BMS night race not full of cautions like it used to be

Is Bristol Motor Speedway really nastier at night? Did the change from an asphalt surface to a concrete one significantly increase cautions? And how much has the Chase affected the way drivers approach the August race? Perhaps it's time to try and separate the mythology from the reality. And in some cases, there are some surprising results.

From 1978 until 2003, the average number of cautions for both the day race in the spring and the night race in the summer were almost equal. There were a total of four more cautions and 115 more caution-flag laps run in the 26 night races. But since the Chase format was instituted in 2004, there have been significantly fewer night-time cautions.

There are multiple factors that may explain the change. The newer concrete surface has allowed for easier passing and cleaner racing in both the spring and summer races. And it could very well be the result of drivers -- those fighting for a Chase berth and the rest of the field -- being somewhat more conservative with the Richmond cut-off looming in the near future.

Beginning with the track's first night race in 1978, Bristol's contemporary history can be divided into five significant eras. For the first 14 seasons, the track was asphalt. In 1992, it was resurfaced in concrete. In 1997, the field sizes were dramatically increased. In 2004, the Chase format was introduced. And in 2007, the track was resurfaced again.

There were more caution laps run during night races in the first era, but more cautions thrown during the day -- including a combined total of 39 in Rusty Wallace's 1989 and 1991 wins. And contrary to the myth, the addition of a concrete racing surface in 1992 actually caused a temporary drop in yellows for the next five seasons, particularly in the spring race. While the five-year stretch beginning in 1987 resulted in an average of 15 caution flags per daytime race, the five-year period following the switch to concrete averaged just 9.8 yellows.

If there's a significant explanation for the huge increase in cautions in the latter stages of the 1990s, one only needs to look at the size of the fields. Until 1993, the average Bristol starting grid contained between 30 and 32 cars. By 1996, an average of 38 cars resulted in a total of 13 cautions in both events. The next season, NASCAR instituted the 43-car fields, and Bristol cautions rose significantly.

In the next seven seasons, there were fewer than 10 cautions only once, and there were a total of 37 cautions in 2003 alone. And the larger fields, coupled with the one-groove racing surface, combined to give Bristol's night race its slam-bang reputation. The Dale Earnhardt-Terry Labonte duels during that time only cemented that opinion in the minds of the fans, and the statistics bear that out. For five consecutive seasons starting in 1999, the night race averaged just less than three more cautions than the daytime affair.

But that trend reversed itself with the advent of the Chase format. Since 2004, there has been an average of 12.8 cautions in the spring, compared to 10.4 in the summer, and 190 more caution laps run during the day as opposed to the night races.

However, the new surface completed between the 2007 races -- and the addition of NASCAR's current chassis design -- has changed the dynamics again. Not only are there fewer cautions, but there is less of a statistical difference between the day and night races. There have been 19 cautions for 126 laps in the two spring races since the resurfacing, while the night races have accounted for 17 yellows and 117 caution laps.

So will Bristol's mean streak return? Perhaps as the concrete surface wears and teams learn more about making the cars handle Bristol's high banks, the average number of cautions may begin to increase again. But it's difficult to imagine getting back to the point where running 20 percent of the laps under caution at Bristol is the rule rather than the exception, particularly when so much is at stake at this point in the season.

The opinions expressed are solely those of the writer.