The 5 mph boost in the speed limit affects I-68 in western Maryland, but the State Highway Administration will study other interstates as well. (Robert Thomson/The Washington Post)

The Maryland General Assembly passed a law this year that raised the top highway speed to 70 mph, and now the State Highway Administration is boosting the limit on Interstate 68 in the more rural western part of the state.

That’s a 5 mph increase for I-68, which branches from I-70 near Hancock in Washington County and goes 80 miles to the West Virginia border. The increase, which will be posted on the highway Thursday, follows a review of highway conditions by SHA engineers.

Average daily traffic on I-68 ranges from 12,232 near Route 219 to 46,562 in Cumberland. On a hilly, seven-mile segment between LaVale and Cumberland, the current range of 40 to 65 mph will remain in place, the SHA said.

“We set speed limits based on roadway design and driver behavior,” State Highway Administrator Gregory Johnson said in a statement. “Increasing the speed limit can enhance safety by reducing aggressive driving and the variance in motorists’ speeds.”

The idea that raising speed limits could reduce aggressive driving is interesting. My own experience on Maryland roadways is that aggressive driving has nothing to do with the speed limit. Also interesting is the idea that the rest of us need to go faster to reduce the difference in speed between our travels and those of aggressive drivers.

In 2013, a study of driving behavior by the National Highway Traffic Safety Administration found that nearly half the drivers surveyed believed speeding was a problem on U.S. roads, while one in five said, “I try to get where I am going as fast as I can.”

Nationwide, crashes involving speeding accounted for nearly a third of traffic fatalities, taking close to 10,000 lives a year, the traffic safety administration said.

More than a quarter of drivers surveyed said “speeding is something I do without thinking” and “I enjoy the feeling of driving fast.” The survey also found that 16 percent felt that “driving over the speed limit is not dangerous for skilled drivers.”

Other surveys have noted that most drivers consider themselves above average.

But SHA will study other 65 mph highways for potential boosts to 70. The studies involve looking at crash data, traffic volume, concentration of truck traffic, actual average speeds and roadway conditions such as lane width, presence and width of shoulders, hills/grades, alignments and curves, the SHA said.

On I-68, highway crews will place overlays with “70” mph onto the black and white speed limit signs starting Thursday, which is the date the new law takes effect.