The number of traffic accidents on Interstate 295 between Falmouth and Gardiner jumped nearly 32 percent in 2015 compared with 2013, the last year before the speed limit was increased to 70 mph.

A Portland Press Herald review of state transportation data found there were 354 crashes on that stretch of I-295 in 2015, up from 269 in 2013. The figure for 2015 was roughly 25 percent higher than the average of 284 accidents on that segment of the highway from 2006-2013.

State traffic engineers met Wednesday to analyze a variety of data relating to the increase in crashes on I-295, including driver behavior, increased traffic volume, time of crashes and even fluctuations in gas prices. The Maine Department of Transportation plans to issue a long-term report on I-295 traffic.

“This effort is to identify short- and possibly long-term solutions to assist with traffic flow and keeping the interstate as safe and efficient as we possibly can,” said Ted Talbot, spokesman for the MDOT.

Wednesday’s meeting followed a rash of accidents in the past few months on the interstate north of Portland, including five crashes involving 11 vehicles during the northbound commute Monday evening.

“Traffic was totally snarled,” Maine State Trooper Michael Smith said at the time. “All it is is people following too closely.”

Smith said he and other troopers have noticed a significant uptick in traffic volume on the road.

“There is so much traffic out there now. People are following too closely and the roads just can’t handle that volume,” Smith said.

Talbot could not immediately provide data on traffic volumes on I-295, saying it would likely be available next week.

The department raised speeds on some sections of I-295 from 65 mph to 70 mph in June 2014, after the Legislature’s 2013 passage of a bill that gave the transportation commissioner the authority to raise speed limits on the interstate as high as 75 mph.

HIGHER SPEEDS, MORE FATALITIES

Proponents of higher speed limits argue that posted speeds should match those that drivers are already comfortable with. Many states, including Maine, determine limits based on the speed that 85 percent of drivers on a road are traveling at or below, among other considerations.

“A properly set speed limit will be within 3 miles per hour (±) of this observed speed,” the MDOT website says.

The rationale for raising the speed limit is that roads are safer when more drivers are traveling at similar speeds. However, national studies have consistently shown that higher speed limits lead to more fatalities and injuries, even on less congested roads.

A 2009 study in the American Journal of Public Health examined the 1995 repeal of the federal speed limit, which capped U.S. interstate speeds at 55 mph, and found that between 1995 and 2005, higher speeds contributed to a 3.2 percent increase in the number of road fatalities nationwide, or 12,545 additional deaths. The highest increases were found on rural interstates (9.1 percent) and urban interstates (4 percent). The study estimated that higher speeds resulted in 36,583 additional injuries during the decade it covered.

In 2015, researchers at Wayne State University looked at national speed limit data for rural interstates and found that states with 70 mph speed limits saw 22.2 percent more fatal crashes than those with 60 mph or 65 mph limits. States with speed limits of 75 mph or higher saw 51.5 percent to 124.7 percent more fatal accidents than those with lower limits.

CRASHES ON I-295 UP THIS YEAR

Timothy J. Gates, an author of the Wayne State study, said that when speed limits are raised to reflect existing driver habits, they ultimately encourage motorists to drive even faster.

“The impact on fatalities in crashes in general is all related to what ends up happening with vehicular travel speeds once you change that speed limit,” Gates said. “My best estimate right now is for every 5 miles per hour you raise the speed limit, you can expect travel speeds to increase by (another) 1-2 miles per hour.”

Those results are not restricted to highways. Researchers in the 2009 study found that higher speeds on interstates persisted even after drivers exited onto smaller roads.

In a 2002 survey conducted by the National Highway Traffic Safety Administration, 78 percent of drivers admitted to speeding on multi-lane interstates. Nearly three quarters or more of drivers said they also sped on two-lane roads, city, town or neighborhood streets, and non-interstate multi-lane roads. In a later study the NHTSA said speed was “one of the most significant contributors to crash severity and traffic fatalities.”

The number of fatalities on the stretch of I-295 north of Portland has not increased over the years. But since the MDOT raised the speed limit there to 70 mph, drivers have experienced more crashes than average in 22 of the 28 months through September 2016. Some months saw as much as a 91 percent jump in accidents compared with averages from the past 10 years.

This year, crashes on I-295 are on track to surpass the 2015 numbers, with 265 reported through the end of September, a 6 percent increase over the 250 during the same period in 2015 and 32 percent higher than the average of 201 accidents during the first nine months of the year from 2006-2013.

Increased speed may not be the only factor contributing to an increase in crashes. The Insurance Institute for Highway Safety, which conducts highway safety research, has found that economic activity in an area is a useful data point that speaks to several potential contributing factors, including driver behavior and traffic volume. In a study of the national economy from 1951 to 2014, the institute found that as the unemployment rate decreases, accident deaths increase.

“We see this over and over again, and part of it is the fact that there are more vehicles on the road and people are driving more, but it’s also that the riskier driving comes back after a recession,” said Russ Rader, senior vice president for communications. “That is, if people are feeling better about the economy they’re more likely to go to bars and spend money, more likely to go on long trips on unfamiliar roads. Those kinds of things lead to increases in crashes and deaths, and we’re seeing that nationwide.”