The HOV lanes in Ontario, and I guess it must be occurring elsewhere too, are separated by a stripped buffer zone from the lane next to it. This is what I mean.
I imagine that the purpose is to keep drivers from the non HOV lanes entering the HOV lane except at designated points along the highway. But if that is the only reason, wouldn’t a solid line serve the purpose just as well? Why waste that 2 ft or so width of road space all along the length of the highway?
I dunno. Around San Francisco Bay, they don’t do that; HOV lanes are only that during rush hour, and the rest of the time it’s just the left lane.
In souther Calif they are somewhat like that, only they use two sets of double yellow lines. What it means is once you enter the car pool lane you are not susposto leave it except at definate locations. Crossing double yellow lines is a violation of the VC.
The USA standard treatments are found in the Federal Highway Administrations’s Manual on Uniform Traffic Control Devices, Chapter 3D, pages 415+ (including diagrams). In Canada, ymmv
Link:
Text:
Section 3D.02 Preferential Lane Longitudinal Markings for Motor Vehicles
Support:
01 Preferential lanes can take many forms depending on the level of usage and the design of the facility. They might be barrier-separated or buffer-separated from the adjacent general-purpose lanes, or they might be contiguous with the adjacent general-purpose lanes. Barrier-separated preferential lanes might be operated in a constant direction or be operated as reversible lanes. Some reversible preferential lanes on a divided highway might be operated counter-flow to the direction of traffic on the immediately adjacent general purpose lanes. See Section 1A.13 for definitions of terms.
02 Preferential lanes might be operated full-time (24 hours per day on all days), for extended periods of the day, part-time (restricted usage during specific hours on specified days), or on a variable basis (such as a strategy for a managed lane).
Standard:
03 Longitudinal pavement markings for preferential lanes shall be as follows (these same requirements are presented in tabular form in Table 3D-1):
Barrier-separated, non-reversible preferential lane—the longitudinal pavement markings for preferential lanes that are physically separated from the other travel lanes by a barrier or median shall consist of a normal solid single yellow line at the left-hand edge of the travel lane(s), and a normal solid single white line at the right-hand edge of the travel lane(s) (see Drawing A in Figure 3D-1).
Barrier-separated, reversible preferential lane—the longitudinal pavement markings for reversible preferential lanes that are physically separated from the other travel lanes by a barrier or median shall consist of a normal solid single white line at both edges of the travel lane(s) (see Drawing B in Figure 3D-1).
Buffer-separated (left-hand side) preferential lane—the longitudinal pavement markings for a full-time or part-time preferential lane on the left-hand side of and separated from the other travel lanes by a neutral buffer space shall consist of a normal solid single yellow line at the left-hand edge of the preferential travel lane(s) and one of the following at the right-hand edge of the preferential travel lane(s):
A wide solid double white line along both edges of the buffer space where crossing the buffer space is prohibited (see Drawing A in Figure 3D-2).
A wide solid single white line along both edges of the buffer space where crossing the buffer space is discouraged (see Drawing B in Figure 3D-2).
A wide broken single white line along both edges of the buffer space, or a wide broken single white lane line within the allocated buffer space (resulting in wider lanes), where crossing the buffer space is permitted (see Drawing C in Figure 3D-2).
Buffer-separated (right-hand side) preferential lane—the longitudinal pavement markings for a full-time or part-time preferential lane on the right-hand side of and separated from the other travel lanes by a neutral buffer space shall consist of a normal solid single white line at the right-hand edge of the preferential travel lane(s) if warranted (see Section 3B.07) and one of the following at the left-hand edge of the preferential travel lane(s) (see Drawing D in Figure 3D-2):
A wide solid double white line along both edges of the buffer space where crossing the buffer space is prohibited.
A wide solid single white line along both edges of the buffer space where crossing of the buffer space is discouraged.
A wide broken single white line along both edges of the buffer space, or a wide broken single white line within the allocated buffer space (resulting in wider lanes), where crossing the buffer space is permitted.
A wide dotted single white lane line within the allocated buffer space (resulting in wider lanes) where crossing the buffer space is permitted for any vehicle to perform a right-turn maneuver.
Contiguous (left-hand side) preferential lane—the longitudinal pavement markings for a full-time or part-time preferential lane on the left-hand side of and contiguous to the other travel lanes shall consist of a normal solid single yellow line at the left-hand edge of the preferential travel lane(s) and one of the following at the right-hand edge of the preferential travel lane(s):
A wide solid double white lane line where crossing is prohibited (see Drawing A in Figure 3D-3).
A wide solid single white lane line where crossing is discouraged (see Drawing B in Figure 3D-3).
A wide solid single white lane line where crossing is permitted (see Drawing C in Figure 3D-3).
Contiguous (right-hand side) preferential lane—the longitudinal pavement markings for a full-time or part-time preferential lane on the right-hand side of and contiguous to the other travel lanes shall consist of a normal solid single white line at the right-hand edge of the preferential travel lane(s) if warranted (see Section 3B.07) and one of the following at the left-hand edge of the preferential travel lane(s) (see Drawing D in Figure 3D-3):
A wide solid double white lane line where crossing is prohibited.
A wide solid single white lane line where crossing is discouraged.
A wide broken single white lane line where crossing is permitted.
A wide dotted single white lane line where crossing is permitted for any vehicle to perform a right-turn maneuver.
It’s even worse where I am. The HOV lane is separated from the regular travel lanes by a paved space as wide or even wider than a lane. So we have three lanes and an HOV lane where we could have five lanes of traffic! If we had five lanes, we wouldn’t need an HOV lane.
In the picture you linked to, if you use full resolution you can see the wording on a small sign about 10% below the top margin and almost dead centre along the left/right axis, and just to the right of the orange, diamond-shaped sign. Specifically, it is a sign explaining what the hatched lines mean - “DO NOT CROSS”.
Why a single, solid line wouldn’t accomplish the same effect is beyond me, too.
My guess would be that because HOV lanes may be traveling at a substantially faster rate of speed than the rest of the lanes you don’t want them side-by-side with no barrier between them.
In some places – I-95 south of Washington comes quickly to mind – the HOV lanes are separate from the regular northbound and southbound lanes, and reverse direction for inbound and outbound commute rush hours.
Because, even though it’s illegal, people will still cross a solid white line. A big wide stripped area will make people a bit less likely to cross it, a sign will help even more.
That’s the bicycle lane.
Are you in Connecticut? Because that’s what the highways around Hartford look like.
That perhaps is the closest explanation. It is just a play on the general psychology perhaps. If it is only a solid line, drivers are prone to drift in and out of the line with not as much guilt as crossing a well marked w-i-d-e space with more striped markings within it. It is like telling the driver that you are crossing this line with full knowledge, and with deliberate intention and that is “WRONG” and you are therefore just “BAD…BAD”!!
I was under the impression that a solid white line was merely telling you that it’s a bad idea to change lanes, and that double white lines are used when changing lanes is expressly forbidden.
IIRC you can’t cross a solid line of any color, I don’t think it’s enforced all that often since it seems that it’s usually a minor safety thing that can be avoided by paying attention. I often see solid white lines for the 30 or so feet before the stop line at an intersection to prevent stopped cars from pulling into unoccupied lanes and risk getting hit by another car that isn’t expecting it and still traveling at full speed. Similarly, I often see them on highway on ramps. They usually try to keep you in your lane until you have a chance to get up to speed and the lane straightens out to bring you parallel with the already moving traffic. Of course, if you see an open spot you’ll likely cross the solid line and take it. I don’t think I’ve ever seen someone get pulled over for that.
During one of the early Harley Anniversary’s in Milwaukee they put up a giant sign that said DO NOT CROSS WHITE LINE. In this case it was a spot where you had to merge. The problem was that there used to be a small curb but years and years of trucks running over it had worn it down to almost nothing. It was that ‘almost’ that tripped up a bike and caused our only fatality that year. There was a white line, she chose to go over it probably would have been fine if it wasn’t for the curb.
Unfortunately, there is still a substantial minority that do it here in Southern California.
On a couple of occasions i’ve narrowly avoided a collision when some douchebag decides that the regular lanes aren’t moving fast enough, and that he’s going to duck into the carpool lane across the double yellow lines.
If all the traffic were moving at about the same speed, it might not be so dangerous. But people usually pull this sort of stunt precisely because the carpool lane is moving faster. It’s pretty scary to be going 70 in the carpool lane and be suddenly confronted by some fucking moron pulling into your lane at 45 miles per hour.
They do that on the I-15 here in San Diego County.
There is even one section where they have a total of 4 carpool lanes; two going north and two going south. But those lanes are separated from each other by a moveable concrete barrier, and they can change the arrangement from 2-2 to 3-1 or 1-3 by moving the barrier with a large truck, sort of like a zipper.
There’s an article about it here.
I think it’s part of a lot of the reasons listed but also it’s because it’s effectively a separate roadway, traveling at a speed unrelated to the main roadway. Giving a buffer lane encase of traffic from one ‘road’ crosses over to the other ‘road’, and allowing emergence maneuvering of either without needed to cross into the actual road path of the other.
Accroding to the Illinois Rules of The Road Book:
That just shifts the question to why is it such a big a deal to stop people moving into (or out of) these lanes (except in the places where they let you, of course)? If you are eligible to be be in the HOV lane, why should you not be able to move into it, and, especially, out of it, as freely (and, of course, with the same precautions) that you can change between other lanes?
I question whether speed difference is all that important a factor. In my experience (on Southern California freeways) the carpool lane usually is not all that much faster than the others (and sometimes slower, presumably because people can’t get out of it). If the regular lanes are locked solid, usually the carpool is solid too, or moving pretty slow.
I disagree.
When i drive in LA, it’s usually me and my wife in the car, and we’ve had lots of occasions where being in the carpool lane has made a huge difference in speed. Sure, there are times when both carpool and regular lanes are moving along quite nicely, but there are times when the carpool lane is much faster.
I just had a look at the SigAlert map of LA-area traffic, and found quite a few places where the speed difference between the regular lanes and the carpool lanes was at least 20 mph. That’s significant. In one case, on the 105, traffic was going 18-20mph in the regular lanes, and 60+ in the carpool lanes. The southbound 5 at Ball Road had 35mph versus 61mph. 405 south around Pacific and Long Beach was 35-40 versus 55-65.
And, for the most part, it’s not like you have to go a long way between entrance points. In the LA area, you rarely need to go more than a couple of miles before you can get on and off the carpool lane. I think having fixed areas is better, because part of the benefit of driving in the carpool lane is not just speed, but the fact that you don’t have to spend as much time worrying about other drivers changing lanes all the time.
The reason is that merging (or even just changing lanes) causes substantial friction, limiting traffic flow and capacity in the lanes from and to which the merge is happening. By reducing the number of points at which cars can merge into the HOV lanes, it increases overall traffic flow and the capacity of the HOV lanes.
