In Garland v SoS for Environment etc (2021) EWCA Civ 1098 the Court of Appeal says that, in deciding whether the common law dedication of a right of way over land would constitute a public nuisance, as a matter of fact, there is no need of evidence of an actual specific accident or incident. The character of the route itself may justify the inference that the route is potentially dangerous to a section of the public.
However, the lack of such evidence is likely to be very relevant, particularly where there has been extensive use. Moreover, it is not appropriate to speculate about future use and consider whether that might give rise to a public nuisance. Once the right of way is established by dedication, it cannot be retrospectively be held that the landowner had no authority to grant the rights being exercised because of an alteration of the degree or even nature of use, even if there would be an increased risk of an incident.