Police Roadblocks are a feature in every Grand Theft Auto game except Grand Theft Auto 1.
Roadblocks are set up on the road in an attempt to block the player in pursuit at a 3+ Star wanted level.
At three stars the roadblocks are comprised of police cruisers, except for Grand Theft Auto V, where they are replaced by Police Transporters. Occasionally, the vehicle will sit in front of a spike strip, to further effect the player. At four stars they are replaced by Enforcers (Police Riot in GTA V). At five stars the roadblocks are replaced by FBI (FIB in HD Universe) vehicles, and a six stars they are replaced by Barracks.
GTA 1 introduced with only police cars blocking the roads, and the same goes with GTA London '69 and GTA London '61, in GTA 2 it is easier for the player to escape as there are laced gaps between neighboring vehicles, secured only by easy-to-be-rammed-through barriers, that even leave the player's car nearly undamaged. GTA 2 also introduced higher level police, FBI and military road blocks.
Roadblocks are featured in all of the games in the 3D Universe. In GTA Vice City, GTA Liberty City Stories and GTA Vice City Stories, the Police will set up stingers and driving over them will result in bursting the players tires and the player will be unable to drive the car properly. In GTA San Andreas, in the initial cutscene of Puncture Wounds there is a reference to the police using stingers, but they never actually set them up as a part of a roadblock.
Depending of the wanted level, some variations will occur during the pursuit. For a 2 stars level, police cars are placed on the road and some police officers will be waiting to shoot the player. For a 3 stars level, there would be officers deploying spike strips in order to pop the vehicle's tires. For a 4 stars level, transport vans are used, which would be heavy for some basic cars. For a 5 stars level, undercover SUVs are used, which are lighter than the vans, but are still heavy for basic cars. Finally, for a 6 star level, military transport trucks are used, being even heavier for most vehicle's classes.
GTA IV - GTA: Chinatown Wars
The changes from the previous games to GTA IV are much of the same but the Police will set up roadblocks on main bridges (those that connects the main islands) and the Booth Tunnel, on each entrance. On a locked island, they will put concrete block and a vehicle on each side preventing the player to pass through the bridge. This only occurs when the player has not unlocked all of the islands, although only the bridges to Alderney and Algonquin are blocked because the only way to Happiness Island is by helicopter or boat. Any attempt to cross these roadblocks will result in a wanted level of 6 stars.
On a normal gameplay, every time that the player makes a wanted level of 3 stars, the NOOSE will start deploying their vehicles to make a roadblock, which is generally composed by the vehicle that is pursuing (NOOSE Cruiser or NOOSE Patriot). When the same reaches 4 stars, there would be either Enforcers, Police Patrols or Police Cruisers, which the later two are only placed if the FIB is pursuing the player. As seen in GTA 2, there are various easy-to-be-rammed-through barriers.
Police Roadblocks reappear in Grand Theft Auto V, however they are slightly different.
Sometimes when the player has a 2 star wanted level, the LSPD will form roadblocks using their Interceptors. They are usually made of 1 to 2 cars, with officers pointing their weapons at the player, and cones/police barriers blocking the road. On three wanted stars, Police Transporters will be seen blocking two lanes of the road, with the opposite side being able to easily pass. However, when a Police Transporter is spotted blocking the road, there will usually be a Spike Strip after it, causing anyone to pass the van to be vulnerable to tires to been popped, losing control of the car, however, this can be avoided by fitting Bulletproof Tires to the car. Once the player passes the Police Transporter roadblock, the officer usually gets into the van, and begins to pursue the player. On four and five stars, NOOSE will sometimes deploy Police Riots to block the road, again, up to 5 Police Riots can be seen forming roadblocks on highways. These only usually appear when the use of explosives is used as a deterrent against police. If in a different case, standard Police Cruisers or Sheriff Cruisers will continue to form road blocks.
Note that not all roadblocks are always the same. For example, for a basic roadblock, two police cars are placed perpendicularly on the road, facing at the same orientation, while in another circumstance, a police car would be oriented straight to the road, surrounded by some traffic cones and some police officers ready to shoot the player. Unlike former games, any police officer will get in the vehicle that was set on the roadblock if the same fails to stop the player. Roadblocks on the highway are usually much larger, also dependent on the star occupied. Sometimes, up to 5 Police Cruisers can be seen blocking an entire side of a highway. These roadblocks can rarely be seen used on larger avenues within the city.
Roadblocks during Missions
During missions and heists, roadblocks are generally weaker, or larger. In The Jewel Store Job, a road block can be seen formed in the LS River. In The Big Score, roadblocks can be seen cornering up to three intersections in Rockford Hills, however this can only be seen apparent when the Subtle approach is chosen. In The Fleeca Job, roadblocks are unusually made up of Sheriff SUVs. Also, roadblocks over the river within the Cassidy Creek area can be seen made of FIB Grangers during Pacific Standard - Signal. In The Pacific Standard Job, a road block can be seen made up of two Police Cruisers and a large ramp at one side. Also during this mission, Sheriff SUVs can be found blocking the entrance to a tunnel in the Chiliad Mountain State Wilderness. Also, during Pacific Standard - Convoy, Merryweather can be seen forming military roadblocks using Barracks and Mesas. This is the only time Military roadblocks are seen in game.