Designed as the only road tunnel to link two islands in Liberty City, the Booth Tunnel, along with the Hickey Bridge to the north, are the only points of access into Alderney via car; it connects northern Westminster in Algonquin to southern Alderney City in Alderney. While the tunnel is a four lane, two direction connection, the tunnel's road bottlenecks to two lane throughfares at both ends of the tunnel, occasionally resulting in the player encountering difficulty exiting one end of the tunnel, especially at the Alderney end, which may not provide sufficient room for the player's car to squeeze though its opening. The prominent mission it was used in was the Tunnel of Death.
The tunnel is guarded by the LCPD officers with police-booths at both ends, which may occasionally depict a police officer inspecting the trunk of a parked car; the tunnel also comes equipped with LED signage that inform drivers of safety tips and security announcements. Mavericks also spawn on helipads at both ends of the tunnel: One over the Alderney end of the Booth Tunnel and the other in front of the tunnle's ventilation tower on the Algonquin end; the latter is a popular spot for multiplayer, especially for Free Mode. In The Ballad of Gay Tony, a Swift initially spawns at the Alderney end, only to be replaced by a Buzzard upon completion of the game's storyline.
- An interesting sight can be witnessed over the Algonquin access road to the Booth Tunnel: due to the topography of the land (the further inland you go, the higher the elevation), a short segment of the A/J Algonquin Outer Line, which is in a subway, actually passes over the sloping, surface-level access road.
- If you enter the Booth Tunnel on the Alderney side it looks white inside on the ground but no matter how fast you go towards it, it would go to the greyish color.
- Booth Tunnel (GTA4) (Algonquin end).jpg
The Algonquin end, with a passing Algonquin Outer Line train in sight.
- Booth Tunnel (GTA4) (interior, Alderney side).jpg
The interior of the tunnel, as viewed from the Alderney side.
- Booth Tunnel (GTA4) (border).jpg
An Algonquin-Alderney border marker, denoting where Algonquin and Alderney starts or ends.