A Construction or Detour Blockade is the attempt to isolate the player from a certain area until that player reaches the requirements to move on to the next island or area.
The Shoreside Lift Bridge Blockade in GTA 3. The player is located on Staunton Island and the bridge leads to Shoreside Vale.
Mostly all Grand Theft Auto games have used this idea of isolation but Grand Theft Auto 3 started the major Blockade idea by first having the Callahan Bridge cut off from the rest of the city by the bomb the Colombian Cartel dropped on the bridge in 2001 to help one of their own escape from the police convoy. This method is officially known as the "Broken Bridge" method of cutting off players.