First of all, you should make sure your bylaws include a damage provision as part of your formula for assessing each member's share of the cost of maintenance.  The law requires that, "The determination of each owner's share of the total cost must be fair and equitable and based upon a formula provided for in the road association's bylaws or adopted by the owners at a meeting called and conducted pursuant to this section." 

At our 2020 MARA conference, our attorneys stressed the importance of making sure you follow the law to the letter, and that includes making sure your method of determining the dues is clearly written into your bylaws.  If it ever came to a  court challenge, you would want a judge to be able to look at your formula and decide that it's "fair and equitable."  If one person causes unusual damage to the road, one would think a judge would see it as fair to make that person pay to repair the damage rather than making everyone else share the cost.

It can be difficult to prove who did damage to the road.  If there is damage, take lots of pictures.  Ruts show up best in photos taken in early morning or in the evening when the light is low so you get a shadow that shows the depth.  Also put a ruler or something in the picture to show the scale.  Zoom in to get a clear picture of any tread marks.  If you can, get a picture of contracting equipment in the background of a picture that shows the damage, and then get closeups of the equipment showing matching tire treads, and license plates or company logos.

For damage by people who pass through on ATV's or 4wd pickups, your best defense is a trail camera, placed so it will clearly show the vehicle and license plate if possible.  It's also good to take pictures before you expect damage, like just before mud season, just before hunting season, just before a holiday weekend when a particular offender has been known to show up before,  just before someone starts building or renovating a house, etc.

We don't define damage as including every day wear and tear, although when you have people who habitually drive in the same two ruts, it's tempting!  We do include things like ruts left by ATV's doing donuts in the gravel, or growser tracks in the pavement where someone unloaded heavy equipment.  If someone orders a delivery of fuel or lumber or other heavy items just as the frost is going out of the road, that can also cause damage.  Try to make sure people plan ahead so this doesn't happen.  Some fuel companies already have this on their radar.

As for assessment, you can either ask the person who damaged the road to repair it, (many contractors plan to set things right and leave things as they found them but don't repair the damage until they're done,) or you can hire someone to repair the damage and add the bill to the annual road association dues with an explanation and a copy of the bill attached.

Another possible technique would be to include in your bylaws a flat surcharge for any construction, or requiring contractors to post a bond.  I am not an attorney, so please take all of the above as just my experience, not legal advice, and consider it for what it's worth.

That's rather vague wording.  I wonder if it ever got challenged in Court whether a judge would see it as passing the "fairness" test.

Our bylaws say, "Any damage to the road by an owner, his/her guests, or his/her contractors beyond normal wear and tear shall be the responsibility of that owner, and the cost of any repairs necessitated by such damage may be assessed against said owner by the Board of Directors."  We did have to use this clause once, when someone's teenage son did donuts in the fresh gravel with an ATV.  With that member's agreement, we hired someone to grade out the ruts with a York rake, and added the cost to that member's dues the following year.  The wording of our bylaws pins the amount of the extra assessment to the cost of the repair of the damage, so there is no question as to what that amount should be.