From Halopedia, the Halo wiki
A subdivision of the corporation, Tterrab Highway Authority, worked on highways since its corporate symbol, a lower-case "a," is visible on the emergency doors in the highways of the NM 105 E, as well as highway signs of the Tsavo Highway.
Tterrab Industries may also have worked on Wind Power Station 7 on Zanzibar Island, as its symbol can be seen on many of the signs around the station. On the abandoned UNSC Weather Station Z/41 in the Arctic, a rectangular piece of equipment is seen in the server hallway, fenced off, with the Tterrabb logo stamped on the front.
In October 2552, during the Battle of Earth, Mombasa was abandoned and Tterrab Industries appears to have been locked up. The area in front of it, however, was the site of intense fighting between Marines of A Company and Covenant Wraith tanks, eventually culminating when the Master Chief and a Scarab arrived in the area. The building was not harmed, but it is presumed it was later destroyed anyway when the city was glassed by the Covenant in order to uncover the Forerunner portal generator buried under it.
- "Tterrab" backwards spells "Barrett", which references Bungie level designer Chris Barrett.
- The sign on the Tterrab building in the level Metropolis in Halo 2 read "Askloun" in some earlier builds. A similarly named company, "Asklon", would later appear in Halo 3: ODST.
- In Halo 2: Anniversary the sign of "Tterrab Industries" headquarters changed into "Franchbot Industries".