Can you control particles velocity within a section of a path?

I’m trying to simulate freeway traffic using particle. You can randomize the velocity along the entire path, but can you specify a section of path with a specific velocity?

In this example, straightway at the start and end are on normal speed. Cars would slow down as they enter the banks and speed up when exit the banks. Can this be done with particle? Thanks.

I guess it’s not doable?