Strange White and Black Lane Markers on Michigan Freeways Have a Very Specific Purpose
It's part of highway infrastructure you probably would never give a second thought - the lines that divide lanes on highways. But look at them next time you travel. Are they just white lines or are they both black and white?
Some freeways across Michigan have different pavement striping and that lane marking is done deliberately.
The stretch of highway shown above is from Interstate 75 in Metro Detroit. Notice that the lanes there are divided by both black and white lines.
If you don't drive in large urban areas, you may not have ever seen lines on highways like this. The reason is the white/black combination is generally used only in areas where the highways are several lanes across.
The subject came up recently when the Indiana Department of Transportation mentioned the new black/white line scheme on a section of the very busy and wide Interstate 80/94 through Lake County just outside of Chicago. That stretch of freeway, the Boreman Expressway, is among the most congested in the country when it comes to truck traffic.
Have you noticed the black lane markings on I-94 in Lake County?
Last year, our Design Manual was updated to include black markings in combination with the white or yellow markings at some freeway system interchanges or freeway segments with eight or more continuous lanes. The Borman falls into this category so the pavement markings are being updated as part of the concrete restoration project.
In Michigan, there are official guidelines created by the state's Department of Transportation for using what's known as contrast markings
"Shadow" and "contrast" refer to two methods of helping white pavement markings stand out against light-colored pavement surfaces, such as new concrete. Shadow markings are used to emphasize lane line markings and consist of a non-reflective black "tail" marking placed on the downstream side of each skip. The black markings are readily visible in the daytime against pale pavements, but are not reflective since the white markings will show up well at night (plus black wouldn't reflect well). The standard lengths for shadow markings are 6 foot after each broken lane line skip and 2 foot after any lane drop dotted line skips.
There's plenty to explore on the roads across America like the fabled Turkey Track Road, which includes tracks from turkeys who walked across wet cement over 100 years ago in Central Illinois - the tracks still exist. Check out more roads worth seeking out.
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Gallery Credit: Sarah Jones