SAN DIEGO — If you’re reading this while driving, you’re guilty of breaking the fourth commandment of trucking: Driving while Distracted.

That’s right. Fourth.

Considering all the attention regulators have paid to drivers using cell phones and texting, there’s a good chance you thought that driving while distracted was no-no numero-uno, right?

Here’s the news: A study released today by a San-Diego based company that manufactures driver-monitoring systems shows that when it comes to big-truck crashes, distracted driving isn’t really the biggie it’s made out to be.

Indeed, according to the study done by DriveCam Inc., the most serious perilous driving activity is following too closely. About 27 percent of accidents were caused because of tailgating.

Number two (26%) is failing to look far enough down the road and number three (12% of accidents) derive from they refer to as traffic violations; i.e., rolling through stop signs, bad lane changes, speeding, etc.

Distracted driving (texting and handheld cell calls) was fourth and failing to keep an escape-route open is fifth.

The data comes from DriveCam’s client database of more than 17 million driving events from two billion driving miles.

In another part of the same study, DriveCam found a significantly lower collision rate among trucks in energy services (0.8 %) compared with those operating in OTR (5.9 %) and local P&D work (5.8 %).