roadblock

A literal roadblock is a barricade or obstruction that's meant to block traffic. A figurative roadblock is any situation you encounter that makes it difficult or impossible to do what you want or need to do.

When a driver encounters a roadblock, she has to stop and go back, or to take a detour and use a different route. This sort of roadblock might be set up to divert cars away from construction or an accident. Other roadblocks are obstructions to progress, like a lawsuit that halts construction on a building or the high cost of something: "The price of converting to a solar water heater was a roadblock to our plans."