A three-year experiment will come to an end next month when the Maine Department of Transportation restores the speed limit to 65 miles per hour along a crash-prone stretch of Interstate 295.

The speed limit had been increased to 70 mph in 2014, after the Legislature passed a bill that gave the department the authority to increase speeds where conditions permit, in part to reduce the number of crashes.

But that’s not the way it worked out. Vehicle collisions increased 29 percent between June 2013, just before the speed limit increase, and last May.

The department is now moving in the other direction on the speed limit, probably making the road between Falmouth and Brunswick safer. The change may even save lives.

But on its own, it’s not enough. There are multiple reasons for the increase in collisions, and while the higher speed was no doubt a factor, it was not the only one.

During the same three-year period, traffic volume increased by 6.4 percent. The highway operates near capacity during peak commuting times, which is also when most of the collisions occur.

State troopers report that drivers are moving at high speeds close together, leaving little room for error. More vehicles in tight proximity have a predictable result – more crashes – at any speed.

And as a nation we are experiencing an epidemic of distracted driving, which has been blamed for an increase in traffic fatalities despite safety improvements to passenger cars. Ten years since the introduction of the first smartphones, we have not been able to come to terms with the extraordinary temptations that drivers face daily to turn their attention from the road. These other factors will not be as easy to fix as the speed limit.

Some will argue that additional lanes are needed to ease congestion, but that is just a short-term fix, and an expensive one at that.

Frequent and reliable mass transit, possibly commuter rail, would reduce traffic volumes, but it also would require a significant public investment and a change in behavior. Most Mainers don’t have experience with mass transit, and would take time to adapt.

Reducing distracted driving could be less expensive, but not any easier. While it’s no longer socially acceptable to get behind the wheel obviously impaired by alcohol, it is considered an innocent vice for a driver to glance at a smartphone to check email or even type a message. According to the U.S. Centers for Disease Control and Prevention, distracted driving kills eight people a day, with cellphones the primary source of inattention.

The Maine DOT is doing the right thing by reducing the speed limit on I-295. But there is still a lot of work to be done to make it and all of our highways as safe as they can be.