Joe is usually right about things but I don't think a "Strikes" topic would be very useful.
First, as he suggests, it could easily deflect into discussions of labor-management issues, in general or as related to particular strikes or potential strikes.
Second, the most useful place for warnings about possible strikes is on the boards for the countries affected. For example, Nigel is very conscientious about posting these for England, and some of our friends who live in France keep us informed the same way. If I'm planning a trip to a particular country, I try to keep up with posts relating to it so I'll know about strike risks, closures, maybe weather issues, anything that might affect my plans or my trip. A generalized "Strikes" forum would be another place to look, often unproductively, for something that might affect my trip. Might as well have a "Closures" forum or a "Weather" forum or a "Civil Disorder" forum, the list goes on.