Next time you're in a traffic jam, take note of when you finally start getting back up to a steady speed. It probably won't be immediately after you pass the fender bender. In another Kaggle study, researchers found that while a traffic jam certainly extends backwards, it also propagates forward. "Not nearly to the same extent," said Goldbloom, "but certainly a little bit."
What the researchers can't yet determine, though, is why this happens.