The highway source defaults to one hundred five miles per hour and one point five seconds of perception time. It converts speed to feet per second with multiplier one point four six six six seven, giving about one hundred fifty-four. Reaction travel is speed times perception time, about two hundred thirty-one feet. If perception time becomes one second, travel is about one hundred fifty-four feet. The bars show the linear time dependence in this saved model, not personalized driving advice. Braking distance in the source is speed squared divided by twice the friction factor times thirty-two point one seven four. At one hundred five miles per hour and factor point seven, that is about five hundred twenty-seven feet. Combined with the reaction travel it gives about seven hundred fifty-eight feet. Doubling speed while keeping other inputs fixed would quadruple the braking term, whereas reaction distance only doubles. The source assumes constant deceleration; real road and vehicle conditions require additional evidence. Its obstacle default is three hundred fifty feet. After the modeled two hundred thirty-one feet of reaction travel, only one hundred nineteen feet remain for braking. Subtracting twice friction times gravity times that distance from speed squared leaves an impact-speed estimate about ninety-two point four miles per hour. If the obstacle is farther than total stopping distance, the branch returns zero. This is the saved idealized calculation; the label Safe in the original interface is not a verified safety guarantee.