Gridlock Guy: Traffic stats flat absent of common sense

Stories and headlines often precede most major holidays about the best and worst times to travel. The large banks of data that firms like INRIX, Waze, and Google collect can be extremely useful in tracking past behavior and informing our present and future. Motorists plan around trends and have more data than ever to do so. But data is only useful if applied within context.

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The recent July 4th weekend came with its own headlines about traffic trends. AAA anticipated nearly two million more motorists would hit the road, and more than 40 million would drive. But within their holiday news release came this surprising revelation from travel data firm INRIX: the worst time to travel for the July 4th weekend was supposed to be July 5th from 5-7 p.m. This seemed very much counterintuitive.

This past July 4th was a Thursday, meaning traffic data was predicting that the busiest time to travel would be a Friday afternoon. Friday afternoon traffic before holidays is generally awful, with PM rush hours that start and peak very early, but that usually ends early.

Recent July 4th holidays have happened midweek, so many people not taking most or all of those weeks off would have to return on a July 5th. This trend is what informed traffic data to spell July 5th as a busy travel holiday. Data is a prism and all sides need examining to make the proper judgment.

One beam of refraction seemingly left unseen in this data dump is the day of the week the holiday fell upon and how that would influence driver decision making differently. With Independence Day at the end of the week, that meant people were much more likely to take a four- or five-day weekend and extend the holiday. In fact, PM drive on July 3rd was more like a pre-holiday Friday. The roads got busier around lunch and stayed thick into the evening. Let the weekend begin!

But if the weekend was on, why would it end on a Friday afternoon? This report brought news organizations (including the three for which I work) to run the headline suggesting that the worst traffic would be a time when people would be dead-center in the middle of their holiday. The WSB Traffic Team was fully staffed for Friday afternoon, just in case.

Here’s what happened: The Friday PM commute wasn’t heavier than normal. It was actually far lighter than normal, just as the morning commutes generally were that week. There was no PM drive. The ride on I-75 in Henry County wasn’t even that slow. The only real delays anywhere in Atlanta were because of wrecks. The robots guessed wrong.

In fact, the worst travel period of the July 4th holiday was what we suspected it to be. Saturday and especially Sunday afternoons saw droves of people marching up and down I-75 in the McDonough-Stockbridge area. People leaving town, returning, and passing through stopped it up. And this caught those going merely by headlines and trends off guard.

So the lesson here is that we should always question headlines, studies, stories, and data and hold them up against common sense. If any headline causes you to raise your eyebrows, read the whole story. If it still doesn’t sit right, consider what factors the story or study may have missed. Frankly, more media outlets (including my own) would do themselves better to question studies before writing them into stories and presenting them as facts.

Fortunately on News 95.5/AM750 WSB, Atlanta’s Morning News host Scott Slade and I talked on the air briefly about if we thought roads would be that bad in that 5-7 p.m. window on July 5th. We each expressed our skepticism and said why we did not.

The other lesson learned in this missed prediction is again that raw data is nothing without the proper analysis and filter of common sense. Sure, our sense can be wrong and data has proven that. But traffic statistics have often times come presented as sheer fact and have conflicted each other. Several years ago, there were two studies just months apart that ranked how bad Atlanta’s traffic was. One said Atlanta had one of the top 10 worst commutes in the world. The other said that Atlanta’s rush hours were 12th-worst in the U.S. While those studies are fun to read and brag or moan about, they make little difference on our commutes themselves. Their results were so far apart that the studies just look silly.

There are all sorts of ways to measure bad traffic and they can each produce different results. So just as we should with any bit of information, we need to hold them against what we know and expect before accepting them as fact. A little bit more critical thinking around the July 5th commuting data might have made for some different, more accurate headlines and conclusions.

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Doug Turnbull, the PM drive Skycopter anchor for Triple Team Traffic on News 95-5 FM and AM-750 WSB, is the Gridlock Guy. He also writes a traffic blog and hosts a podcast with Smilin’ Mark McKay on wsbradio.com. Contact him at Doug.Turnbull@coxinc.com.