-35 traffic approaching Waco from the north.  Traffic was only moving at about 45 mph or so, with frequent slowing and accelerating.  I found out, after slamming on my brakes a few times, that the delivery truck in front of me had no working brake lights.

[hm insulators]

I just thought of a sign that I know I've seen on interstates in congested areas before:
WATCH FOR STOPPED TRAFFIC
No shit, thanks!  That's good advice regardless of what road one is driving on.

You don't normally see stopped traffic on an interstate.  This sign is merely alerting you to the good possibility that it will happen here.  Seems reasonable to me.

Especially if there is a blind curve or hilltop. Such signs might actually be useful for out-of-towners unfamiliar with the route.

[1995hoo]

Good point. I do recall when I drove a rental truck from Brooklyn to Northern Virginia about 11 years ago being very cognizant of the stopping distance and the limited visibility. Tell you what, it gave me a much greater respect for, and understanding of, truck drivers because it was a chance to observe first-hand from a different perspective just how little understanding most car drivers have of the limitations on truck drivers (visibility and blind spots being the biggest one).

It's had the opposite effect on me:  I now take a dimmer view of truckers who tailgate, especially when they're pulling two trailers.  Before, I never much thought about the added stopping distance.  OTOH, I don't grumble nearly so much about passenger cars that tailgate truckers:  the truck will take longer to stop than the car.....assuming the truck's brake lights work.  On our most recent trip to México, we were in heavy I-35 traffic approaching Waco from the north.  Traffic was only moving at about 45 mph or so, with frequent slowing and accelerating.  I found out, after slamming on my brakes a few times, that the delivery truck in front of me had no working brake lights.

Understand that too, but I see a lot more bad behavior, or just plain stupid behavior, by car drivers around trucks. I think the place where I see the most of it is probably I-81 in Virginia. The portions I typically use run along the foothills of the mountains and it's two lanes per side with heavy truck traffic. People trying to get around the trucks just do a lot of flat-out stupid things, like cutting in front of them on a downhill grade without leaving space. Driving the rental truck gave me a much greater appreciation for why things like that are so foolish.

Not disputing that there are lousy truck drivers out there too, but my experience is that if you demonstrate that you have some level of understanding of their vehicles' limitations/needs and of the signals truck drivers use to each other, many (certainly not all) truck drivers can be cooperative, since they know your car is faster and more maneuverable than their rigs. In terms of signals I'm thinking of things like flicking your lights off to indicate when it's clear to move over.

[deathtopumpkins]

I was taught to keep either 1 second for every 10 mph or 1 carlength for every 10 mph apart when I learned to drive in VA. Every single state I've driven in I've observed this to be impossible. Someone ALWAYS moves over in front of you.

[PurdueBill]

Photos I took of the setup along US 322 east of State College last month:

I'll say it....Clearview on that sign is a deal-breaker.  I'd obey the Minnesota one but ignore the PA one.

I was taught to keep either 1 second for every 10 mph or 1 carlength for every 10 mph apart when I learned to drive in VA. Every single state I've driven in I've observed this to be impossible. Someone ALWAYS moves over in front of you.

Indeed, it is nearly impossible to allow the safe distance whenever there is much of any traffic.  Heck, I've seen it many, many times on US 30 in western Ohio ( I'm not sure what it is about that road but I notice it happens a lot there) that I'll be rolling along with the cruise on 71 mph, with little other traffic, and someone appears out of nowhere behind me (entered from another road? Came along doing 90 mph?), passes me, and (usually without signaling) pulls into the right lane in front of me with very little room to spare--then winds up going no faster than I was in the first place such that there would be half a second separation between their trunk and my hood if we are lucky.  Why not pass with more clearance?  Why not pull into the right lane further ahead?  Idiots.....

[NE2]

2 seconds following distance gives you 2 seconds reaction time, assuming both sets of brakes are equivalent. Speed and vehicle length have nothing to do with it (except insofar as the latter affects braking). So if your brakes suck compared to the vehicle in front of you, you may have to use a more complicated formula. But in a typical car, 2 seconds is a good rule, as long as you're paying attention.

[agentsteel53]

Why not pass with more clearance?  Why not pull into the right lane further ahead?  Idiots.....

why slow down?  drivers that can't be bothered to maintain a constant speed are a real nuisance.

[PurdueBill]

Why not pass with more clearance?  Why not pull into the right lane further ahead?  Idiots.....

why slow down?  drivers that can't be bothered to maintain a constant speed are a real nuisance.

That's what really gets me about those people.  I have the cruise on 71 mph and leave it there, they come tearing past me, dive in front of me, and slow down, sometimes to less than 71 mph even, so I have to slow down and sometimes wind up passing them!  What they hell are they thinking?  They have to be out trying to mess with people or trying to start a road rage incident.  I'd rather they just stay in the left lane for miles themselves than dive into the right lane in front of me and slow down.  I just don't get it.....

[Alps]

Thanks for the pictures. Never seen that before in the USA. That first sign Alex posted looks like it's probably fairly new, as it appears to be a Clearview sign.

I'm curious, do those roads that have this "dot" system have passing zones? The reason I ask is because obviously when you want to pull out and pass on that sort of road, you want to follow a lot closer than "two dots" away in order to execute the pass as quickly as possible.

Pennsylvania does not use passing zones. They use an innovative system called "centerline rumble strips." I have coined the term "Pennsylvania passing zone" to refer to a long straightaway with no marked passing zone, but sufficient sight distance that you can pass.

As for following distance - I also learned "2 seconds". As has been said, 2 seconds accounts for reaction time (which is the same at any speed), and correspondingly longer distance as speed increases. I've also heard "1 car length per 10 mph" but found myself to be a very poor judge of car lengths. I had someone once chastise me when I told them I use the 2 second rule, saying you "have to" use the 1 car length rule - frankly, that's idiotic. I'm going to use whatever rule keeps me safe. (Given that I drive in the northeast, I use a 1 second rule. 2 seconds is ideal in areas where people don't cut into spaces, like the West.)

[J N Winkler]

That's what really gets me about those people.  I have the cruise on 71 mph and leave it there, they come tearing past me, dive in front of me, and slow down, sometimes to less than 71 mph even, so I have to slow down and sometimes wind up passing them!  What they hell are they thinking?  They have to be out trying to mess with people or trying to start a road rage incident.  I'd rather they just stay in the left lane for miles themselves than dive into the right lane in front of me and slow down.  I just don't get it.....

I don't think it is necessarily always the case that a person who maneuvers in this fashion is trying to create frustration.  He might, for example, have started his overtaking maneuver at the tail of a long platoon, felt compelled to speed up in the left lane in order to avoid unduly delaying faster vehicles on his tail, and then wanted to return to the right lane as fast as possible in order not to encourage them to slalom around him.  (It is the combination of cutting in and slowing down that aggravates--but I think it is unavoidable to an extent because people vary considerably in their ability to judge speed differentials before they initiate overtaking maneuvers.)