Black and White Road Stripes
May 16, 2012 8:20 AM   Subscribe

What are the deep black stripes on highway lane markings immediately following white stripes?

A local highway* recently had it's white, dashed highway stripes augmented with a deep black strip immediately following each dash. My question is: what are these, why are they there, and what is the technology they support (if any) called?

This is a very recently replaced section of highway, so I don't think this was any sort of repainting effort. There appears to be a bit of adhesive around the edges of each black segment (but not the original white), so I wonder if it's an applied piece of plastic marking. I've got some ideas about what it could be, but I'm not certain on any:

- Masking because the white lines were painted longer than they should have been.
- Something to ensure definitive contrast at the end of each dash to support autonomous vehicles.
- IR reflective segments to support night vision equipment.

I've also emailed MDOT who maintains this highway to ask, but they haven't responded yet. Can any of you explain what these are?

Thanks!

*M-59 in SE Michigan, between M-53 and I-75).
posted by c0nsumer to Travel & Transportation around Utica, MI (10 answers total)
 
Hey, a fellow Michigander!

I've always assumed when I saw that stuff that it was masking because the lines were painted over-long.
posted by kbanas at 8:23 AM on May 16, 2012


As shown on this highway in Virginia, black contrast pavement markings are used on light-colored pavement surfaces by some States to enhance the visibility of lane lines.
posted by weapons-grade pandemonium at 8:26 AM on May 16, 2012 [3 favorites]


I always assumed they had painted (or blacked out) over the old stripes in order to put down new stripes without having to worry about matching up the new stripes with the old.
posted by Grither at 8:26 AM on May 16, 2012


I can tell you it's not #2 or 3. Neither of those functions are supported in the Manual for Uniform Traffic Control Devices (MUTCD).
posted by hwyengr at 8:29 AM on May 16, 2012


My comment should have been italicized, because it is the caption under the photo halfway down this page.
posted by weapons-grade pandemonium at 8:31 AM on May 16, 2012 [1 favorite]


Not knowing what's typical for Michigan highways, is it possible that they're recessed cat's-eyes that have been masked to keep them from being painted over?
posted by hattifattener at 8:40 AM on May 16, 2012


hwyengr: I can tell you it's not #2 or 3. Neither of those functions are supported in the Manual for Uniform Traffic Control Devices (MUTCD).

Would that prohibit the use of such markings, though? I can't really see why something that serves a an auxiliary purpose while not obscuring the primary would be a problem. In reading 3A.02 and 3B.04 (from here) I don't see anything about #2 or #3 (or any other functions) being prohibited, just that the markings need to be retroreflective and consistent.

3A.05 details black as:

Black may be used in combination with the colors mentioned in the first sentence of Paragraph 1 where a light-colored pavement does not provide sufficient contrast with the markings.

and

When used in combination with other colors, black is not considered a marking color, but only a contrast-enhancing system for the markings.

So maybe it really is that simple?
posted by c0nsumer at 8:45 AM on May 16, 2012 [1 favorite]


We have that paint on the new 35W bridge in Minneapolis. The local news stations did all kinds of fluff reports on the paint since so many people are asking.

It helps make the white lines stand out when there is snow on the ground since the road surface is also so light to begin with (even after being plowed).
posted by TinWhistle at 9:39 AM on May 16, 2012


Yes, it's that simple. If it is a construction zone, they will use temporary blackouts over permanently painted lines to either "erase" them, or to convert a solid line into a dashed line.
posted by gjc at 10:22 AM on May 16, 2012


Today I heard back from MDOT, and the response is a bit more mundane. These are, in fact, used to enhance contrast where there may be sun glare, including on light colored pavement. To quote from the received email:

The markings are part of a pilot project aimed at helping motorists see pavement markings during certain times of day when the suns glare/reflection is strong. The black outlines the white making the markings more prominent.

and

As I understand we will be putting more out on MDOT’s road in the next few years in locations where visibility by the sun is diminished.

So, that's that!
posted by c0nsumer at 11:41 AM on May 17, 2012


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