Tailgating: The Game

Please share this article with someone who might know someone who is inclined to tailgate occasionally.

"Tailgating" is the dangerous tactic of following a car too closely, hoping that this will encourage them to speed up. Roads in my area have a typical speed of 55 miles per hour (mph). I often acquire tailgaters that ride less than three car lengths (about 45 feet) behind my car, and 10 feet behind me is not rare. This is only a small fraction of the safe following distance.

I wish more drivers understood safe following distances and that they understood the utter futility of tailgating.

Below, I have tried to provide some helpful information. ?I have also created a simulator game about tailgating and safe following distances that incorporates the player's reaction time.??

I have also provided the simulator game project code and assets so you can have fun playing with them using the Godot Engine, if you like. Feel free to use it to make the simulator better or to make something else.

In the next sections, I will discuss the physics at play that determine the stopping distance, the safe following distance, the futility of tailgating vs the danger, and provide links to the simulator.

Physics

The total stopping distance of a vehicle is a function of the reaction distance (the distance a car travels in the time it takes its driver to begin braking), plus the braking distance (the length the car needs to decelerate to zero after the brake is activated).?

The reaction time of a driver is highly variable. ?A professional race car driver has a reaction time of about 0.2 – 0.3 seconds. ?An average reaction time is about 0.75 seconds.??? Young people have faster reaction times. ?Older adults have slower times. ?Exhaustion can increase reaction time.? Vision in the dark is affected by other lights, and it is harder to judge what is ahead and when the brake lights ahead come on.?

Of course, reaction times assume that a driver is paying 100% attention. ?If someone glances down at their phone or their car display for 1 or 2 seconds, add this to the above reaction times.

Assuming a 1-second reaction time at 60 miles per hour (88 ft/s) means a reaction distance of ?88 ft. ?Assuming a 0.5-second reaction would mean 44 ft.

American Association of State Highway and Transportation Officials (AASHTO) says that stopping distance is given by this ?formula :

s = (0.278 × t × v) + v2 / (254 × (f + G))

where:

s?– Stopping distance in meters;

t?– Perception-reaction time in seconds;

v?– Speed of the car in km/h;

G?– Grade (slope) of the road, expressed as a decimal. ?Positive for an uphill grade and negative for a downhill road; and

f?– Coefficient of friction between the tires and the road. ?It is assumed to be 0.7 on a dry road and between 0.3 and 0.4 on a wet road.

The first part of the fomula (0.278 × t × v) gives the reaction distance.? The second part (v2 / (254 × (f + G))) gives the braking distance.

Considering only the braking distance, and assuming a dry road and no grade, a car traveling at 60 mph needs a braking distance of 172 ft.? You can see by the formula that the distance goes up at the square of the velocity. ?So, at 70 mph, the braking distance is 234 ft. ?At 85 mph, it is 355 ft, double the distance required at 60 mph.

Braking distances vary by vehicle, but not as much as I thought. ?A Porche 911 has a braking distance of 133 feet at 70 mph (about 100 ft at 60mph). ?A Ford F-150 is 180 ft, about the same as my Honda. ?Virtually all the reported stopping distances are in this range. ?Car and driver say that braking distances have decreased since they started measuring in the 1970s, and now average about 170 ft from 70 mph. ?Of course, these distances were measured at a test facility with experienced drivers, choosing when to stop, and practicing hundreds of times stopping as soon as possible. ??(Anti-lock brakes have removed most of the skill aspect of driver braking in almost all cars, thankfully.)?

Aside from slower reaction times, average drivers will have trouble stopping in these distances due to not immediately pressing their brake pedals hard enough to turn on the anti-lock brakes or not being comfortable experiencing a high g-force.? They probably don't have a good sense of how long it takes to stop the car. They may have a coffee or a baby in the car they don't want to disturb.? Counteracting instincts while braking takes precious milliseconds and extends braking distance.

For cars trying to stop from higher speeds, the stopping time goes up, the kinetic energy to be channeled goes up, and thus, the frictional heat from the brakes is harder to dissipate.? Even sporty cars can have fading brakes when stopping from high speeds, ?causing much longer stopping distances than otherwise predicted.

Wet roads will double all these distances. ?Icy roads are much worse than that.

An excellent young driver, experienced in driving their Porshe, expecting to come to a complete stop on a dry road at any moment, who is paying 100% attention, can stop their car from 60 mph in about (44 + 100=)? 144 ft.

A more typical driver might be middle-aged, ?distracted by thinking about something else, driving an F-150, and not wanting to spill their coffee while braking. ?That would require more than ?(88+220=) 308 ft from 60 mph.

Necessary Following Distance

The tailgating car will only start to react once the car in front has already begun to stop.? So, the necessary stopping distance is determined by the difference between the tailgating car's total stopping distance and the car in front's braking distance.

The worst case is a tailgating car following a car with a shorter braking distance.??

So, a car with a 308 ft total stopping distance following a sports car with a braking distance of 100 ft would need to follow no closer than (308-100=) 208 feet.

Another critical assumption here is that the car in front does not hit anything once it begins to apply its brakes. ??If the car in front hits a stopped vehicle (perhaps because they were following too closely or not paying enough attention, as part of a chain-reaction accident), the tailgater could need the entire 308 ft to stop.

If you need to stop quickly but have a tailgater yourself, you obviously can't stop sooner than they can without being hit from the rear. Your own minimum safe following distance is that of the tailgater behind you, including that driver's reaction time and that car's braking distance. That's my main worry about having a tailgater. If you have ever had to modulate your braking while gauging the distance to the car in front of you as well as the distance and deceleration of the car in your rear-view mirror, you will have accomplished an amazing feat, if you don't get end up being hit or squashed between them

Futility

In my region, if the speed limit is 55 mph, a reckless driving offense is driving at 70 mph or more. ?That is a Class 2 misdemeanor punishable by up to 60 days in jail, a fine of up to $1,000, and suspension of your driver's license. ?I will assume that a tailgater will not drive faster than that to avoid such a huge penalty.

I drive 5 mph over the speed limit most of the time to avoid being passed by literally every vehicle on the road, which is dangerous. ?So, if the limit is 55 mph, I will go 60 mph.? My extra speed does not deter tailgaters.

75% of all trips in the US are between 11 and 15 miles. ?Let's assume the driver tailgating me is going on a 12-mile trip.?? At 70 miles per hour, that trip will take 10.28 minutes. ?At 60 mph, that trip will take 12 minutes. ?Therefore, the delay for my average tailgater on their 12-mile trip is 1 minute,? 43 seconds.

I wish they would compare this delay to a one-month recovery period or one month involved with insurance, the car repair shops, police, court, and lawyers. One month is 25,000 times that of the tailgater's delay.

That is IF the tailgater is able to get me to go faster, which will probably not happen.? ?What might happen is that I will pull over or turn somewhere during their?12 minute drive.? What also might happen is that it is not practical for me to speed up or get out of their way, and then something is suddenly in front of me, and then I have to brake hard.

What to Do?

First, always try to extend your following distance by observing the vehicles in front of the car immediately in front of you. ?If they slow, you slow.

I learned the "2-second rule" from my driving teachers: to follow the car in front so that we pass the same fixed spot 2 seconds apart. ?At 60 mph, that is 176 ft, which might be adequate in excellent circumstances.

However, the rule fails at higher speeds. ?The stopping distance grows at the square of the speed, and the two-second rule grows linearly with speed. ?At 80 mph, 2 seconds of following distance is only 235 ft, whereas a car going 80 mph will have a total stopping distance of 422 ft (a reaction distance of 117 ft plus another 305 ft, according to AASHTO).? And that assumes no brake fade and a dry road.

As mentioned above, if someone is tailgating you, you will need at least the tailgater's stopping distance in front of you. Since you don't know anything about them, your safe following distance at 60 mph might be 350 feet or more. Slowing down to correct your own following distance will not be at all well-received by your tailgater.

Knowing the danger, the best thing to do when being tailgated is to move out of the way. ?That is not always possible, for example on a single-lane road.?? Accelerating while the tailgater's distance remains constant will only make things worse. ?The theoretical answer is to simply remain at your current speed and look for an opportunity to move out of the way. ?

There is a significant danger that cars in our region will have to stop suddenly. ?In our area, we have deer that jump out of nowhere into the road, cars in bad repair, trees down, etc. ???Nevertheless, ?I routinely see five cars going 70 mph in a 60 mph limit zone, each following less than 40 feet apart.?

Slowing very gradually to the speed limit works for me about half the time.??When I have to move into the faster lane to turn, I often acquire a tailgater.? They will back off when I turn on my turn signal about 100% of the time, so I turn it on very early.

Tapping my brakes lightly to remind my tailgator works about once in 50 times. Using my windshield washer works about one in 5 times. ?A defensive driving instructor in The Netherlands suggested the washer trick or moving over just enough to kick up pebbles on the side of the road with your tire and have them bounce into the tailgating car. ??These techniques have a non-zero chance of pushing a tailgater into a psychotic episode, so they may do something even more dangerous. ?

Tailgating Simulator

I created a tailgating simulator game to hopefully improve the lives of a few people who might not have acquired safe following-distance discipline. ?In the game, you are in a car that can stop at the same distance as the car in front of you. ?That car will stop and accelerate at random times.?? Challenge your family tailgater; you may improve their instincts about following distance. ?See who can drive 10,000 feet in the shortest time? ?What is the best strategy for minimum fuel usage? ?Is a constant speed better?

I tuned my simulator using the published braking distance of a Porche 911 for both cars. The player's reaction time is incorporated in the time it takes them to press the 'brake' in the game.

You can use the brake and accelerator with mouse and touchscreen, or use the up arrow to accelerate and the spacebar to brake.

Here is the html5 version , which should work in most modern browsers.

Here is the Windows version .

Finally, I am sharing the entire project so you might learn something about making simulators in Godot and possibly improve on my effort.? Godot works on MacOS and Linux also. You can make a phone app too, if you have the developer kit.

Here are all of the project files in a zip file.?? Like all of my recent work, I wrote the simulator in Godot Engine . ?You can download the Godot Engine for free (use the LTS 3.5.3 version ). ?You can import this project by extracting my zip file in an empty folder.? ??Try it! ??I have commented on the code (see Main.gd ). ?Let me know if you have any questions about anything.

Burney Waring is an almost-completely retired global consultant engineer, and Director of Retirement Testing at the Waring Retirement Laboratory.

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