Don't Want To Be Late? Researchers Find Buffer Time Needed For LA Commuters

LOS ANGELES (CBSLA.com) — Drivers in Los Angeles not only bear the burden of painfully sluggish traffic, but it's the unpredictability of it all that can wreak havoc on your schedule.

You've probably fallen victim to this scenario: You use a traffic app to find the best possible route to work or to the airport, only to find that when you're on the road, the gridlock is so much worse than anticipated.

With a clenched jaw and a groan, you realize you're not going to make it on time, even with the extra time you allotted for traffic.

Oddly enough, at the same time on other days, it's smooth sailing.

So, how early do you need to leave in order to arrive on time?

According to a new study, the answer can be found in what traffic engineers call the Buffer Time Index, or BTI. It's the extra percentage you'll need to add to your typical commute time.

The study listed San Francisco as the most predictable metropolitan area in the nation, with a BTI of .41, which means you'd only have to add an extra 12 minutes to a 30-minute commute.

Los Angeles was one of the least-predictable cities listed in the study. The BTI was a whopping .85, which means for a 30-minute commute, you need to add on an extra 85 percent or 25 minutes to be confident you'll arrive on time.

Drivers here will tell you it doesn't take a scientific study to figure that one out.

"I find it comically unpredictable, frustrating, aggravating, all those wonderful things," driver Samantha Sedaka said.

But there are efforts to ease the congestion. Public transportation agencies are adding carpool lanes, there are freeway service patrol tow trucks roaming the roadways clearing stranded cars and there's a growing number of express toll lanes that let solo drivers pay based on the amount of gridlock they're allowed to avoid.

Still, nothing's changing the underlying problem in this city: There are too many drivers and just not enough asphalt, which means you'll always have an unpredictable commute.