It occurred to me this past weekend that to truly understand the changes in one’s life, one needs to have a constant to use as a baseline.

One of my constants is about 250 miles long — the drive between Dayton, Ohio, and Pittsburgh.

I first made that drive, mostly on Interstate 70, with most of my stuff in a 1968 Volvo 122S station wagon, in the fall of 1986, after I accepted a job as a feature writer for The Pittsburgh Press.

During the eight years I lived in a Mount Washington apartment and during the 30 years I’ve lived in my Mt. Lebanon house, I’ve made that drive back-and-forth countless times for holidays and birthdays, weddings and other reasons — my mom was dying, my dad had just died — countless times, in every kind of weather, almost always through construction and past many state troopers, at all hours. I’ve done it as fast as three hours and in several different vehicles.

But I know I’ve almost never done it sitting in the passenger seat, as I did this past weekend, while most of the way, in both directions, my 16½-year-old son drove.

On the way to Dayton, to celebrate a family member recuperating from major surgery and being declared cancer-free, I thought of the trips I’d made with my son as a newborn. Ever since, my wife and I never have failed to remark on the rest area on this side of Columbus where our son used to get his baby bottle and where, on one unforgettable occasion, had to be placed in the trunk of another old Volvo to have a total mustard yellow blowout of a diaper changed.

This past weekend, as we passed that rest area, my son, proud holder of his learner’s permit, was at the wheel, with me riding shotgun.

He will tell you what I was riding was his ass. I won’t dispute that. But save for not always honoring the “limit” in “speed limit” and a few other minor things, he drove very safely and well. He probably could have driven the whole way, but the three hours he did were the longest he’s ever driven, and all of it was in below-freezing temps and some of it in falling snow. So after we stopped for gas, I took the stretch through and past downtown Columbus and Dayton proper.

But having thus driven all the hours required to take his driving test, he confidently drove us around Dayton all weekend to see our family members, including his grown cousins and brand-new baby second cousin, including in the dark after dinners out both nights, and the last morning to my alma mater, the University of Dayton, for a campus (!) visit.

And he was back at the wheel on the way home on Monday, even though it was by then evening rush hour and I was extra nervous about the interstate traffic and distracted drivers, stale greens and rutting deer, and watch that pothole and how are we on gas? …

He drove great.

I still couldn’t quite let go. So I let him drive as far as Cambridge, Ohio, where we stopped for fuel for the car and for Jesse and my wife, Anita, from Starbucks, and I took back the wheel for the last leg home.

“See how dark it is up ahead,” I said as I hurdled faster than the speed limit around curves and over hills.

He was riding shotgun but back to focusing on his phone.

For once, I didn’t mind that.

Interstate 70 has changed — there are more lanes here and there, more traffic, a LOT more semi trucks with nowhere to park at night, and the evidence of fracking is fresher than the strip mining that preceded it — but it’s still basically the same road, and I know it with my eyes closed. My life ahead, not so much.

Back home on Tuesday, after school, Jesse passed his driving test and got his junior license.

Tonight, after dinner, he drove himself to the high school for percussion rehearsal.

His mom took a photo of him backing out of the driveway and gave him a play list of songs about cars by everyone from Gary Numan to Kanye West to Tracy Chapman.

I gave him this dad classic: “Just because you have your driver’s license doesn’t mean you can drive whenever you want!”

(Actually …)

I’m sitting here, waiting for him to drive himself home. In the dark. In another hour and a half.

Time goes fast and time goes slow. I know how time goes.

But as I will keep telling Jesse, as a beginning driver especially, and if your dad still needs to catch up, there’s no reason to go too fast.

Bob, a feature writer and editor at the Pittsburgh Post-Gazette, is currently on strike and serving as interim editor of the Pittsburgh Union Progress. Contact him at bbatz@unionprogress.com.

Bob Batz Jr.

Bob, a feature writer and editor at the Pittsburgh Post-Gazette, is currently on strike and serving as interim editor of the Pittsburgh Union Progress. Contact him at bbatz@unionprogress.com.