
The 'Mechanics' of a gravel road.
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Grading
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Crowning
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Compacting
Sometimes its hard to know what a good job really is. The Gravel Mechanics pride ourselves on our
transparency. We want you to know what makes a great gravel road. We use published reference
standards to guide us in our work to evaluate, fix and maintain gravel roads and driveways. These
standards are from the United States Department of Transportation (USDOT), the Federal Highway
Administration (FHWA), the Wisconsin Department of Transportation (WDOT) and the University of
Wisconsin-Madison Transportation Information Center. While not all of these guidelines are easily
applied to a residential driveway but many of the problems we see are caused by deficiencies found in these reference standards along with the right way to fix them.
If maintenance is done on a gravel road, we have found that most often takes the form of a dump truck delivering gravel and tailgate spreading it. This is when the driver uses chains on their tailgate to limit its opening to 3-5 inches and then raises the dump bed as they drive down the road. If done right you get a nice even layer of new gravel on your road. While it is an important step in fix a road that needs aggregate, it is only a step. Pouring good gravel on a bad road does not fix any problems and usually leaves you frustrated in 2-6 weeks as the bad road comes back leaving you little to show for your money. Fix it right and then maintain it.
Link to Wisconsin transportation bulletins 4, 5 and 11:
https://interpro.wisc.edu/tic/wp-content/uploads/sites/3/2019/12/Bltn_004_Road_Drainage.pdf
https://interpro.wisc.edu/tic/wp-content/uploads/sites/3/2019/12/Bltn_005_Gravel_Roads.pdf
https://interpro.wisc.edu/tic/wp-content/uploads/sites/3/2019/12/Bltn_011_Compaction.pdf
Link to USDOT / FHWA Gravel Roads Maintenance and Design Manual
https://www.epa.gov/sites/default/files/2015-10/documents/2003_07_24_nps_gravelroads_gravelroads.pdf
Here are some examples of gravel roads and driveways that need fixing.
Can you guess the root of the problem?
(Hover over the photo for the answer)


Poor crown, runoff down tire tracks, high shoulders, ditches need to recut


Poor crown, ruts down tire tracks, high shoulders, needs aggregate


Poor crown, potholes in tire tracks, might need aggregate, high shoulders preventing water getting to ditches


Poor crown, potholes, high shoulders, needs culvert, dip or diversion to help move water pooled at shoulder


Poor crown, needs dip or culvert to keep water from pooling


Poor crown, water down tire tracks, high shoulder preventing water getting to ditch, likely needs aggregate


Poor crown, ruts down tire tracks, high shoulders, needs aggregate, possible culvert


Poor crown, aggregate pushed to shoulders

