There are swappable items between two groups. Tie can also be part of a railroad/railway, and spike (and maybe also joint) can be a fastener.

Can we please have an end to clueless people pointing out what a red herring is? WE KNOW there are "swappable items" That's where the challenge comes. Otherwise, it's just four clearly delineated lists.
Fool Moron Imbecile Cretin See how obvious that is?

David, there's a difference between a red herring and multiple correct solutions. Take a look at "One Correct Solution" on the About page.

I've read it. "Problematic" is a semantic term for extra challenging in regards to having even two or three clues that can cross over into other categories. It can be what makes a puzzle that is initially a "stand and stare" so satisfying when you eliminate certain combinations. The 16 clicks and you're done grids may have their fans. They're fun, too. But there's a reason that the hard and fiendish descriptions exist.

For problematic read invalid. Seems d A g is the only one who doesn't understand red-herrings.

Phillips was NEVER a Formula 1 team. I call shenanigans. Indy 500 yes. F1, no.