After a dramatic increase in the number of crashes on Interstate 295 north of Portland, the Maine Department of Transportation on Monday lowered the speed limit back to 65 mph on a stretch of the highway from Falmouth to Topsham.

The 70 mph speed limit through Portland’s northern suburbs lasted nearly three years after it was raised May 27, 2014 between East Deering in Portland and the West Gardiner exit. In the 12 months that followed, the total number of crashes on that stretch of road increased 29 percent compared to the 12 months before the speed limit change took effect.

A Press Herald analysis of state crash data shows that the increase in crashes was much more dramatic on the sections of the freeway in Portland’s northern suburbs. The section of I-295 between Portland and Falmouth had a 63 percent increase in crashes. The stretch of the freeway from Yarmouth to downtown Freeport saw a 90 percent increase.

Not surprisingly, the number of crashes that involved injuries also increased after the speed limit increase took effect on these sections:

I-295 crashes, by section

The Portland and South Portland segments of the highway, where traffic volumes are heaviest, had no change in the number of crashes. This fact undermines MDOT’s claim that increasing traffic played a role in the surge of crashes, since traffic volumes have increased at least as much on these sections of the highway compared to the sections north of Portland.

Sorting the crash data by hour of the day illustrates that the increase in crashes was most pronounced during the midday hours, between 10 a.m. and 4 p.m.

I-295 crashes, by time of day

The number of crashes on the high-speed section of the interstate actually decreased during the late night periods and afternoon rush hours in the 12 months after the higher speed limit took effect.

Check out all crashes

The map below plots the locations and severity of all 2,749 crashes reported on I-295 over the 5-year period from 2010 to the end of 2015.

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