Take a look here on the link of a section of PA 309 near Wilkes Barre, PA that is considered a divided roadway on most maps, but if you look there is just a strip of concrete in the middle of the center yellow lines. I know many PA highways have this set up, and for the most part it was created for contrast purposes more than safety, obviously. The divider is not even a raised curb, but just enough for your eye to catch and for headlight reflection at night where as the rest of the pavement would not reflect (although there used to be concrete highways with this center strip at one time).
Would anyone say that this is a divider or just a simple undivided highway with a white strip in the middle of the center lines?
http://maps.google.com/maps?q=Plains,+PA&hl=en&ll=41.205845,-75.89628&spn=0.004205,0.010568&sll=37.0625,-95.677068&sspn=35.957999,86.572266&oq=plains,+&t=h&hnear=Plains,+Luzerne,+Pennsylvania&z=17&layer=c&cbll=41.20599,-75.896342&panoid=WqQtq0H9YYjYv0t9ReFzgw&cbp=12,194.17,,0,0
On a similar vein, would a continuous left turn lane on a rural highway be divided? Google map near Daleville, IN (http://maps.google.com/?ll=40.113518,-85.484936&spn=0.00192,0.004656&t=h&z=18). INDOT shows this as divided.
I would say technically the one in the middle of PA 309 is a divided highway because it is curbed. The IN 67 example however is not a divided highway because there is not break in the pavement.
For what purposes? Passing a school bus? Interstate standards? Drainage? Capacity? You'll get different answers depending on what you're doing with the road.
I would consider a highway to be divided if there is a lane or divider that is wide enough to store a left-turning vehicle, or if a narrower divider has a positive barrier such as a concrete or guardrail median barrier at least 30 inches high.
That segment of PA-309 has neither.
http://abetter54.com/54.html
Missouri considers this to be divided
The MUTCD defines a median as follows:
Quote from: MUTCDMedian–the area between two roadways of a divided highway measured from edge of traveled way to edge of traveled way. The median excludes turn lanes. The median width might be different between intersections, interchanges, and at opposite approaches of the same intersection.
Interestingly, "divided highway" is not defined in the introduction list of definitions. The inference I get is that a divided highway has some physical object dividing or separating two adjacent roadways or paths of travel. So a concrete splitter island or curb, no matter how narrow, would be a median that creates a divided highway. This seems consistent with how GoogleMaps interprets major streets.
So in the examples of above posts:
*PA 309 is a divided highway, due to the concrete splitter island (despite the insignificance of how little the concrete protrudes above the road surface.
*IN 67 is not a divided highway, as the only separation is a two-way left turn lane.
Quote from: roadfro on April 23, 2012, 03:47:25 AM
The MUTCD defines a median as follows:
Quote from: MUTCDMedian–the area between two roadways of a divided highway measured from edge of traveled way to edge of traveled way. The median excludes turn lanes. The median width might be different between intersections, interchanges, and at opposite approaches of the same intersection.
Interestingly, "divided highway" is not defined in the introduction list of definitions. The inference I get is that a divided highway has some physical object dividing or separating two adjacent roadways or paths of travel. So a concrete splitter island or curb, no matter how narrow, would be a median that creates a divided highway. This seems consistent with how GoogleMaps interprets major streets.
I'm not surprised that there is no formal definition in the MUTCD, as a median/divider (with the exception of a painted median) would be more of a geometric design feature, not necessarily a traffic control device (sign, signal, or marking). The AASHTO "Green Book" or Roadside Design Manual would be a better place to look for a formal definition. If I can remember to, I'll check them when I get back to the office tomorrow.
At least in our area design lingo, a divider would typically be a Jersey barrier, thin curb head, cable system or double-sided guard rail. A median would be anything significantly wider (4+ feet)--curbed or not.
Quote from: roadman65 on April 22, 2012, 06:52:23 PM
Take a look here on the link of a section of PA 309 near Wilkes Barre, PA that is considered a divided roadway on most maps, but if you look there is just a strip of concrete in the middle of the center yellow lines. I know many PA highways have this set up, and for the most part it was created for contrast purposes more than safety, obviously. The divider is not even a raised curb, but just enough for your eye to catch and for headlight reflection at night where as the rest of the pavement would not reflect (although there used to be concrete highways with this center strip at one time).
Would anyone say that this is a divider or just a simple undivided highway with a white strip in the middle of the center lines?
http://maps.google.com/maps?q=Plains,+PA&hl=en&ll=41.205845,-75.89628&spn=0.004205,0.010568&sll=37.0625,-95.677068&sspn=35.957999,86.572266&oq=plains,+&t=h&hnear=Plains,+Luzerne,+Pennsylvania&z=17&layer=c&cbll=41.20599,-75.896342&panoid=WqQtq0H9YYjYv0t9ReFzgw&cbp=12,194.17,,0,0
If it's mountable/traversable, I would say undivided highway. Not-mountable = divided highway.
From a practical standpoint, a highway is divided if there is a lane or divider that is wide enough to store a left-turning vehicle, or if a narrower divider has a positive barrier such as a concrete or guardrail median barrier.
Anything less than that, from a practical standpoint, is an undivided highway.
Quote from: Beltway on April 23, 2012, 08:59:54 PM
From a practical standpoint, a highway is divided if there is a lane or divider that is wide enough to store a left-turning vehicle, or if a narrower divider has a positive barrier such as a concrete or guardrail median barrier.
Anything less than that, from a practical standpoint, is an undivided highway.
I'd have to disagree with any definition of 'divided highway' that would count a two-way left turn lane as a "divider". A divider, from a truly practical standpoint, splits or *divides* traffic in such a way that does not allow traffic to easily cross from one roadway to the other...a TWLTL does not do that.
Quote from: roadfro on April 23, 2012, 09:50:56 PM
Quote from: Beltway on April 23, 2012, 08:59:54 PM
From a practical standpoint, a highway is divided if there is a lane or divider that is wide enough to store a left-turning vehicle, or if a narrower divider has a positive barrier such as a concrete or guardrail median barrier.
Anything less than that, from a practical standpoint, is an undivided highway.
I'd have to disagree with any definition of 'divided highway' that would count a two-way left turn lane as a "divider". A divider, from a truly practical standpoint, splits or *divides* traffic in such a way that does not allow traffic to easily cross from one roadway to the other...a TWLTL does not do that.
If that is the case, a 12-foot-wide grass median does not provide a divided highway, as it would allow traffic to easily cross from one roadway to the other.
I would disagree. It would be a narrow median, but a median nontheless. Same for a 12-foot-wide continuous turn lane.
On the other hand, a median usually (a) restricts where you can legally turn left and (b) provides a safe place for pedestrians to wait. A center turn lane does neither. As I said, there's no one-size-fits-all definition.
Quote from: NE2 on April 23, 2012, 11:54:43 PM
On the other hand, a median usually (a) restricts where you can legally turn left and (b) provides a safe place for pedestrians to wait. A center turn lane does neither. As I said, there's no one-size-fits-all definition.
On a rural highway those points are usually moot on the great majority of the length of the highway.
On an urban arterial the continuous turn lane can provide better access to properties, and traffic signals can obviate the need for a pedestrian to wait in the middle.
Which has what to do with whether it has a median or not?
Quote from: NE2 on April 24, 2012, 10:04:24 AM
Which has what to do with whether it has a median or not?
It has to do with whether the road is considered a divided highway. I wouldn't consider a road like that to be an undivided highway. Of course, YMMV...
On the other hand, a road with a 4-foot-wide separater that has a mountable curb, I would consider to be an undivided highway. Left turns would have to stop in the left lane until opposing traffic cleared.
So I guess this is all up to interpretation, so I'll just put in my two bits.
I would consider a divided highway to have EITHER of the following between directions of transit:
(a) A physical barrier such as curb lines or a Jersey barrier,
(b) Unpaved neutral space of any width,
(c) Paved neutral space of at least one full lane's width not intended for (and striped to discourage) vehicular traffic.
For the purpose of the law, however, (c) does not qualify as two roadways but as one.
Furthermore, what happens in the following case?
Say a highway is paved with about one meter of paved neutral space, just wide enough for a physical barrier. Down the middle runs a physical barrier, except for a five-mile-long segment where it's just two yellow lines separated by one meter of pavement. The distance between directions of transit doesn't change, the highway design characteristics are otherwise the same, it's just missing a barrier. Is it still a divided highway?
Quote from: kphoger on April 24, 2012, 02:12:59 PM
So I guess this is all up to interpretation, so I'll just put in my two bits.
I would consider a divided highway to have EITHER of the following between directions of transit:
(a) A physical barrier such as curb lines or a Jersey barrier,
(b) Unpaved neutral space of any width,
That would include the standard double yellow lines 12 inches apart, on an undivided highway.
Quote
(c) Paved neutral space of at least one full lane's width not intended for (and striped to discourage) vehicular traffic.
For the purpose of the law, however, (c) does not qualify as two roadways but as one.
Physically one, but functionally two.
Quote
Furthermore, what happens in the following case?
Say a highway is paved with about one meter of paved neutral space, just wide enough for a physical barrier. Down the middle runs a physical barrier, except for a five-mile-long segment where it's just two yellow lines separated by one meter of pavement. The distance between directions of transit doesn't change, the highway design characteristics are otherwise the same, it's just missing a barrier. Is it still a divided highway?
A positive median barrier makes it impossible to cross, so that would indeed be a divided highway, even if it is only 2 feet of median.
The Surekill Expressway is a divided highway. If the median barrier was removed, it would be an undivided highway, IMHO. Only 4 feet between the two roadways.
Quote from: Beltway on April 24, 2012, 04:26:51 PM
I would consider a divided highway to have EITHER of the following between directions of transit:
(a) A physical barrier such as curb lines or a Jersey barrier,
(b) Unpaved neutral space of any width,
That would include the standard double yellow lines 12 inches apart, on an undivided highway.
[/quote]
Only if those twelve inches of road are not paved between the yellow lines, which I've never seen.
Quote from: roadman65 on April 22, 2012, 06:52:23 PM
Take a look here on the link of a section of PA 309 near Wilkes Barre, PA that is considered a divided roadway on most maps, but if you look there is just a strip of concrete in the middle of the center yellow lines. I know many PA highways have this set up, and for the most part it was created for contrast purposes more than safety, obviously.
In my youth, I've been down many roads like this including this section of PA 309. What happened is that the concrete in the middle actually was a divider at one time and the layers of pavement have reduced it to what you see here.
Quote from: Beltway on April 24, 2012, 01:14:30 PM
On the other hand, a road with a 4-foot-wide separater that has a mountable curb, I would consider to be an undivided highway. Left turns would have to stop in the left lane until opposing traffic cleared.
You're saying a positive (although mountable) curb--thus a positive and physical barrier--would be considered an undivided highway? But a TWLTL--a simple non-positive division--makes a road a divided highway? This doesn't make any sense...
Quote from: Beltway on April 24, 2012, 04:26:51 PM
Quote from: kphoger on April 24, 2012, 02:12:59 PM
So I guess this is all up to interpretation, so I'll just put in my two bits.
I would consider a divided highway to have EITHER of the following between directions of transit:
(a) A physical barrier such as curb lines or a Jersey barrier,
(b) Unpaved neutral space of any width,
That would include the standard double yellow lines 12 inches apart, on an undivided highway.
I agree with the definitions (a) and (b). "Neutral space" would not be considered the space between double solid yellow lines, as that is operationally meant to be a single line but is drawn as two for recognition purposes.
Quote
Furthermore, what happens in the following case?
Say a highway is paved with about one meter of paved neutral space, just wide enough for a physical barrier. Down the middle runs a physical barrier, except for a five-mile-long segment where it's just two yellow lines separated by one meter of pavement. The distance between directions of transit doesn't change, the highway design characteristics are otherwise the same, it's just missing a barrier. Is it still a divided highway?
The portion missing a barrier would be an undivided highway, even though all other design characteristics remain the same.
Quote from: roadfro on April 25, 2012, 05:54:45 AM
Quote from: Beltway on April 24, 2012, 01:14:30 PM
On the other hand, a road with a 4-foot-wide separater that has a mountable curb, I would consider to be an undivided highway. Left turns would have to stop in the left lane until opposing traffic cleared.
You're saying a positive (although mountable) curb--thus a positive and physical barrier--would be considered an undivided highway? But a TWLTL--a simple non-positive division--makes a road a divided highway? This doesn't make any sense...
A 4-foot-wide mountable curb island is not a "positive and physical barrier", it effectively is no barrier at all.
Quote from: Beltway on April 25, 2012, 06:23:29 AM
Quote from: roadfro on April 25, 2012, 05:54:45 AM
Quote from: Beltway on April 24, 2012, 01:14:30 PM
On the other hand, a road with a 4-foot-wide separater that has a mountable curb, I would consider to be an undivided highway. Left turns would have to stop in the left lane until opposing traffic cleared.
You're saying a positive (although mountable) curb--thus a positive and physical barrier--would be considered an undivided highway? But a TWLTL--a simple non-positive division--makes a road a divided highway? This doesn't make any sense...
A 4-foot-wide mountable curb island is not a "positive and physical barrier", it effectively is no barrier at all.
Until now, I missed the 4-foot part. A 4-foot mountable curb island is not wide enough to store a left-turning or broken-down vehicle, whereas a TWLTL does have that capacity.
But I would still say that a TWLTL does not truly divide traffic, as opposing traffic can legally share the same space.
Quote from: kphoger on April 25, 2012, 09:57:16 AM
Quote from: Beltway on April 25, 2012, 06:23:29 AM
A 4-foot-wide mountable curb island is not a "positive and physical barrier", it effectively is no barrier at all.
Until now, I missed the 4-foot part. A 4-foot mountable curb island is not wide enough to store a left-turning or broken-down vehicle, whereas a TWLTL does have that capacity.
But I would still say that a TWLTL does not truly divide traffic, as opposing traffic can legally share the same space.
Well no ... it is not an active lane, and if a vehicle is stopped waiting to turn, an opposing vehicle has no legal grounds to occupy the same space of the stopped vehicle.
OK, I didn't mean the exact same square foot. Physically speaking, it's impossible for two vehicles to share the same space. What I mean is that it is both legal and practicable for both directions to enter the same lane at the same time, which is exactly what the term 'divided highway' implies cannot happen.
Not only that, but say there's a northbound car in the TWLTL, waiting to turn left. There's exactly as much division between that car and opposing southbound traffic as there would be on any undivided road -- yellow lines painted on the ground.
Quote from: kphoger on April 25, 2012, 04:30:35 PM
OK, I didn't mean the exact same square foot. Physically speaking, it's impossible for two vehicles to share the same space. What I mean is that it is both legal and practicable for both directions to enter the same lane at the same time, which is exactly what the term 'divided highway' implies cannot happen.
It is not a traffic lane. It is a left turn storage area. A prudent driver knows that he should not slam into a vehicle that is stopped there.
I know of several states (NC, VA, SC, PA) who denote such highways on their state maps as divided highways.
'Divided highway' means that there is separation between opposing traffic.
In that case, any highway with a double yellow line counts.
There's an important distinction between a divided highway that people are missing: left turns are impossible except at intersections with a break in the divider. If there's nothing but paint separating traffic, this does not occur, and the road cannot be considered divided.
Quote from: deanej on April 26, 2012, 11:16:25 AM
In that case, any highway with a double yellow line counts.
That is an undivided highway.
Quote
There's an important distinction between a divided highway that people are missing: left turns are impossible except at intersections with a break in the divider. If there's nothing but paint separating traffic, this does not occur, and the road cannot be considered divided.
Traffic engineers believe otherwise. A 10+ foot wide continuous flush paved divider indeed provide a divided highway. Again, look at the legend for such highways on state highway maps.
^^^
Methinks the two of you are arguing about an official definition (traffic engineers) versus a practical one (driving public).
I generally go with the practical which, in this case, is that if you can make a left turn or u-turn anywhere, then the highway is not fully divided.
Quote from: mightyace on April 26, 2012, 06:25:25 PM
I generally go with the practical which, in this case, is that if you can make a left turn or u-turn anywhere, then the highway is not fully divided.
I
can make a U-turn, quite safely, on the unpaved medians of many interstates. I-8 between Yuma and El Centro comes to mind as having many such zones. Indeed, one can see the tire marks, and also cops like to park in them because they can accelerate out without too much trouble.
Quote from: mightyace on April 26, 2012, 06:25:25 PM
^^^
Methinks the two of you are arguing about an official definition (traffic engineers) versus a practical one (driving public).
I generally go with the practical which, in this case, is that if you can make a left turn or u-turn anywhere, then the highway is not fully divided.
I am thinking more of the rural highways, where the ability to turn left into a field entrance would be widely spaced and the likelyhood of two opposing vehicles needing to use the same left-turn space would be near the vanishing point.
Quote from: Beltway on April 26, 2012, 09:23:10 PM
Quote from: mightyace on April 26, 2012, 06:25:25 PM
^^^
Methinks the two of you are arguing about an official definition (traffic engineers) versus a practical one (driving public).
I generally go with the practical which, in this case, is that if you can make a left turn or u-turn anywhere, then the highway is not fully divided.
I am thinking more of the rural highways, where the ability to turn left into a field entrance would be widely spaced and the likelyhood of two opposing vehicles needing to use the same left-turn space would be near the vanishing point.
Hmm, maybe something like US-45 between Harrisburg and Muddy, IL? Interestingly, Rand McNally shows this as an undivided highway even though I emailed a correction to them years ago. Of course, they still show it as undivided all the way to Eldorado, even though it has a grassy median, wide paved shoulders, and a 65 mph speed limit north of Muddy. :rolleyes:
http://binged.it/K3JI2G (http://binged.it/K3JI2G)
However, the line between widely spaced and not widely spaced is a fuzzy one, so where exactly do you draw the line? Here is an example from IL-33 between Effingham and Shumway. It's a rural area, but housing developments are popping up along in there. I seem to recall the speed limit being 50 or 55 mph through this stretch, but that was a few years ago. I think it's quite reasonable to assume that opposing traffic could have a head-on while both trying to use the center turn lane. But, other than the density of houses, there's not much difference between this one and the one north of Harrisburg.
http://binged.it/K3K2hK (http://binged.it/K3K2hK)
Quote from: Beltway on April 26, 2012, 02:23:06 PM
Quote from: deanej on April 26, 2012, 11:16:25 AM
There's an important distinction between a divided highway that people are missing: left turns are impossible except at intersections with a break in the divider. If there's nothing but paint separating traffic, this does not occur, and the road cannot be considered divided.
Traffic engineers believe otherwise. A 10+ foot wide continuous flush paved divider indeed provide a divided highway. Again, look at the legend for such highways on state highway maps.
Traffic Engineer != Cartographer
A traffic engineer will tell you a divided highway is one where the two directions of travel are physically separated, and vehicles would not physically (or legally) be able to cross the separation or neutral area.
A cartographer or map maker may not make this distinction, and depending on the legend used on the map, may not wish to make a roadway several line types if the characteristics of the road change in order to make the final product easier for the user to comprehend.
why do cartographers place so much importance on divided highways? I'd rather know if it was multiple lanes in the same direction, and also if the mainline is ever required to stop. mapmakers show arterials (lots of traffic lights) the same way as expressways (no stops on the mainline, the occasional left turn and driveway access) and I certainly know which one I'd rather take...
but they make the distinction between four-lane divided, and four-lane undivided, which I don't care about in the slightest.
Quote from: agentsteel53 on April 27, 2012, 11:51:46 AM
why do cartographers place so much importance on divided highways? I'd rather know if it was multiple lanes in the same direction, and also if the mainline is ever required to stop. mapmakers show arterials (lots of traffic lights) the same way as expressways (no stops on the mainline, the occasional left turn and driveway access) and I certainly know which one I'd rather take...
but they make the distinction between four-lane divided, and four-lane undivided, which I don't care about in the slightest.
Maybe because you can see if the highway is divided from an aerial photograph, but seeing if there are stop signs would require driving it.
Quote from: kkt on April 27, 2012, 12:30:38 PM
Maybe because you can see if the highway is divided from an aerial photograph, but seeing if there are stop signs would require driving it.
or you can just zoom in one level more. striping of the road shows fairly obviously where the stop lines are.
Quote from: kphoger on April 25, 2012, 04:30:35 PM
OK, I didn't mean the exact same square foot. Physically speaking, it's impossible for two vehicles to share the same space. What I mean is that it is both legal and practicable for both directions to enter the same lane at the same time, which is exactly what the term 'divided highway' implies cannot happen.
That's only your opinion. It's not a traffic lane. Look at it as a paved left shoulder that is 10+ feet wide
Quote from: roadfro on April 27, 2012, 11:42:26 AM
Quote from: Beltway on April 26, 2012, 02:23:06 PM
Traffic engineers believe otherwise. A 10+ foot wide continuous flush paved divider indeed provide a divided highway. Again, look at the legend for such highways on state highway maps.
Traffic Engineer != Cartographer
They get the design definitions from traffic engineers.
Quote
A traffic engineer will tell you a divided highway is one where the two directions of travel are physically separated, and vehicles would not physically (or legally) be able to cross the separation or neutral area.
Unless there is a median barrier, it will be physically possible to cross the median.
If the median has crossovers, there will be places where vehicles will be able to cross the median. It would be physically possible for 2 vehicles to collide head-on in the crossover.
Quote from: Beltway on April 27, 2012, 02:00:20 PM
Quote from: roadfro on April 27, 2012, 11:42:26 AM
Quote from: Beltway on April 26, 2012, 02:23:06 PM
Traffic engineers believe otherwise. A 10+ foot wide continuous flush paved divider indeed provide a divided highway. Again, look at the legend for such highways on state highway maps.
Traffic Engineer != Cartographer
They get the design definitions from traffic engineers.
Quote
A traffic engineer will tell you a divided highway is one where the two directions of travel are physically separated, and vehicles would not physically (or legally) be able to cross the separation or neutral area.
Unless there is a median barrier, it will be physically possible to cross the median.
If the median has crossovers, there will be places where vehicles will be able to cross the median. It would be physically possible for 2 vehicles to collide head-on in the crossover.
That is very interesting considering that School bus laws in Florida consider a center turn suicide lane as a median, so vehicles on the opposite side of the lane are exempt from stopping for the bus.
I also remember that many map makers showed US 17, 92, and 441 throughout most of Orlando as being divided when most is not. Before the section from Taft- Vineland Road to Osceola Parkway was widened to six lanes and the grass median added, it had a three foot paved buffer in between the two directions of travel. No turn lane then, just an area not designated for travel and more of just a cushion than anything. Still from Taft- Vineland Road to Oak Ridge Road it is undivided and shown as divided.
Quote from: Beltway on April 27, 2012, 01:53:34 PM
Quote from: kphoger on April 25, 2012, 04:30:35 PM
OK, I didn't mean the exact same square foot. Physically speaking, it's impossible for two vehicles to share the same space. What I mean is that it is both legal and practicable for both directions to enter the same lane at the same time, which is exactly what the term 'divided highway' implies cannot happen.
That's only your opinion. It's not a traffic lane. Look at it as a paved left shoulder that is 10+ feet wide
Then I guess I'll start looking at the few inches between parallel solid yellow lines as a paved left shoulder. Unless there's some magic number between zero and ten feet that suddenly turns an undivided highway into a divided highway, that is.
It all up to interpertation as map makers do not know the conditions.
Look at US 209 between i-80 and PA 33 near Stroudsburg, PA? All maps show it as a freeway, yet it is only a limited access expressway with three at grade intersections and the last time I was there in 03, two of them were signalized. Only where it crosses its own business route is a freeway condition present as there is un-interchanged grade separation there. That is just a few hundered feet south of I-80 where the expressway ends to be concurrent with I-80.
Quote from: roadman65 on April 27, 2012, 02:34:27 PM
That is very interesting considering that School bus laws in Florida consider a center turn suicide lane as a median, so vehicles on the opposite side of the lane are exempt from stopping for the bus.
The fuck? No they don't. http://www.leg.state.fl.us/Statutes/index.cfm?App_mode=Display_Statute&Search_String=&URL=0300-0399/0316/Sections/0316.172.html "an unpaved space of at least 5 feet, a raised median, or a physical barrier"
Quote from: NE2 on April 27, 2012, 03:28:54 PM
Quote from: roadman65 on April 27, 2012, 02:34:27 PM
That is very interesting considering that School bus laws in Florida consider a center turn suicide lane as a median, so vehicles on the opposite side of the lane are exempt from stopping for the bus.
The fuck? No they don't. http://www.leg.state.fl.us/Statutes/index.cfm?App_mode=Display_Statute&Search_String=&URL=0300-0399/0316/Sections/0316.172.html "an unpaved space of at least 5 feet, a raised median, or a physical barrier"
That's as may be for Florida, but I know some states do consider a paved median to nullify the requirement to stop for an oncoming emergency vehicle and/or school bus.
Quote from: kphoger on April 27, 2012, 02:36:12 PM
Quote from: Beltway on April 27, 2012, 01:53:34 PM
That's only your opinion. It's not a traffic lane. Look at it as a paved left shoulder that is 10+ feet wide
Then I guess I'll start looking at the few inches between parallel solid yellow lines as a paved left shoulder. Unless there's some magic number between zero and ten feet that suddenly turns an undivided highway into a divided highway, that is.
No. A road with a double yellow line separating opposing traffic is the definition of an undivided highway.
The 10+ feet flush median is the point at which a truck or bus could stop there and be out of the traffic lanes and not be blocking the left lane. It is also 10+ feet separating opposing traffic rather than 12 inches. A divided highway.
If the separator is narrow enough that a left turning vehicle will block the left lane, it is an undivided highway.
Quote from: Beltway on April 27, 2012, 04:02:18 PM
Quote from: kphoger on April 27, 2012, 02:36:12 PM
Quote from: Beltway on April 27, 2012, 01:53:34 PM
That's only your opinion. It's not a traffic lane. Look at it as a paved left shoulder that is 10+ feet wide
Then I guess I'll start looking at the few inches between parallel solid yellow lines as a paved left shoulder. Unless there's some magic number between zero and ten feet that suddenly turns an undivided highway into a divided highway, that is.
No. A road with a double yellow line separating opposing traffic is the definition of an undivided highway.
The 10+ feet flush median is the point at which a truck or bus could stop there and be out of the traffic lanes and not be blocking the left lane. It is also 10+ feet separating opposing traffic rather than 12 inches. A divided highway.
If the separator is narrow enough that a left turning vehicle will block the left lane, it is an undivided highway.
So the division is at 10 feet? A 9-foot paved neutral space would make the road undivided?
Quote from: kphoger on April 27, 2012, 04:15:36 PM
Quote from: Beltway on April 27, 2012, 04:02:18 PM
A road with a double yellow line separating opposing traffic is the definition of an undivided highway.
The 10+ feet flush median is the point at which a truck or bus could stop there and be out of the traffic lanes and not be blocking the left lane. It is also 10+ feet separating opposing traffic rather than 12 inches. A divided highway.
If the separator is narrow enough that a left turning vehicle will block the left lane, it is an undivided highway.
So the division is at 10 feet? A 9-foot paved neutral space would make the road undivided?
I'm not claiming where the exact point is. The maximum normally allowed width of a truck or bus is 8.5 feet. Take it from there as to what it would need.
Quote from: agentsteel53 on April 27, 2012, 11:51:46 AM
why do cartographers place so much importance on divided highways? I'd rather know if it was multiple lanes in the same direction, and also if the mainline is ever required to stop. mapmakers show arterials (lots of traffic lights) the same way as expressways (no stops on the mainline, the occasional left turn and driveway access) and I certainly know which one I'd rather take...
but they make the distinction between four-lane divided, and four-lane undivided, which I don't care about in the slightest.
True, it's especially annoying when parkways (slow speed landscaped roads) are marked as divided highways simply because there's a median.
Quote from: agentsteel53 on April 27, 2012, 11:51:46 AM
why do cartographers place so much importance on divided highways? I'd rather know if it was multiple lanes in the same direction, and also if the mainline is ever required to stop. mapmakers show arterials (lots of traffic lights) the same way as expressways (no stops on the mainline, the occasional left turn and driveway access) and I certainly know which one I'd rather take...
It kinda makes a big difference if you need to make a left turn into a house or business.
Quote from: deanej on April 27, 2012, 09:15:19 PM
Quote from: agentsteel53 on April 27, 2012, 11:51:46 AM
why do cartographers place so much importance on divided highways? I'd rather know if it was multiple lanes in the same direction, and also if the mainline is ever required to stop. mapmakers show arterials (lots of traffic lights) the same way as expressways (no stops on the mainline, the occasional left turn and driveway access) and I certainly know which one I'd rather take...
It kinda makes a big difference if you need to make a left turn into a house or business.
Yes, and also the difference between standing in the left lane behind you, and not standing in the left lane behind you. BIG difference...
If you can't make a turn because something is divided, you have to alter your route. Not "want to" alter your route, HAVE TO.
How would you feel if maps worked the way you want them to, you planned a route based on one, only to find that the place you're going to is on the left side of a divided highway and you can't turn into it's driveway, thereby having to navigate your way around local streets you never planned to go on to find a place to turn around and get on the other side? These days you can check in Google (for the most part; some areas have no street view with blurry satellite imagery), but that wasn't always the case.
I would say that a divider or double line would be used for a situation when widening a highway that is going through a sensitive area (historic downtown, dense residential development) where the extra right of way cannot be bought, or wouldn't be feasible. A median would be best served where the highway is in an open area, and the highway is expected to have higher travel speeds. On US 190, the highway is a mix of undivided and divided sections between Opelousas, LA and Port Allen, LA. Speeds also differ because of the road type.
I find the difference to be that if you can cross the yellow line and not be in an opposing lane, it is divided, no matter the width of the median (raised curb or full blown freeway-size median). If you cross the yellow line and immediately are at harm of getting hit, then it is undivided. It's really a choice thing, in my opinion. I prefer divided highways in a residential area with a median of 1-2 feet (enough for foliage and landscaping), and undivided in a downtown setting.
the amount of time wasted trying to find the next u-turn point is probably a hell of a lot less than the time wasted realizing your expressway is really an arterial with a traffic signal every 300 feet.
Quote from: Beltway on April 27, 2012, 05:42:39 PM
Quote from: kphoger on April 27, 2012, 04:15:36 PM
Quote from: Beltway on April 27, 2012, 04:02:18 PM
A road with a double yellow line separating opposing traffic is the definition of an undivided highway.
The 10+ feet flush median is the point at which a truck or bus could stop there and be out of the traffic lanes and not be blocking the left lane. It is also 10+ feet separating opposing traffic rather than 12 inches. A divided highway.
If the separator is narrow enough that a left turning vehicle will block the left lane, it is an undivided highway.
So the division is at 10 feet? A 9-foot paved neutral space would make the road undivided?
I'm not claiming where the exact point is. The maximum normally allowed width of a truck or bus is 8.5 feet. Take it from there as to what it would need.
And that is the problem with including calling a road with a TWLTL a divided highway... There is no defined point at which there is a physical separation. A raised median, guard rail, jersey barrier, cable barrier, unpaved neutral area, landscape buffer all present the physical separation between opposing flows of traffic that is clearly not meant for vehicles to travel upon. A TWLTL, by definition of it being a turn lane, lacks separation between opposing flows of traffic, no matter how wide the turn lane is.
Quote from: roadfro on April 28, 2012, 02:52:09 PM
And that is the problem with including calling a road with a TWLTL a divided highway... There is no defined point at which there is a physical separation. A raised median, guard rail, jersey barrier, cable barrier, unpaved neutral area, landscape buffer all present the physical separation between opposing flows of traffic that is clearly not meant for vehicles to travel upon. A TWLTL, by definition of it being a turn lane, lacks separation between opposing flows of traffic, no matter how wide the turn lane is.
A 10- to 12-foot paved median does indeed separate opposing traffic. By painted lines and signs, it is clearly denoted for left turns only, that it is not a traffic lane.
As for physical separation, a grass median is not a physical barrier, and a vehicle could easily turn across it if the driver ignores the law.
The separation point at left edge of the left lane on any road is clearly defined by a painted yellow line.
There is a difference between "separation" and "barrier". A grass median is separated even though there's no barrier.
As for the expressway thing... I wouldn't know. By your definition, NY has no expressways, and the closest stuff we've got has traffic lights etc. and were built in the last 20-30 years.
It's rather pedantic to say that someone could cross a grass median. Practically speaking, nobody does; there is usually a ditch in the center and people fear getting stuck in either that or the mud. Even people determined to cross the median will find a graded or paved crossover. Hell, Beltway, your definition on page one is so stringent it would make the Indian Nation Turnpike "undivided" (it has a grass median narrower than a turn lane with no barrier) and that's ludicrous, as it is a fully access-controlled freeway facility with a speed limit of 75 MPH.
For that matter, someone could ramp their pickup truck up on a raised median island and cross over that, too. But nobody that's not a complete asshole would try to do that.
Quote from: Beltway on April 28, 2012, 04:09:52 PM
A 10- to 12-foot paved median does indeed separate opposing traffic. By painted lines and signs, it is clearly denoted for left turns only, that it is not a traffic lane.
I'm confused by this insistence that traffic turning left does not count as traffic.
Quote from: Kacie Jane on May 01, 2012, 01:02:29 AM
Quote from: Beltway on April 28, 2012, 04:09:52 PM
A 10- to 12-foot paved median does indeed separate opposing traffic. By painted lines and signs, it is clearly denoted for left turns only, that it is not a traffic lane.
I'm confused by this insistence that traffic turning left does not count as traffic.
It is not a general purpose lane, it is only used briefly for turning traffic.
I'm confused by this insistence of a few that there is no difference between a 4-lane highway with only a double yellow paint line dividing, and a a 4-lane highway with a 12-foot paved flush median. That is what they are saying when they assert that the latter is "undivided".
Quote from: Beltway on May 01, 2012, 08:12:48 AM
Quote from: Kacie Jane on May 01, 2012, 01:02:29 AM
I'm confused by this insistence that traffic turning left does not count as traffic.
I'm confused by this insistence of a few that there is no difference between a 4-lane highway with only a double yellow paint line dividing, and a a 4-lane highway with a 12-foot paved flush median.
I agree that both assertions go against common sense. But I still see no place at which to draw the proverbial line. And, if we're talking about mapmakers here, then we need specific criteria. 'Large enough to store a left-turning vehicle' isn't good enough, unless you expect a mapmaker to drive out there, park his vehicle in the neutral space, and wait to see if anyone smacks his car into smithereens.
Is there a difference between only a double line and a 12-foot paved neutral space? Of course. But is there a difference between an 8-foot and a 10-foot paved neutral space? Well, that's a little stickier. And I'm not sure we would all feel comfortable with the 8-foot-divided road and the 10-foot-divided road being labelled differently on maps.
Another question to resolve: Is there a difference between a paved neutral space with yellow slashes, one with occasional left-turn lanes bitten into it, and a continuous shared left-turn lane? Common sense would tell us there is some difference, but it's up to debate whether the difference is substantial enough to warrant a distinction in (a) speed limit and (b) map symbol.
I would say that there's a much greater difference between roads with a median divider and a shared left turn lane than those with a shared left turn lane and those that are undivided with only general travel lanes.
Quote from: deanej on May 01, 2012, 11:55:00 AM
I would say that there's a much greater difference between roads with a median divider and a shared left turn lane than those with a shared left turn lane and those that are undivided with only general travel lanes.
I agree. An undivided highway means that a left turning vehicle slows and perhaps stops in the left lane before turning, which is an obvious safety issue on a 4-lane highway. A 12-foot paved median obviates that, and in addition provides 12 feet separation between oncoming general purpose lanes.
As far as mapmakers knowing exactly how wide the paved median is, the DOT will have as-built design plans at minimum, and many have cross-section (and other pertinent) data on an inventory information system.
The FHWA and MUTCD websites don't seem to answer the issue here, as to the exact definition of a divided highway.
One possible solution for mapmakers is to use the number of lanes rather than whether there's a median. A rural four-lane with a center turn lane is much better than a two-lane divided, and even a four-lane with just a centerlne is better than a two-lane.
Quote from: NE2 on May 01, 2012, 12:35:02 PMtwo-lane divided
if you mean "one lane each direction", like CA-37, then that is the worst type of road out there!
Quote from: NE2 on May 01, 2012, 12:35:02 PM
One possible solution for mapmakers is to use the number of lanes rather than whether there's a median. A rural four-lane with a center turn lane is much better than a two-lane divided, and even a four-lane with just a centerlne is better than a two-lane.
In my experience, that's generally how i've seen it done. I most often see references to multi-lane roads as opposed to divided highways. For limited-access roads, Rand McNally generally uses their typical free or toll markings but uses "two lanes" as text to distinguish between the four-or-more-lane routes those symbols usually designate.
Quote from: Beltway on May 01, 2012, 12:19:16 PM
As far as mapmakers knowing exactly how wide the paved median is, the DOT will have as-built design plans at minimum, and many have cross-section (and other pertinent) data on an inventory information system.
No, we're still left with the issue of where to draw the line. I also refer back to my not-so-hypothetical situation where a road was median-divided for most of its length, but where part of it is missing the barrier and leaving only a 1-meter gap in the center. I say this is not so hypothetical by referring you to the following:
Grassy median http://g.co/maps/resc2 (http://g.co/maps/resc2)
Disappears in favor of a median drainage ditch http://g.co/maps/a5rjr (http://g.co/maps/a5rjr)
Disappears in favor of paved neutral space of approx. 0.5 to 1 meter http://g.co/maps/n69r2 (http://g.co/maps/n69r2)
Gains a central barrier http://g.co/maps/ta6su (http://g.co/maps/ta6su)
Goes back to a grassy median http://g.co/maps/ggw54 (http://g.co/maps/ggw54)
Total length of this GMSV jaunt: less than 6 miles
Quote from: Beltway on May 01, 2012, 08:12:48 AM
Quote from: Kacie Jane on May 01, 2012, 01:02:29 AM
Quote from: Beltway on April 28, 2012, 04:09:52 PM
A 10- to 12-foot paved median does indeed separate opposing traffic. By painted lines and signs, it is clearly denoted for left turns only, that it is not a traffic lane.
I'm confused by this insistence that traffic turning left does not count as traffic.
It is not a general purpose lane, it is only used briefly for turning traffic.
I'm confused by this insistence of a few that there is no difference between a 4-lane highway with only a double yellow paint line dividing, and a a 4-lane highway with a 12-foot paved flush median. That is what they are saying when they assert that the latter is "undivided".
A TWLTL, while certainly not a general purpose lane, is also certainly not equivalent to a true median or a shoulder. While medians/shoulders
can be used for storing turning vehicles, they're not necessarily intended to be -- they're intended to store disabled vehicles, and to provide separation (from either opposing traffic, or to provide a buffer between the roadway and the trees). That's the exact opposite of a TWLTL, where the explicit purpose is to store turning vehicles -- actively moving traffic -- but it provides a buffer more by coincidence.
Note that I am not saying there's no difference between a four-lane road with nothing but a yellow centerline and a four-lane road with a TWLTL. Certainly there is. But there is also a difference between the latter and a four-lane road divided by a median/barrier that traffic is not allowed to cross. (No comment on the side discussion of whether one is automatically better than the other.)
Quote from: kphoger on May 01, 2012, 03:25:49 PM
Quote from: Beltway on May 01, 2012, 12:19:16 PM
As far as mapmakers knowing exactly how wide the paved median is, the DOT will have as-built design plans at minimum, and many have cross-section (and other pertinent) data on an inventory information system.
No, we're still left with the issue of where to draw the line.
I don't know and it's really not my issue.
Modern standards would be 12 feet, that is what I have seen in Virginia of the projects built in the last 20 years. That is clearly wide enough to be a divided highway. Older roads with 10 feet would be wide enough as well, as the maximum width of a truck or bus is 8.5 feet.
Quote from: Kacie Jane on May 01, 2012, 05:04:45 PM
A TWLTL, while certainly not a general purpose lane, is also certainly not equivalent to a true median or a shoulder. While medians/shoulders can be used for storing turning vehicles, they're not necessarily intended to be -- they're intended to store disabled vehicles, and to provide separation (from either opposing traffic, or to provide a buffer between the roadway and the trees). That's the exact opposite of a TWLTL, where the explicit purpose is to store turning vehicles -- actively moving traffic -- but it provides a buffer more by coincidence.
I've seen paved flush medians used in rural areas were there are right-of-way constrictions, where it is a median and there are only sparse places where a left turn would be possible.
Also, at a major intersection typically the lane is not "two way", it is painted to be single direction turn lane for 300 to 500 feet before the intersection.
It could be that I'm misunderstanding you (or you misunderstood my previous post), but I don't see how either of those statements contradict anything I said.
Quote from: Kacie Jane on May 01, 2012, 05:04:45 PM
Quote from: Beltway on May 01, 2012, 08:12:48 AM
Quote from: Kacie Jane on May 01, 2012, 01:02:29 AM
Quote from: Beltway on April 28, 2012, 04:09:52 PM
A 10- to 12-foot paved median does indeed separate opposing traffic. By painted lines and signs, it is clearly denoted for left turns only, that it is not a traffic lane.
I'm confused by this insistence that traffic turning left does not count as traffic.
It is not a general purpose lane, it is only used briefly for turning traffic.
I'm confused by this insistence of a few that there is no difference between a 4-lane highway with only a double yellow paint line dividing, and a a 4-lane highway with a 12-foot paved flush median. That is what they are saying when they assert that the latter is "undivided".
A TWLTL, while certainly not a general purpose lane, is also certainly not equivalent to a true median or a shoulder. While medians/shoulders can be used for storing turning vehicles, they're not necessarily intended to be -- they're intended to store disabled vehicles, and to provide separation (from either opposing traffic, or to provide a buffer between the roadway and the trees). That's the exact opposite of a TWLTL, where the explicit purpose is to store turning vehicles -- actively moving traffic -- but it provides a buffer more by coincidence.
This last comment makes me realize that I think that we are confusing 'divided' with 'separated'. A TWLTL or "paved flush median" does not necessarily constitute a division or divided highway in the sense of the physical separation of opposing traffic, where a vehicle would have to cross some non-pavement surface or barrier to enter opposing travel lanes. However, a TWLTL or paved neutral area does provide a buffered separation between those opposing traffic flows that can be traversed relatively easily (whether legal or not). Both could be considered a type of 'median' though. I think it is similar to how the MUTCD defines a difference between barrier-separated and buffer-separated HOV lanes.
In any event, this distinction could possibly explain why lines on maps tend to muddy the difference...