traffic jam due to an accident; accident-induced congestion
Specifically refers to traffic congestion caused by a vehicular accident, as opposed to general congestion (渋滞) or rush-hour traffic.
I got caught in a traffic jam caused by an accident on the expressway.
Due to accident-induced congestion, I will likely be late.
渋滞 is a general term for traffic congestion, while 事故渋滞 specifies that the congestion is caused by an accident.
自然渋滞 refers to congestion that occurs naturally (e.g., due to high traffic volume), without a specific incident like an accident.
Compound of 事故 (accident) and 渋滞 (traffic jam).