The Kansas Department of Transportation has released some notable numbers on the increase in fatal accidents on highways where the state raised the speed limit three years ago.

In mid 2011, the state raised the speed limit from 70 mph to 75 mph on 804 miles of highway, covering mostly rural stretches of Interstate 35, Interstate 70, U.S. Highway 69, Interstate 470 near Topeka and Interstate 135 north of Wichita. The thinking of state legislators was that the increased speed was safe and reasonable for the multi-lane highways.

It’s reasonable to think that a 5 mph increase in the speed limit wouldn’t have a significant impact on the safety of those roads, but since that time, fatal accidents have almost doubled. In the two years before the speed limit was raised, 48 people were killed in 38 accidents on the affected highways. In the two years after the switch, 74 people died in 59 wrecks. Injury accidents also were up by 13 percent during the same periods.

A spokesman for the Insurance Institute for Highway Safety said that the increase in fatality and injury accidents was consistent with what other states have experienced with higher speed limits, but Kansas officials aren’t so sure. To know whether the speed limit was the primary culprit, they said, they would need to look harder at other factors in the accidents, including whether the driver and passengers were wearing seat belts and whether the driver was intoxicated or was talking on a cell phone.

Other studies have indicated an increase in seat-belt use in the state, but, even with some new laws in force, inattentive driving linked to texting and talking on cell phones seems to be a rising problem. Many new laws also have been added to deal more harshly with drunken drivers, but it also would be interesting to know how large a factor that is in the new statistics.

Another factors is exactly how fast people actually are driving. The speed limit is only 5 mph higher but many drivers probably are driving 10 mph or 15 mph faster.

It’s hard to know what is making the difference in traffic fatalities on those highways, but the situation seems worth a second look. If it’s not the higher speed limit, what is it?