Sector B Coolant Reserve

"Hey, you got the wrong airlock, Mr. Freeman. You know I can't let you through here."

- Security guard

Sector B Coolant Reserve is one of the seven main sectors of the Black Mesa Research Facility. Connected to the Blue Line of the Black Mesa Transit System, it is first seen by Gordon Freeman when he escapes from Sector C during Half-Life, and seen again during the tram ride at the start of Blue Shift. The "coolant reserve" itself is never seen, unless it consists of the area seen under the Freight Yard in Blue Shift.

Sewer system
That section is connected at one side to Sector C, and at another to Sector D, from an elevator.

When coming from Sector C, a series of small rooms lead to an area named "D-475KL", which include what is most likely a small sewer system. There Freeman comes across Houndeyes, Headcrabs, Zombies, surviving scientists, and sees the G-Man for the first time since the incident. After that the player comes upon a massive freight elevator used to move large goods or even entire vehicles, a piece of equipment that will come to be seen many times around Black Mesa, to the lower levels of Sector B.

Lower Canal
The next area is the Lower Canal. It is infested by Barnacles and Headcrabs, as well as one of the several Bullsquids found in the area. It is crossed by a bridge that leads to the Sector D elevator, but it has collapsed. To cross the canal, several maintenance areas must be traversed, as well as a big room featuring a track system for crate transportation, not in function at that time.

Sector B Line
Sector B Line is one of the few Sector-related Black Mesa Transit System to be seen/mentioned during the games. A medium-security line where can be found the Area 9 Security Checkpoint, it is the line taken by Barney Calhoun from Area 8 Topside Dormitories through the East Personnel Entrance, and leading to Area 9 Central Transit Hub. Along Sector B Line can be seen a fast food outlet, a lab, and a lavomat.

East Personnel Entrance
Connects Area 8 Topside Dormitories to the rest of the facility through the Transit System. Above it floats an orange flag of Black Mesa. Its name suggests there are other such entrances.

Area 9 Security Checkpoint
Likely located not far from Area 9 Central Transit Hub, Area 9 Security Checkpoint is first seen during Barney Calhoun's tram ride at the start of Blue Shift. There Barney Calhoun leaves the line he took at Area 8 Topside Dormitories to the Sector C Line. Area 9 Security Checkpoint apparently acts as one of the many transit security checkpoints throughout the Transit System. Trams that pass through that checkpoint can be rerouted to both the Sector B, C and E Lines.

List of appearances

 * Half-Life
 * Half-Life: Blue Shift