Typically, an aircraft landing on a highway would indicate a serious problem, perhaps a mechanical issue or medical emergency with one of the pilots... That is, unless said highway was one of many built to act as a takeoff and landing strip. Many were, and still are, located in Europe and Asia, waiting to be needed in wartime. These types of roadways are called "highways strips." They are usually a long, straight section of the highway where there are either removable or no central… (www.msn.com) さらに...
Interesting! There's an old urban legend of the US interstate system having a similar feature, and the Snopes article even mentions that a "few countries do use some of their roads as military air strips," but I was never aware of the actual details.
https://www.snopes.com/fact-check/landing-of-hope-and-glory/