THE ENGINEER STILL HAS NIGHTMARES.

Train crews generally survive collisions with motor vehicles or pedestrians.  Walking away is not the same thing as being able to put it behind them.

The dream that has visited Ford Dotson Jr. thousands of times always starts the same way.

It’s a crisp October morning. Beneath clear skies, leaves shimmer copper, gold and red.

It’s long before sunrise, and Dotson sets off from home. He’s happy anyway because there are no weekend shifts, no one bugging him to work holidays. He climbs into the cab of Metra’s Union Pacific Northwest Line train No. 624 heading to Chicago from Crystal Lake. At the end of the run, he’ll curl up on a cot for a few hours before making the return trip.

The 200-ton locomotive at the rear of the train pushes six passenger cars and the cab control car. It’s an express, and ahead the signals are green. So Dotson “jumps it up” to the maximum speed — 70 mph. He crosses the Fox River, which sparkles in the sunlight.

In the distance, he sees a school bus. It’s moving slowly across the tracks, but there’s no reason to panic. Dotson nudges the brake handle — just in case — and blows the train whistle: two long blasts, a short, another long.

But something is wrong. The rear of the bus remains on the tracks. Dotson pumps several short blasts on the airhorn. He keeps at it because the bus isn’t moving. As the train hurtles forward, he slams the brake handle all the way.

That’s the point in the dream when he always wakes up, shaking, just before the impact.

The collision was real enough. It occurred in the northwest suburbs of Chicago, when an inexperienced school bus driver misjudged the overhang of the bus. The resulting collision affected students at Northern Illinois University, where many had younger siblings still in Cary Grove high school or knew somebody who did or had attended that school.

Twenty-five years ago Sunday, Ford Dotson Jr.’s train smashed into a school bus in Fox River Grove. It wasn’t any dream. Seven teenagers, all of them students at Cary-Grove High School, were killed: Jeffrey Clark, Stephanie Fulham, Susanna Guzman, Michael Hoffman, Joe Kalte, Shawn Robinson and Tiffany Schneider. The bus driver and 24 other passengers were injured.

Two of the students on the bus might have chosen their subsequent work in public service as a consequence.

As Dotson’s 7 a.m. train from Crystal Lake, with 120 passengers and three crew members, headed down the tracks toward the Algonquin crossing that day 25 years ago, Brian Marino, a Cary-Grove High School freshman, was delighted. That was because he and his identical twin brother Michael would be late to school, but no one could blame them. Bus driver Patricia Catencamp — a substitute who’d never driven the route before — was running 20 minutes behind schedule.

Marino was sitting near the front of the bus. He’d been heading for the back but was pulled into the seat by two friends. His twin continued down the aisle.

Catencamp stopped before coming to the tracks, looked left and right, she’d later recall, then began to pull across. She stopped on the other side because the light was red, not realizing her bus hadn’t fully cleared the tracks.

“It never entered my mind that there wasn’t enough room for that bus to fit,” Catencamp, who couldn’t be reached for this story, would later tell investigators.

When the bell began to clang and the gate arm banged the top of the bus, some of the students called out to her, “We’re still on the tracks!” But all she heard was a garble of chatter.

“Move the bus! Move the bus!” students, now panicked, yelled.

By then, it was too late.

The train was going 69 mph when it hit the rear left of the bus, spinning it 180 degrees and slicing the cab from the chassis like a machete through cake.

The twins are now firefighter-paramedics in Crystal Lake. They, and the other survivors, in both senses of the term, are still dealing with the memories.  The highway department has since redesigned the crossing, and the traffic signals are interlocked with the crossing gates in such a way as to allow traffic stuck between the tracks and the signal to clear the level crossing.

Cross crossings cautiously.