In a motor vehicle accident case, in what circumstances will a plaintiff be held 50% to blame for the collision?

In McDowell v. Barry (1985), 31 N.V.R. 17 (B.C.S.C.), a six year, nine month old plaintiff was held 20% to blame and the defendant motorist that struck him 40% to blame. A second defendant, a contractor whose work truck was parked in such a manner as to obstruct the intersection was also found 40% to blame. The plaintiff's negligence was failing to keep a proper lookout and thereby see warning signs, barricades and traffic cones and in approaching the intersection too quickly in the circumstances.