To consider an action negligent and therefore find a party responsible for injury, the act would have to be considered reasonably foreseeable.
Therefore just because an accident happens because of another, that doesn’t automatically entitle the victim to compensation. What this means is that a reasonable person has to be able to predict or expect any harmfulness of their actions.
Whether an action was considered reasonably foreseeable was discussed at length in Bolton v Stone  AC 850, in these circumstances the Claimant was hit by a cricket ball outside of her home. She attempted to bring an action against the cricket club for nuisance and negligence. This claim ultimately failed, as necessary precautions were in place, in this instance a 17 foot fence. Plus it was agreed that the shot taken by the batsman was altogether exceptional and like nothing else that had preceded it and in the 70 years that cricket had been played there, a ball had never been hit out of the ground. Therefore the likelihood of harm was not foreseeable by a reasonable person.
On the other hand, if cricket balls were being regularly hit out of the ground this would constitute negligence by the defendant as it was reasonably foreseeable that this may lead to serious injury see Miller v Jackson  and Castle v St Augustine’ Links  where this was the result.
How do we apply this to claims that we deal with on an every day basis as a personal injury company?We will get accidents where a defendant has run a red light or an employer has not provided suitable training or clothing to employers. In these circumstances a reasonable person would anticipate that the chance is there for an accident to occur and the defendant are therefore negligent in these circumstances.
However, this is not a blanket rule; there are exceptions to the rule of reasonable foreseeability. In some circumstances the likelihood of harm may be viewed to be that low that it otherwise would not be considered, but the seriousness of harm is so severe that this supersedes the low likelihood and therefore it has to be viewed as if it was reasonably foreseeable. This happened in the cases of Wagon Mound No.2  and Paris v Stepney  and means that if the activity you are carrying out can have potentially serious implications, then you will not be allowed to neglect this risk however slim the chance is of something unfortunate happening.