Logjam and Roadblock

Logjam noun - A crowded mass (as of cars) that impedes or blocks movement.

Roadblock and logjam are semantically related. in traffic tie-up topic. In some cases you can use "Roadblock" instead a noun "Logjam".

Roadblock noun - Any condition that makes it difficult to make progress or to achieve an objective.

Logjam and roadblock are semantically related. You can use "Logjam" instead a noun "Roadblock".