That driver would have been startled, as were these Members.
I had the pleasure of watching several Members round up a horse on British Columbia's Highway 97 in the Cariboo.
A mare had gotten loose and was running on the four lane highway. Members blocked the road with their PCs in both directions then others moved slowly toward the horse encouraging her into a fenced dead-end. During the "pursuit" a Member called a cowboy friend who arrived quickly with a lariat and had the steed under control quickly.
Great post. Reminds me of McCloud in New York City.
This is very cool. I used to patrol on horseback Glacier National Park which borders the Canadian border.