Top Gun: Moron

Reviews from critics and defenders of a Las Vegas speed demon continue to pour in

Stopping sight distance (SSD) is a critical safety measure in road design and driving. It refers to the total distance a vehicle travels from the moment a driver perceives a need to stop to the point where the vehicle comes to a complete stop.

SSD is the sum of two components: Perception-Reaction Distance and Braking Distance. 

Perception-Reaction Distance 

This is the distance a vehicle travels while the driver recognizes a hazard and decides to apply the brakes. It's calculated using the driver's reaction time and the vehicle's speed. When engineers design roads, they assume a standard reaction time of 2.5 seconds. It sounds like eternity, but that’s what AASHTO and FHWA have been using for years. (There’s probably an argument to be made that with all the modern driver distractions like cell phones and infotainment screens, 2.5 seconds isn’t long enough.)

Braking Distance

This is the distance the vehicle travels from the time the brakes are applied until it comes to a complete stop. It depends on the vehicle's speed, the coefficient of friction between the tires and the road, and the vehicle's weight. 

A heavier vehicle like the Tesla Cybertruck will have a longer braking distance compared to a minivan or even an empty pickup truck.

SSD

[Stopping sight distance] = [(perception reaction distance) + (braking distance)]

Let's say someone piloted their Cybertruck at 83 mph in a residential area with crosswalks, sidewalks, and a posted speed limit of 35 mph. (More on that random number in a second.) The driver would need over 600 feet on dry pavement to come to a complete stop after seeing a potential danger. An engineer using the AASHTO guide would be even more cautious and assume drivers need 900 feet to stop at a design speed of 80 mph.

Two or three football fields. You get the point—stopping sight distance gets real long real quick. Imagine needing to be able to see that far ahead when a person in a wheelchair is about to roll across the street. 

Physics in the news

Earlier this week, a guy named Matt Wallace posted a video of himself driving like an Air Force pilot on a Las Vegas street. Wallace was in the comments talking smack and defending himself.

In local news:

“Cybertruck makes a U Turn using only my pinky. Check mate,” Capt. Wallace posted on his X account on June 2.

The vehicle appeared to reach a speed of 83 miles per hour within ten seconds on the empty residential street before the U-turn. In the video, a sign showing a speed limit of 35 miles per hour on the street is visible.

In response to online criticism about speeding, Wallace replied, “Also you notice there’s not a single car or a single pedestrian on the road? Ya think maybe I was smart enough to reach out to my cop buddies and let em know I was conducting a road test and they have cordoned off the area for me? Nice try buttercup.”

And in UK news:

Las Vegas Metropolitan Police Department told the local news station they are not aware of officers closing streets for Wallace.

They noted they are unable to cite the driver for speeding based on this specific video and said investigations originating from video are handled on a case-by-case basis.

Wallace deleted the original post after the world was talking about him. Most of you missed it. But that’s ok, because some of us saved it. Wallace has also locked his account, because now the Air Force is investigating him. 

Speed is a fundamental factor in every severe crash. Stopping site distance is one reason for that. When people drive fast, especially in heavy vehicles, they don't realize how much space they need to avoid disaster.