Double Yellow Lines

[US 41]

Why exactly are there double yellow lines on the highway? It would seem that one yellow line would be enough. I mean in long passing zones there aren't double dashed lines. It seems like a lot of money spent on paint would be saved if there was just one line rather than two. By the way, on Google Street View, I've seen many places (such as Latin America) that just have 1 line in the center. I also saw this done in Spain in certain places.

[hotdogPi]

I have rarely seen 1 yellow line in the United States. Still, it's almost always 2.

[US 41]

I have rarely seen 1 yellow line in the United States. Still, it's almost always 2.

I have never seen just 1 yellow line on a road in the United States. Federal Route 16 in Mexico is one route that has just 1 yellow line when both sides are prohibited from passing.
http://goo.gl/maps/hj1Ik

[Revive 755]

A single yellow center line was specifically forbidden with the 2009 edition of the MUTCD.

The best answer as to single versus double center lines in the US is probably that the system just evolved that way.  Though IMHO, a double center line has a better chance of being somewhat visible if the pavement markings are in extremely bad shape.


For those who probably haven't seen it before, a history of striping in the US can be found in this document.

[briantroutman]

The wording of the 1961 and older MUTCDs seems to suggest a paradigm where passing was the norm and a no passing zone was a special condition. Early MUTCDs suggested yellow to draw attention to no passing zones and for centerlines on multi-lane roads, but these weren't rigid requirements, and it seems that states used a confusing array of single and double, broken and solid lines in white, yellow, and sometime bituminous black.

The 1971 MUTCD mandated the centerline standards we still use today, and it would appear that most states and municipalities fell into line within a few years.

Coming from the confusion and disarray of previous decades, I think that mandating the double solid yellow was necessary to very clearly standardize the strictest possible combination (yellow and double and solid), leaving no doubt as to where passing was not allowed.

[Arkansastravelguy]

I've seen single yellow lines in Pennsylvania and Massachusetts.


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[Alex4897]

Pennsylvania uses single lines sporadically on back roads, otherwise I only see single ones in shopping centers where they make up their own standards for pavement markings

[Arkansastravelguy]

I recall seeing the one line roads in PA traveling on I-81. The rural roads under the bridges had one yellow stripe. That was quite a few years ago tho.


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[roadfro]

Reno used to use a lot of single yellow lines. These were on residential and low-volume streets that typically don't have any markings. The yellow line was used in the 50-100 feet leading up to stop and yield lines. Since the 2009 MUTCD came out, these have started being properly marked as double yellows.

[GaryV]

If you only had one line, how do you allow passing for the NB direction (going downhill) and disallow it for the SB direction (going uphill, no sight lines)?

Although I recall that there were single WHITE lines on some city streets when I was growing up.

[US 41]

If you only had one line, how do you allow passing for the NB direction (going downhill) and disallow it for the SB direction (going uphill, no sight lines)?

Although I recall that there were single WHITE lines on some city streets when I was growing up.

You do it the same way it is now. A solid line on one side and a dashed on the other. The only difference is when no passing is allowed for either side there is just one solid yellow instead of 2.

[Mr. Matté]

On the point of cost of painting two yellow lines versus one, paint is (relatively) cheap compared to the rest of the road maintenance cost. I believe the paint trucks have the ability to do both lines at the same time so the extra labor/equipment cost is zero.

[hotdogPi]

Although I recall that there were single WHITE lines on some city streets when I was growing up.

That means both sides of the white line go in the same direction.

[TEG24601]

When I was growing up in Hawaii, they were largely single yellow lines.  Some towns in Washington still have single yellow lines.  The logical reason I found was that each line tells you what each lane can do, and if I had my druthers, dashed lines would be double dashes, so that the logical convention was obvious.

[briantroutman]

I've seen single yellow lines in Pennsylvania and Massachusetts.

Pennsylvania uses single lines sporadically on back roads, otherwise I only see single ones in shopping centers where they make up their own standards for pavement markings

This must be either extremely rare or a practice which has all but disappeared in recent years, because in 25 years of living in PA (and about a decade driving all throughout the state), I don't recall ever seeing a single line, even on the most remote rural roads. (Except, as was mentioned, occasionally in suburban housing developments and shopping centers where the private developer was likely responsible for construction.)

Although I recall that there were single WHITE lines on some city streets when I was growing up.

That means both sides of the white line go in the same direction.

Not necessarily, depending on where and when the single white lines were used. Up until the '60s (and perhaps slightly beyond), there was inconsistency from state-to-state on whether white or yellow was used to separate different directions. Some states didn't use yellow at all until it was mandated.

... if I had my druthers, dashed lines would be double dashes, so that the logical convention was obvious.

I've had that thought, too, but double dashes have their own purpose: marking reversible lanes on multi-lane two-way streets.

[AsphaltPlanet]

Single yellow lines are fairly common on both low volume rural roads, and in urban settings in Ontario:

[jeffandnicole]

There's a few county roads near me with single yellow lines.  The majority of them appear to be 1 line, for some reason, faded away when the other didn't.  One would think it would be easy enough to repaint the stripping, but they've remained single yellow for years.

[PurdueBill]

Short-term single fat yellow lines showed up in the IN 25 construction project at temporary crossovers.  One such line is still in place but the crossover is closed off.

Peabody, Mass was infamous for single yellow center lines into the early 2000s on city-maintained streets.  (Thus at transitions from city to state maintenance the line would change from single to double or vice versa.)  They finally fell in line relatively recently.

[SteveG1988]

Around New Jersey it seems to be the norm for narrow bridges to have a single yellow line.

The double line standard does serve another purpose, adds distance between opposing traffic since it is 3 stripes wide instead of one, giving you a few more inches if your vehicle goes over the line.

[Brian556]

Interestingly, one just appeared in Corinth, Texas on a state road. It's on the Corinth Pkwy overpass over I-35E. A truck hit the bridge from below, and the contractor doing the I-35E project placed a low-profile barrier on one side of the overpass, which narrowed the lanes, so they used a single yellow line in the middle due to limited space.

[jbnv]

Around here, a double yellow line with a turning lane for the other direction on the other side, and a center turn lane ahead, means "When a driver stops here to make a left turn, instead of crossing this yellow line into the turning lane, honk and make road-rage gestures at him until he moves." 

[vdeane]

Both single and double are common in Canada.  I've always wondered what the difference is.

[JakeFromNewEngland]

In many rural Connecticut towns single yellow lines are common on the backroads. I also have wondered the difference.

[Mr_Northside]

Pennsylvania uses single lines sporadically on back roads, otherwise I only see single ones in shopping centers where they make up their own standards for pavement markings

This must be either extremely rare or a practice which has all but disappeared in recent years, because in 25 years of living in PA (and about a decade driving all throughout the state), I don't recall ever seeing a single line, even on the most remote rural roads. (Except, as was mentioned, occasionally in suburban housing developments and shopping centers where the private developer was likely responsible for construction.)

Single-line use on certain municipalities' roads is fairly common in the Pittsburgh area.  While I've never seen them on state roads, and Allegheny County roads use double-yellow, and the City of Pittsburgh is either "double-or-nothing", Ross Township uses (or used to, it's possible they stopped) a lot of them.  I've seen them in Bellevue before.... In fact, there are SO MANY municipalities here, I couldn't even begin to list which ones do or don't.
And it's possible that any or all of them might not anymore....

[CrystalWalrein]

Venice, Florida has several of them.

I know that they exist all over Canada on rural roads, including many lesser provincial roads, but I think they are strictly a municipal feature in Québec, with provincial roads there using double yellows.