According to this article from Farming UK, one County Council appears to be taking a proactive approach to avoiding road accidents, by asking the public to report muddy roads to the police.

It's important for drivers of heavy machinery (such as farmers or developers) to be aware that they can be held liable for accidents caused by mud that they deposit on roads. The best and safest way to deal with this issue it to clear the mud from the road as soon as possible.

As well as a potential manslaughter charge for the more unfortunate cases, there are a range offences under the Highways Act 1980 in relation to depositing mud on roads, such as damaging the highway, interrupting users of the highway, and depositing anything on the highway which causes injury.