Do not write that the driver was negligent. Write the second and a half.
"Negligent" is a conclusion. It tells the reader what to think without showing them why, and a reader who is told what to think reaches for a reason to disagree. The fix is not a bigger adjective. It is the interval.
An alert driver gets about a second and a half to see a hazard, decide, and get a foot to the brake. Road designers use a longer figure, two and a half seconds, to stay safe for everyone. That interval is not a technicality. It is the whole difference between a driver who could not stop and one who did not. So show it. At this speed the truck covered this many feet every second. The hazard was visible from here. He had four seconds. Now the reader does the math, and the reader who does the math owns the answer.
This is proof over conclusion. You do not tell the jury he was careless. You put them in the cab, start the clock, and let them watch the time run out while he did nothing. The word "careless" asks them to trust you. The second and a half lets them convict him themselves.
The move: hunt every conclusion in your draft, negligent, reckless, unsafe, excessive, and ask what it is standing in for. Behind each one is a measurable thing, a distance, a speed, a count of seconds, a moment the defendant could have acted and did not. Cut the conclusion. Show the interval. Let the reader arrive on their own.
Never write that he failed to react. Show the second and a half he had, and let them feel it pass.
On how long it takes an alert driver to perceive a hazard and brake, see the perception-reaction time literature (Green, "How Long Does It Take to Stop?", Transportation Human Factors, 2000).
