HARRISBURG — Pennsylvania motorists who gravitate toward the left lane may have to wait a bit longer to learn whether state policymakers consider it safe to increase interstate speed limits to 70 mph.

A Penn State study of crash and speed data in pilot areas where the higher speeds have been in place for about year found no significant overall increases in speeds for either cars or trucks, and the percentage of vehicles going faster than the posted limit actually deceased by about a third.

The higher speeds were authorized by a major transportation bill in 2013 that raised gasoline taxes and motorist fees to fund billions in infrastructure improvements.

Since then, the Pennsylvania Turnpike and the Pennsylvania Department of Transportation have been studying higher limits of 70 mph on a 97-mile stretch of the turnpike, on an 88-mile portion of Interstate 80 in the center of the state and on 16 miles of Interstate 380 in northeastern Pennsylvania.

“We picked these pilot areas after reviewing information, such as best practices, from other states and analyzing speed and traffic data,” said PennDOT spokesman Rich Kirkpatrick. “We wanted to analyze locations in different areas of the state to review stretches with varied traffic conditions.”

The highway department and turnpike commission will have to decide which portions of interstate where the top speed is now 65 mph might be good candidates for the 70 mph limit.

Kirkpatrick said lower speeds don’t necessarily equate to greater safety.

“An industry standard is to post speeds within 5 mph of what roughly 85 percent of the traffic is doing, or lower,” he said. “For example, we would not post a 30 mph speed limit on an interstate, because the difference between the limit and actual motorists’ speeds would be too great and actually reduce safety.”