I can give you a brief example of how laws looked like at the end of eighteenth and early nineteenth century in Carinthia for state roads, the first comprehensive statute was put in place for the duchy in 1778, which gets some annexes throughout the years, and under the French governance it gets messed up a bit, and then again built up slowly with administrative developments. With that in mind, some of the features (there will be some specific differences between the provinces/duchies):

(1) Drainage and waterways were one of the main concerns, since the gravel road was exposed to the elements, and any interference, blockade etc. of drainage infrastrcture was prohibited. Towns, villages and squares were responsible for state roads within their territores, and private drainage from houses and fields was not allowed to run on the road. No waste disposal, no horse feeding, etc.
(2) There were state officials responsible for state roads, road taxes, and there was a road corvee* (adminstered through local munincipalities), mandatory inspections afer floodings and heavy rainfalls etc.
(3) There were rules of conduct, both to officials and between private parties, where there were statutory punishments for injury and deaths, rules for disorderly conduct, endangerment and harrasment (there is, for example, a specific list of activities that constitute harrasment, like wetting someone with a bucket of water). There were rules for riding and transporting, both in weight and speed, specially over critical sections, so one could get fined if one galloped over the bridge, or transported something too heavy, and even more so if that damaged the infrastructure. Yes, there were road signs for this, some even marked the penalty for breaking them. Transporting carts or waggons too heavy (mid eighteenth century the limit was up at 3,4 tonnes) would result in a fine, unless a cart had a wheel dimensions of 15cm or more, or risk a penalty of 10gld. Oh, yes, and the wider the wheels, the lesser the road tax, since narrower wheels damaged the road significantly more than the wider ones. There were also braking rules on the downslopes.

As the time goes on, the statutes become more compex. So by mid nineteenth century, we have regulations about the width of the cargo, maximum number of horses yoked to two-wheeled cart at four, and eight horses for four-wheeled cart, etc. We see the differentiation between the load, number of horses, number of wheels, and wheel width. For example, two-wheeled cart with wheel-width less than 15cm was limited to 1,7 tonne. Also interesting enough, there were snow chains for the winter, and its usage was likewise regulated. Damaging the road due to improper usage was a no go.

There are two more broad dimensions to this, administrations (state, provincial and local, and their immense developement between 1750-1850 for the needs of early modern state - taxation, conscription, land registers, ... ) which ran this, among other things, and documentation, from tracking the cargo, penalties, taxes, travel papers (this is a wonderfully complex subject as well, with great variations from year to year, or rather decade to decade) ... Just for an example, foreigners with travel papers had to stick to the road as marked on the paper, or risk a fine - goes without saying that there was complex regulation on issuance of travel papers, and it could be costly.