Traffic congestion due to drivers' attention being simultaneously diverted to something, such as a collision or animals on or near the road. Primarily heard in US, South Africa. They were able to move the wreckage well off the road to allow cars to pass, but there remained a gaper's block on the highway for the better part of the morning.
See also: block
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.