water deflectors on unpaved roads or drives

http://cceonondaga.org/resources/water-deflectors-managing-surface-water-and-reducing-erosion-on-unpaved-roads
from above;
Additional Practices to Stabilize Roads
Installing water deflectors is just one of many practices used to reduce erosion and manage
surface water on unpaved access roads.
Contact your local Soil & Water Conservation District for technical assistance with these other
methods:
∙ Water Boxes ∙ Check Dams
∙ Broad-based Dips ∙ Rock rip rap
∙ Box & Pole Culverts ∙ Geotextiles

I have use deflectors by simply digging a 6 inch wide,1 inch deep trench at an angle across a road.  What I dug out of the trench gets mounded up  as a berm down hill of the trench.  

I wasn't trying to prevent erosion, I was trying to get very slow flowing water from snow melt off the road so it had a chance to start drying underneath and begin to firm up.

Crowning a road or drive way  so water can't stand on it or flow down it but instead is directed to ditches on either side helps a lot.  The steeper the hill your road goes up the more the road should be crowned to so it sheds water top the side faster.

Lowering the water level around a road also helps it firm up.  It is best done with building and MAINTAINING ditches and culverts.  Often ditches are built properly but non maintained as sediment builds up in areas causing the ditch to hold water in areas that water soaks in under the roadbed and weakens it.  On proper roads the ditches may be several feet deep but could be as simple as a few inches deep ditch that give the water a place to flow away from the road.