Yellow jackets and wasp invasion
Because it's a bit early in the year to have numerous yellowjackets flying around, I suspect you might have solitary ground-nesting bees under your wooden walkway.
Even though each native solitary bee makes its own nest, many will congregate, side-by-side, in a choice area. If the insects at your place are native bees, the good news is that they don't sting; they're harmless.
Your insects may be the so-called "Tickle Bees" which fly from the playground at the nearby Sabin Elementary School. See https://xerces.org/2017/04/10/staff-story-the-tickle-bees-of-sabin-elementary/.
Please send several images of your insects so that we can verify their ID.
1) An overall view when a number are flying; 2) One or more insects resting on the path or nearby; 3) One or 2 individual insects.
You should be able to trap several. If so, it would be easy to take a picture of them after they chilled in the freezer for 10 minutes or so.
To catch one or several of the insects, set an overturned, large mouth jar or other clear container over one of the gaps where there is considerable activity. When one flies into the jar,slip a stiff piece of paper under the container, then turn the jar upright. (See attached image.)
I look forward to seeing your images.