[2025] EWHC 1844 (KB)

Craig Arnold reported for the Court instructed by the Claimant. His accident reconstruction qualifications were not challenged. He provided a useful plan. His main conclusions and opinions were on only three points.

The rationale for those conclusions was set out in his report and the subject of cross examination. Opinions (1) and (3) were not challenged. Opinion (2) was challenged. I shall concentrate on separation distance, which was the issue. In his conclusion Mr Arnold stated that his calculations were estimates based on assumptions and were indicative. There was no physical evidence to confirm speeds. On AP’s evidence the separation distance was calculated at 34-37m by Mr Arnold. On the separation distance at rest after the accident he calculated 45m of separation. He assumed that the Claimant was travelling at 60 kph or 66 kph on straights 1 and 2 and 20 kph on turn 1. He stated straight 1 was 62-80m long and, on the Claimant’s case, the guide was 62-80m away when the Claimant exited the right-hand bend onto straight 1. He assumed that both the Claimant and the guide turned turn 1 at 20 kph and maintained a constant speed on both straight 1 (62-80m) and straight 2 (18-32m). He took an acceleration factor of 0.7g and calculated that if the Claimant continued to accelerate to the point of impact on turn 2 he would have been going at 92kph on impact. If he had only accelerated for 22.7 m on straight 2, at 0.7g he would have reached 66 kph at impact, which Mr Arnold described as more reasonable. He later wrote “If the Claimant had slowed down from half way along straight 2 he could have turned at 20 kph safely”. To calculate the separation distance Mr Arnold used a reaction time estimate and assumed the Claimant accelerated at 0.7g for half of straight 2 to reach 66 kph and he maintained that speed (C562-563) until impact. He calculated that they would have been 37m apart when the Claimant exited turn 1, so the guide would have been out of sight.

There are some rather fundamental defects in Mr Arnold’s assumptions. Firstly, the Claimant does not assert that he accelerated between turn 1 and turn 2. He cannot recall what he was doing in that period. Secondly, the acceleration factor assumed is at the very highest end. Mr Wright takes a much more likely and lower figure as I shall set out below. Thirdly, for any beginner, even a confident one, to use maximum acceleration after turn 1 on the straight shown below, would be careless in the extreme. The light is better in this photo (taken by Mr Wright), than it was on the night of the crash. This is the view exiting turn 1 and along straight 2. On any basis, with good light or poor, there are large trees straight ahead.

Fourthly, no rational person would continue at 66 kph down straight 2 and the Claimant does not assert such. What he wrote in his witness statement was: “I applied my brake heading into the left-hand turn. I steered to the left and leaned into the turn. I can remember the turn being quite long. I remember negotiating the turn for some time before I lost control of the snowmobile. I remember reaching what I believe to be the apex of the turn before I lost control” I pointed out above that this paragraph did not clearly distinguish between turn 1, straight 2 and turn 2, but one assertion which the Claimant definitely did not make was that he accelerated after turn 1.

Fifthly, as Mr Wright pointed out, the Claimant managed to turn 25 degrees at turn 2 and he would not have been able to make any such turn at 66 kph or 60 kph. He would have run straight off the track without any turn at those speeds. In my judgment, Mr Arnold did not consider this properly. For those reasons and the reasons set out below in cross examination I can place no weight on Mr Arnold’s separation distance reconstruction.

In his verbal evidence in chief, Mr Arnold stated that he attended the site in December 2024. Some trees had been removed in the area. The UTAC representative did not explain which trees. He stated that the Claimant could not have been thrown behind or through the tree which he hit and impact with the tree may have occurred and slowed his progress through the air. His helmet had been scratched. He may have had contact with the SM handlebars. All of this undermined Mr Wright’s throw distance calculations. In his opinion it was not possible to estimate the impact speed from the crash damage photos or the throw distance. He buttressed his reaction time assumptions with various papers showing that human reaction to audible sound was different to visual stimuli. All of this went to a dispute between the experts on the distance between where AP stopped his SM and where AP was when the Claimant hit the tree. The stopping position was eventually agreed at around 30 metres and it was agreed that AP was around 19m in front of the Claimant when the Claimant hit the tree, so I will not consider his evidence any further on these details. In cross examination, he agreed Mr Wright’s critical speed opinions for turn 1 as 38 kph and for turn 2 as 26 kph. He accepted that the Claimant’s likely speed on straight 2 would have been lower than 66 kph and that assuming top acceleration was “unlikely”, so he undermined his own assumptions in his report. He accepted that the relative speed difference between the Claimant and AP during the time from AP’s look back on straight 1 and the crash was the main determining factor of whether the Claimant could see AP when exiting turn 1. He accepted that he had used constant speeds as his assumption and that was also unlikely. He admitted that modelling with certainty was impossible. Mr Arnold accepted that it was possible that the Claimant accidentally gripped the throttle. He accepted that, in the joint report, he had agreed that the Claimant’s view exiting turn 1 would be up to 30 metres towards turn 2 in which to see AP and his red rear lights. He also accepted that the trees would provide a visual reference of there being no track straight ahead where they stood. He accepted that understeer was not a central causative factor or even a factor but he had never ridden a SM. When shown the hospital records of the Claimant, which record that he said he accidentally hit the throttle, he accepted that if this occurred a collision was unavoidable. He accepted that the Claimant navigated turn 1 successfully so must have been travelling at less than 38 kph. It was put to Mr Arnold that the Claimant’s case was that he thought it was one long turn so it would not make sense for him to accelerate on the turn intentionally. Mr Arnold agreed that such acceleration on a turn would be “foolish”. In re-examination Claimant’s counsel sought to open up an alternative case of intentional acceleration followed by accidental throttle application but no application to amend to support that case was ever made.

Mr Wright gave evidence instructed by the Defendant. He works in Ontario and has 30 years of experience. His conclusions were:

In their joint report Mr Arnold and Mr Wright agreed the various distances and the plan and that there were visual clues for the Claimant of the presence of turn 2 when exiting turn 1. Those were: the red tail lights of the guide, if he was visible; the snowbanks either side and the contrast of the trees. Otherwise, they disagreed.

Generally, I was more impressed by Mr Wright’s logic and approach than Mr Arnold’s.