At the edge of a highway, someone cut a row of grooves into the asphalt.
Half an inch deep.
Evenly spaced, like a comb laid down in the dark.
The grooves have one job.
When a tire touches them, the whole car hums.
A low, ugly note that climbs the seat and reaches the hands before the mind has decided anything.
The wheel is already turning back.
Cars rarely leave a lane in one move.
They lean.
A tenth of an inch through a long curve.
Another tenth on the straight, where the road goes on being kind.
The paint stays where it was painted, and the car drifts across it a little at a time.
One night a sedan sits on this road, new and dark and expensive in the quiet way.
The cabin smells of leather warmed by the heater.
The suspension reads the surface hundreds of times a second and cancels what it can.
The glass is doubled.
The seats are stitched.
Potholes reach the driver as rumors.
The left tires find the grooves.
The note is there, only filtered, arriving as a murmur under the music.
Like a thumb dragged slowly along a table in another room.
The driver takes it for the sound of this particular road.
A hum that never stops becomes the floor.
He signals.
He keeps his distance.
He stays under the limit.
A lane chime once sounded on every long curve, and a month ago he found the setting that turned it off.
The tires stay on the grooves.
On a test bench, the strip would still make the same note.
The sedan would still soften it.
Both are working.
A rumble strip can only correct what it is allowed to shake.
Behind the sedan comes an old delivery van, seat springs showing through cracked vinyl.
The moment a tire touches the grooves, the steering column shudders and the driver pulls back.
A thermos on the passenger seat rolls left with every correction, then rolls back.
He has done it forty times tonight.
His hands know the note.
Then he sees the red lights ahead, sitting on the line.
Steady.
Unhurried.
A full mile of them.
Cars pick their line from whatever lights are in front.
At two in the morning the paint is a rumor and the eyes are heavy.
The van eases left.
Only a little, to see how it feels.
The note rises through the wheel, the same low hum, and now it has company.
The thermos stays where it is.
The first car over the line looks careless.
The second looks like traffic.
By the fourth, the grooves look like a lane.
Soon, leaving them looks strange.
In the sedan's mirror, headlights gather behind him, steady and patient.
They are the only report the cabin still carries.
Every pair agrees with the last.
The painted line runs beside them all, clean and white.
Nobody is looking at it.
The suspension is the easy thing to blame.
The van has none of it, and the van leaned all the same.
Ask the van driver, and he would take the suspension in a heartbeat.
His back has earned it.
A steady pair of red lights makes a convincing edge.
Somewhere past the next exit, the sedan signals off and is gone.
The lights behind it keep to the grooves for another mile, each one steering by the one ahead of it.
The first of them has already left.
Rain comes through around four.
By morning the highway is empty.
The grooves are still there along the edge, half an inch deep, each one holding a little water, waiting for a tire.
Same habit of steering by whatever is ahead shows up with a trail of footprints in The Path With All the Footprints, where a crowded path felt like proof until someone asked who had actually checked.
