“There’s a phenomenon that sometimes occurs ... it just means that sometimes things go up for a couple of years and then they’ll go back down and you can’t understand why,” he said. “The question will be whether that trend stays up for multiple years or naturally goes back down.”

Fatality accidents decreased from four to two during the same 2012-2013 time period. Fatality accidents continued on a downward trend through last year, which saw just one fatal crash, the statistics show. But, there already have been six fatal crashes this year, half of those in May.

In all three of the May crashes, officials said the victims weren’t wearing seat belts.

Ullman said the serious accidents are consistent with national trends.

“National fatality trends have increased and look to be on the increase this year as well,” he said. “It’s a little bit disheartening. ... Without looking at the types of crashes it’s hard to speculate why.”

He said there has been a concerted effort since 2012 at a national level to bring fatality accidents down across the country, and it was a movement TxDOT embraced. He said the decrease in fatalities up to this year suggests that TxDOT’s efforts were being successful.