Who is responsible for the crash?

In the case at hand, the driver of the smaller vehicle seeks compensation for the damage caused to his automobile as a result of a collision with a transporter van. The driver of the transporter (defendant) had the right of way when turning into the smaller street. The claimant alleges that the driver of the transporter miscalculated the angle for taking the turn, which led to the crash, and therefore bears full responsibility for the collision. The defendant argues that the claimant in fact disregarded his right of way and started taking his left turn as the transporter was still completing the turn, which resulted in the front left part of the smaller vehicle hitting the left rear of the transporter. The claimant, therefore, should be fully responsible for the accident. 

Since  both stories diverge on a fact relevant for the court's decision, an expert was summoned to analyse the events based on the surroundings and the actual damage to the vehicles. This is one of his drawings, attached to the file I am working on.