The truth about our driving

There is a good chance your blood pressure went up this weekend as you traveled on our highways to enjoy a Thanksgiving feast with family and friends.

There is the driver who cut in front of you, the one with the fast horn, the driver talking on a cell phone and not paying attention to the road. There is the driver who slowed to gawk at an accident.

I'm sure you can add your own grievances to this list.

I recently read Tom Vanderbilt's terrific new book "Traffic," an accessible look at what traffic studies tell us about how we drive.

As you might expect, we are our own worst enemy. We spend too much time on the cell phone, eating, drinking lattes, and applying lipstick. We drive too often when we are fatigued. And we all think we are above-average drivers.

Vanderbilt tackles one of the great traffic debates: When a sign says to merge, should you immediately go into the merge lane or should you continue down the road and merge at the last minute?

I am an early merger. But Vanderbilt says studies show I am wrong.

He argues that traffic flows more smoothly if both lanes are used to full capacity as long as possible before merging. Late merges improved traffic flow by 15 percent.

"Merging late, that purported symbol of individual greed, actually makes things better for everyone," Vanderbilt writes.

Then there is rubbernecking. When people see an accident, they slow down, delaying traffic even more. The gawking and slowed traffic lead to even more accidents.

Traffic congestion has a lot to do with our suburban lifestyle. Studies show there is now more traffic on the road at 1 p.m. Saturday than at rush hour. Drivers may stop at a Harris Teeter for one item, a Costco for another and a Trader Joe's for a third.

Most children no longer walk or ride bikes to school but are driven. And think about all the trips to soccer or dance practices.

On Black Friday, you might have found it hard to find a parking space at your local mall. But does it make sense to build a parking lot that will be below capacity for 364 days per year so that every shopper can find a space the day after Thanksgiving?

Here are some other interesting observations Vanderbilt makes:

* Men are more likely than women to be in a fatal accident. They are more likely to drink, drive aggressively and not wear a seat belt. They are also more likely to drive motorcycles. But women are more likely to be involved in nonfatal accidents.

* Surprisingly, one type of worker most likely to get into crashes is physicians. Doctors drive a lot in urban areas, are often on cell phones dispensing advice and often drive tired.

* Traffic in the next lane is probably not moving faster than your lane. It just seems so. Traffic is like an accordion. Each lane opens up at a different speed. Studies have shown that motorists spent 80 to 90 percent of their time looking ahead, which of course means sideways glances at the next lane. We spend only 6 percent of the time looking at the rear-view mirror. So we are more likely to see cars pass us than notice when we pass cars.

* The most dangerous roads are rural, non-interstate roads, where a car often runs off the side of the road. The cause may be poorly marked roads, high speed, fatigue, falling asleep or alcohol. A particularly dangerous time to be on the road -- any road -- is after midnight on Friday or Saturday, because of drinking.

As you return home today, let's be careful out there.