Here in Sweden we have a lot of (military) airstrips that are incorporated into the public road network.
It's always strange when you bike on a rural road and it broadens to a four lane motorway straight ahead for a kilometer, and then it narrows again and meanders on.
When they were building the M25 motorway around London (about 120 miles for the loop) there were large sections that were built and not yet open to the public - much fun was had on fast motorbikes late at night! Though once the whole thing was open, it all got out of hand [0]. Having said that, back then you weren't risking serious jail term for high 3 figure speeds (on top of the risk of losing your licence, and potentially your life).
It's always strange when you bike on a rural road and it broadens to a four lane motorway straight ahead for a kilometer, and then it narrows again and meanders on.
An example: https://maps.app.goo.gl/ZCQ6rEk7W5jkHBZw7