Originally posted by Jonna
As far as I can tell they come to an end at the entrance to the westbound Interstate 80 highway. Here the arrows are a grouping of three with the
outer ones pointing east and the center one pointing west.

I don't know what they could be, but I don't think road races or bicycle routes would lead to I-80. Bicycles and pedestrians aren't allowed on it.
Or it may be a bike route and I misunderstood the original post.
It would seem more like some sort of evacuation route to I-80.