Slow down? :laughing:
I'm guessing you may have to use more then the ratchet rake there. You might have to dig the area up and redo the subsoil/base.
Wedge
Wedge is spot on... you don't need asphalt, concrete or to slow down if the base is properly constructed... We have a contact with the local Ayuntamiento (town hall) here in Spain to maintain the local dirt roads (of which there are many), so have quite a lot of experience of dealing with washboarding.
You say that it is an old forestry road put in by loggers? If so I would guess that it was laid in a rush without any proper compaction other than the trucks which were using it. As others have said, corregation (washboarding) can be caused by speed, but it will only happen if the road has not been properly compacted during construction, or if too little material has been used.
My suggestion would be that you need to rip it up back down to the subsoil, grade the subsoil to match the profile of the finished road and then lay the stone back down again - you can re-use the existing stone, but make sure you roll it well (hire a vibrataing roller).
When rolling you need to first roll along the route of the road (straight), and then repeat crossing the camber at an angle (45 degrees). Then grade the road again, wet your stone and once dry enough to avoid sticking to the roller repeat the rolling except this time do three passes, finishing by rolling along the route (straight). The compaction from cross rolling the wet stone if done properly will help prevent the corregations (washboard) forming again.
One important point that may people don't realise - for your first pass with the roller, do NOT have the vibrator switched on - this is often the cause of washbording later on, as the soft material compacts unevenly. You need to roll it first, and then vibra-roll it once it is semi compacted. Likewise we often finish with a roll without the vibrator, as it leaves a better appearance.
You will still need to groom the road periodically to fill pot holes etc..., but be careful not to grade too deep otherwise you will need to hire a roller again!
Hope this helps... :thumbsup:
