Can NASCAR Stop Secondary Accidents?

January is named after the Roman God Janus, who is the god of beginning, gates, transitions, time, doorways, passages and endings.  How’s that for a job description?

Janus is usually portrayed as having two faces: one looks forward and one looks backward. So I thought January might be a good time to look forward to things that might happen in the New Year.

The Preventable Accident

A secondary accident is an accident that happens as a result of another accident. In NASCAR, I’ll use the term to describe any accident that happens as the result of a yellow flag coming out.  You’ve seen it before: a car spins and a couple cars behind it end up crashing because they couldn’t avoid the first car or maybe even each other.

It’s not a NASCAR-specific problem. Every racing series has it. Not only is it a problem on track, it’s a problem on our roads. You’ve all seen the rubbernecker who is watching the accident cleanup on the side of the road and plows into the car in front of him. The term ‘secondary’ makes it seem like these are less-serious accidents, but people lose their lives in secondary accidents.

In 2002, Eric Martin was killed in an ARCA practice at Charlotte Motor Speedway. He crashed into a wall, but radioed his team that he was all right. Then his car was hit by another car still at high speed and killed.

Secondary accidents are one reason NASCAR is so strict about driver staying in their cars after a crash.

What Causes Secondary Accidents?

The primary cause used to be racing back to the caution. The implementation of the ‘Beneficiary’ rule (aka Lucky Dog) in 2003 has greatly decreased secondary accident

Throwing the caution too late can cause secondary accidents. These are situations in which the competitors have time and space to slow down, but don’t because they don’t know there’s a problem until they’re right upon it. In last year’s March XFINITY race in Las Vegas, Cody Ware spun. He came to a stop and could have continued; however, by the time the caution came out, Darrell Wallace tried to stop quickly and spun. He caught Justin Marks and they crashed into Ware.

It’s really easy to blame officials, but this is a value judgement and you couldn’t pay me enough to be the one making that decision. This is a place where technology really can’t offer any solutions.

The other main cause of secondary accidents is when the caution comes out and the driver can’t (or doesn’t) stop in time.  Sometimes you’re just too close and you’ve got no options. You don’t hit the brakes, you hit the guy in front. You hit the brakes, the guy behind you hits you.

But we’ve all see situations in which we’ve watched the replay, scratched our heads and wondered: Didn’t he know there was a caution? Didn’t his spotter tell him?

And that is how most drivers in NASCAR learn about cautions. They may catch a flag waving or lights coming on, but most drivers are so focused on their immediate environment that they don’t know there’s a caution until they spotter tells them.bspeed_2017_01_secondaryaccidents_pathtodriver


Does the Spotter Really Make a Difference?

At NASCAR speeds, even tenths of a second make a huge difference. Look how far the car travels at difference speed in a second.


At 200 mph, the car travels almost a football field a second. So even shaving a little bit off the time it takes for the driver to stop or take evasive action is going to make a difference. At 200 mph, in the first tenth of a second, a car has gone just about 10 yards. It’s not as big a deal at slower speeds, but slower speeds usually happen at smaller tracks, where there is less room to take evasive action.

So you might think having more than one way for the driver to know a caution has come out is good, right? Not necessarily.

One driver might see the flag come out and slow down, while the driver behind him might not even have realized there’s a caution yet. In series that rely on corner workers, it’s also possible that the flags fly at different times on different parts of the track.

Can We Cut the Middleman?

Spotters are critical to NASCAR due to the speeds and the limited visibility the drivers have. But many series don’t have spotters (or haven’t until more recently.) It’s worth looking at how they handle cautions.

Most rely on one of two in-car warning systems that use either light or sound to tell the driver directly when a caution has been called.

Seeing Red. Or Yellow.

The basic idea is that a light (usually amber) is mounted in the car’s cockpit. The light responds to a radio-frequency signal actuated by race control as they throw the caution. Every car on track is notified at the same time, and immediately.

Race Safe, an example of this type of system, was developed by Richard Martell in the mid-1980’s. You can see in the photo below the antenna for receiving the signal and the light, which is mounted on the dash somewhere the driver can’t help but see it.


You see the one amber light there, but the original patent envisioned something more complicated.


Figures 4 and 5 (from the patent) show the transmission device that would be used by race control to send the signals. Figure 6 shows a more complex configuration. There are two sets of lights (each set having a red, yellow and green), which could be used to communicate different situations (say red flag vs. yellow flag).  The signal is encoded when sent and decoded by the receiver, so there isn’t the chance that a stray signal could set off a receiver.

The Race Safe system has been mandatory in ARCA racing since 2003. Indy Car has also used this system.

Just a month ago at PRI (The Performance Racing Industry Trade Show), USAC announced their own proprietary system. It is similar to  Race Safe in that it has an in-car dashboard indicator connected directly to Race Control. The indicator turns yellow if there is either a red or a yellow flag

But they also have green three lights on the backs of the roll cages that are integrated into the system. During green-flag racing, the lights show running position. The first-place car has one green light, the second place car has two and the third-place car three.

But as soon as there is a yellow or red flag, the three lights on the backs of ALL cars flash rapidly, signaling the drivers that there is a full-course yellow. So even if you’re looking up at the bumper of the car right in front of you, and not at your dash, you’re going to know right away that there’s a flag you need to react to.

I like this solution – some series have brake lights on the cars as a way of warning the driver behind, but I suspect that might cause more trouble that good in NASCAR. This gives you the same visibility, but it’s not under the driver’s control.

A Sound System for the Race Car

These systems work on the same principle as the light-based in-car warning systems, expect the driver is notified by sound instead of light.

The Audible Flagging System was developed in the late 80s by David Skeen (and patented in 1998). When a caution is called, a very specific, tone is transmitted to the driver. The system is designed to interface with a driver’s normal radio system. The tone comes through the driver’s earpiece to ensure he or she can hear over the car noise.

As with the light-based systems, the original patent envisioned the option of using different tones to communicate different situations:  red vs. yellow or full vs. partial course cautions. The driver can hit a reset switch to shut the tone off.

The patent suggests a possible street use for the device: To alert drivers to the presence of emergency vehicles in their proximity: The emergency vehicle could transmit a signal and any car with a receiver in the area would get an alert. This is even more important because cars are more noise-tight than ever – plus some of us have a bad habit of blasting music at top volume and sirens don’t always cut through our tunes.

This system is going to be used by the Pirelli World Challenge Series next year.

Light vs. Sound?

Both systems are secure: they use radio frequencies to send the signals that turn on the light or the sound. The signal is encoded by the transmitter and decoded by the receiver, which eliminates the possibility that the signals could be accidentally activated.

The timing of both systems is the same: they give pretty much instantaneous notification to the driver. All drivers are notified at the same time. None of the systems requires involving the spotters and none of them interfere with the communications between the driver and his or her team.

The people who like the sound approach suggest that there are situations in which the light might not be seen: bright daylight, the glare of the track lights, etc. LED technology has made that mostly a moot point.

The more persuasive argument for sound over light is that there are many things competing for the driver’s visual attention. The RaceTrac system tries to address that by assuming that you’re probably going to see flashing lights a few feet in front of you.

The people who like the lights note that the sound approach won’t work with hearing-impaired drivers (and race car drivers often have hearing issues); however, Audible Flagging Systems has a vibrate option that actually stimulates your sense of touch rather than sound.

You Hear Faster than You See

Here’s something surprising I learned while researching this topic: Human beings hear faster than we see.

We react faster to a sound than we do a light. We measure this by reaction time: the time between when you see a stimulus (a light or a sound) and when you react to it.

Here are two websites: The first tests your visual reaction time and the second your audio reaction time.

Unless you have impairment in your vision or hearing (or you are a superhero), your reaction time for sound will be smaller than your reaction time for sight.

In fact, a study in the Internal Journal of Basic Medical Research (5(2), 123-127 (2015)) did a very careful measurement of reaction times in medical students (whom we hope have really good reaction times).

The average reaction time for sound was about 20 milliseconds  (2 hundredths of a second) faster than it was for sight.


Why? It has to do with the process of converting photons to bioelectric signals versus converting pressure wave (i.e. sound) to bioelectric signals. It takes about six steps to register a visual stimulus.

  • A photon (light) hits a molecule called retinal, which is in a protein called rhodopsin
  • The retinal makes the rhodopsin changes shape
  • The shape change kicks out a protein called transducin
  • The transducin meets up with an enzyme called PDE (Phosphodiesterase)
  • When PDE gets transducin, it starts using up a chemical called cGMP
  • cGMP controls the sodium ion channel, which is what produces the bioelectric signal.

These steps all take time. There is no way for a visual reaction time to fall below 150 milliseconds.

Hearing takes one step: The pressure waves make the hair cells in your ears wiggle and that makes ion channels open and close. Auditory reaction times can be as fast as 70 ms.

A Little Lemma

The above-referenced paper also looked at gender differences in reaction times. They found that men had uniformly faster reaction times than women to both sight and sound.

The time it takes to contract a muscle is the same for men and women; however, the motor responses (the time it takes to start the contraction of the muscle) is stronger for men than women.


Interestingly, the gap between male and female reaction times has always been there. But it’s getting smaller. In fact, the researchers broke out the data into people who exercised regularly and those who didn’t. If you limit yourselves to the regular exercisers, there is no difference in reaction times for men and woman.

The authors suggest that women’s reaction times are catching up with men’s because “More women are participating in driving and fast-action sports”.

For the purposes of this topic, that twenty milliseconds isn’t going to make a huge difference in choosing between a light and a sound.


Spotters — even the best — are an unnecessary link when we’re talking about drivers knowing there’s a caution flag out. Even more critical, however, is that drivers learn about cautions at different times, which is a recipe for secondary crashes.

Arguments can be made for a system based on light or a system based on sound; but based on anecdotal data from other series, either type of in-car warning system would likely decrease the number of severity of secondary accidents, thus keeping drivers safe and decreasing costs by decreasing damage to cars.

BUT: Even with one of the systems, race car drivers are human being. They make mistakes. There is no technology that can eliminate human error from motorsports entirely. So we’ll never eliminate secondary accidents, but we could do a lot to minimize the number and severity of them.

1 Comment

  1. This isn’t real hard to solve. The problem is the NASCAR has a tech phobia. Anything digital or wireless makes the folks in Daytona crazy.

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