About the data
The majority of the data used comes from the US government. The Federal Highway Administration (FHWA) compiles an annual database stuffed with more statistics than a baseball archive.
Planning Time Index (PTI): This accounts for fluctuations in traffic. The higher the number, the less certain you are on any given day whether you’re going to be stuck all morning bumper-to-bumper, or show up stupid-early to work.
Travel Time Index (TTI): How slow traffic gets. The higher the number, the slower the traffic tends to get, compared to when the road is clear.
Daily Congested Hours: The total number of hours, per day, that traffic is significantly slowed
Thrillist Congestion Index (TCI): To figure out the total congestion index, we divided the total hours of daily congestion by the TTI, then multiplied that figure by the PTI, to give a true indication of how much time the traffic really does kill out of an average day.
Roughness (not shown): The International Roughness Index (yes, this actually exists) looks at road roughness by daily miles traveled. We weighted roads by how many miles they're driven each day, to account for real-world misery.
Death Rate (not shown): We then took the number of miles and multiplied them by 1/365th of the total number of annual fatalities for each area, to find how many people die each day for every mile. Hint: it's a decimal with a lot of zeroes after it.
Total Horribleness Rating: TCI x the weighted roughness x the deaths per mile = the worst part of your day, probably.
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Aaron Miller is the Cars editor for Thrillist, and can be found on Twitter. He's incredibly thankful he doesn't have to deal with any of these traffic nightmares on a daily basis.