pike
We must have a couple of hundred roads in my state that have the name "pike" attached. It's a very common term in the eastern half of the United States. There was a time in many states when darned near every road was called a "pike."
The closest to my house is "Spiceland Pike." It's the main road, of course, that goes through Spiceland. We also have "Old Spiceland Pike," which is the road that used to be the main road through Spiceland. Both roads are small, curvy, and slow.
Most newer dictionaries get this wrong, seeming to think that "pike" is short for "Turnpike," and it isn't. Nor is a "pike" usually a broad, fast roadway, though it may have been considered such when it was built. It's most often a state highway at best, and often just a side road to a specific place.
Traditionally, a "turnpike" is actually not a road at all. It's the gate across a toll road where you pay the toll, and the term has been in use for at least four hundred years. It's pretty hard to imagine anything coming down the turnpike, even though the road itself is now usually referred to as a "turnpike" because it has turnpikes on it. Now we just refer to the toll booth, rather than the gate.
But the expression "coming down the pike" is a very old one. Far older than modern, high speed roads, and "pike" isn't short for anything. It's just another way of saying "coming down the road."