Torts — Negligence — Automobile accident — Rear-end collision — By operation of section 337.195(1), plaintiff is presumed to be sole proximate cause of injuries she sustained when she drove her vehicle into rear of cement truck as it drove away from highway construction zone in which defendants were acting as contractors or agents of Florida Department of Transportation where plaintiff was under influence of alcohol at time of crash and action of truck driver in misjudging speed and distance of oncoming traffic into which he merged was not grossly negligent — Defendants are also entitled to summary judgment on alternative ground that plaintiff rear-ended truck and failed to rebut presumption of rear-driver negligence