Gravel road construction / maintenance
Gravel road construction / maintenance
(OP)
I live on a remote island in SE Alaska, I serve on a community road committee; we are looking for guidelines and "how to" data to help us specify road improvements.
Our roads are left over logging access roads filled with large rocks and boulders... grading is impossible in the current configuration. I'm not an engineer but spent my 33 year career working with engineers so I have some ideas about how to properly design and maintain things. We have very limited funds; my goal is to repair our roads so that they will be less expensive to maintain thereby leaving dollars in our annual budget to continue road improvements.
Any help will be greatly appreciated by our little community.
Thanks,
Howard
Our roads are left over logging access roads filled with large rocks and boulders... grading is impossible in the current configuration. I'm not an engineer but spent my 33 year career working with engineers so I have some ideas about how to properly design and maintain things. We have very limited funds; my goal is to repair our roads so that they will be less expensive to maintain thereby leaving dollars in our annual budget to continue road improvements.
Any help will be greatly appreciated by our little community.
Thanks,
Howard





RE: Gravel road construction / maintenance
http://www.epa.gov/owow/nps/gravelroads/
..lots of pictures :)
RE: Gravel road construction / maintenance
h
RE: Gravel road construction / maintenance
I note the under-drainage section really is not good for you.
While geotech wrapped drain pipe may work out in your gravel soils, I'd look to minimize frost heave and resulting weak spring conditions by following a few rules I have learned about this.
Keeping your ground water table below the final grade at least 4 feet does wonders. Backfill perforated pipe with clean-coarse sand, similar to concrete sand. Don't use open graded rock since it plugs up.
Any use of under-drains should be placed to cut-off the flow coming towards the subgrade. Drawdown of water table to drains running under the roadway is not usually possible.
People driving fast on gravel roads can cause wash-board surface to develop. Your grading guys should use a deep blade cut when re-shaping the roads, since shallow cuts somehow do not get rid of inherent weaknesses and wash-boarding soon comes back.
When changing road profile, remember the worst frost-susceptible soils are found just below topsoil in what we used to call the B-horizon. You might want to undercut that stuff at least 18 inches, if you can. It's at the change from cut to fill.
Roads with culverts probably will heave up in winter, but culverts won't. To minimize that dip, replace subgade in tapers back away from culvert with non-heaving sand and gravel fill.
RE: Gravel road construction / maintenance
What is the side road drainage like? Fully developed side ditches? If not, then work to get them dug so, as oldestguy suggests, to lower the water table and promote runoff to minimize ponding up into the road. If you have the topography, can even cut very deep trenches with a small excavator and backfill with rock to draw the water down even more - but then drain these trenches off downhill (thinking you might be in a mountainous area). You may get some plugging depending on the nature of the soil - could wrap the french drains with geotextile (too bad you don't have palm hair!! - I've seen it used before). You could also dig a trench down the centre of the road, backfill with gravel as oldestguy has alluded to - then take it off to the side - this will reduce the mounding that occurs between road edge drains. Just some initial thoughts.
RE: Gravel road construction / maintenance
You've given me some good ideas and a good reference resource... now if I can convince our road committee to take a longer term view... just maybe we can eliminate some of the reoccuring problems...
Thanks so much!
RE: Gravel road construction / maintenance
RE: Gravel road construction / maintenance
More expensive would be to hire someone with a portable jaw/crusher to dig up the rock, run it through the jaw and place it back on the road. The last few years there have been a number of equipment manufacturers that have started to sell small, highly mobile, tracked jaws that do a pretty good jaw of crushing down to about 3" minus or so. It would be fairly expensive though, down here about $10,000 per mile, I imagine it would cost you more up there.
RE: Gravel road construction / maintenance
We are currently working on a plan to install a few culverts and try to repair the worst of the pot hole areas before winter snows begin... then work on a mid-range plan for winter snow removal & maintance AND a longer thrm plan for next spring - summer and beyond... the goal is to repair the roads as best as we can with VERY limited funds in such a manner as to reduce maintenance costs thereby allowing us to spend more of our limited budget continually improving the community road system.
Thanks so much for your interest and input...
Howard
RE: Gravel road construction / maintenance
h
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