How Often Are There Cautions in the Last 10 Laps of a Race?

Every week, someone calls into SiriusXM NASCAR radio and suggests that NASCAR manufactures cautions in the last 10 laps of a race. So I got to wondering: How often are there cautions in the last 10 laps of a race? And why?

The Data Set

I’m using all races between 1970 and 2021-07 (the Bristol Dirt Race). That’s 1404 races.

However, I’m throwing out all the races that didn’t go the scheduled distance because of weather or darkness. Many of those have a caution in the last lap because the race couldn’t continue. That’s all on Mother Nature.

That leaves us with 1354 races that went the scheduled distance (or longer). I plot below the number of races by decade, breaking out how many of those are weather-shortened or overtime.

A breakdown of NASCAR races by decade 1970-2020 that shows full-length, shortened and overtime races.
Shortened races are those that didn’t go to the full length, usually due to weather, but sometimes to darkness.

It’s pretty amazing, really, that in 42 years, there have only been 50 races that didn’t go at least the scheduled distance. That’s only 3.5% of races.

Over the same time range, 132 races have gone into overtime. And remember that overtime didn’t exist until mid-2004.

When Was the Last Caution in Each Race?

I looked through these races and tallied up the lap at which the last caution of the race started. Obviously, in races that went into overtime, the last caution was within the last 10 laps of the race. But what about the rest of them?

Well, here’s a histogram showing how many cautions happened within each 10 laps of race end.

The horizontal axis shows the number of laps before the end of the race and the vertical axis shows how many cautions happened within that frame. The leftmost bar is how many times the last caution in a race came within the last 10 laps.

Out of 1354 races, 384 (28.3%) had a caution within the last 10 laps of the race. Between laps 11-20, the number falls to 180 races (or 13.3%) — almost half the number as in the last 10 laps.

So a little more than one race in four has a caution within the last 10 laps.

If we go a little further out, 53.5% of the races have a caution within the last 30 laps. So now the questions are: 1) Where are all these last-ten-lap cautions happening? and 2) what’s causing them?

Are Last-10-Lap Cautions More Likely at Some Tracks?

Yes. They most certainly are.

A column chart showing the percentage of races that had a caution in the last 10 laps by track

You can see from the graph above that the longest tracks are much more likely to have a caution within the last 10 laps, which makes sense because there’s just that much more space in which to instigate chaos. The last 10 laps at Talladega are almost 26 miles, whereas the last 10 laps at Martinsville are a little more than 5 miles.

But Phoenix and Martinsville are surprisingly high up in the list for shorter tracks.

What Causes Those Cautions in the Last 10 Laps?

Let’s look at the reasons for those cautions, and limit ourselves to the last 10 laps. Here’s a pie chart breaking down the reasons for those 254 cautions.

A pie chart showing the causes of cautions in the last 10 laps of races

Interestingly, 66.1% of the last-lap cautions are due to accidents and 14.8% are due to spins. Add those together, and 80.9% of all last-10-lap cautions are caused by drivers. That sort of jibes with what we know about drivers getting anxious toward the end of the race.

Debris cautions only make up 7.1% of last-cautions within the last 10 laps. So the idea that NASCAR is manufacturing cautions at the very end of the race isn’t supported by the data.

What About the Last 30 Laps?

I did those calculations, too. The percentage of cautions in the last 30 laps due to accidents and spins is only 75% and the percentage of debris cautions rises to 9.3 percent. But debris cautions are still only about 1 out of 10, while accidents and spins are 3 out of 4.

Debris and Accident/Spin Data

One of the issues with debris cautions is that they are subjective. Drivers and fans tend to complain about them when the caution impacts their team negatively. Here’s a plot of the average debris cautions per race from 1980-2020.

A column chart showing the average number of debris cautions per race by year from 1980-2020

You can see a couple things here. One is the sharp dropoff in 2017, when NASCAR instituted the damaged vehicle policy. As you can see from the graph below, there wasn’t a huge decrease in the rates of accidents or spins, yet the debris cautions dropped off anyway.

A column chart showing the average number cautions due to accidents and spins per race by year from 1980-2020

Another factor I want to mention is NASCAR’s increased emphasis on safety in the years immediately following the string of deaths in 2000-2001. They were already starting to think about the Car of Tomorrow design, and one of the mandates was that it would be the safest racecar NASCAR ever built. NASCAR was also starting to install SAFER barriers and require HANS devices. They were hyper-sensitive to safety issues and happy to err on the side of calling a caution than taking a chance on a freak accident sending a piece of debris through someone’s window net.

Conclusion

While it is true that there are often cautions within the last 10 laps of a race, the majority of those cautions are caused by spins and accidents and not NASCAR-initiated debris cautions.

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