Combat bridging vehicle
From Halopedia, the Halo wiki
The combat bridging vehicle, colloquially known as a CBV, is a Covenant vehicle designed to launch a bridge of up to one kilometer in length over chasms that would otherwise be an obstacle to Covenant forces. The process to create this bridge so that Covenant forces can continue their advance takes less than a minute to complete. 
The combat bridging vehicle possesses articulated cylinders on the back of the unit that contain the bridging apparatus when it is ready to be deployed. The CBV itself possesses heavy-duty energy shielding in order to prevent the bridging equipment from being destroyed before it reaches its destination.  In the front of the vehicle is a bulbous driver's cabin with a canopy.
In 2526, during the Human-Covenant War, the Covenant deployed 3 CBVs with support from 100 armored personnel carriers (APCs) as well as several Wraiths and rapid assault vehicles (RAVs) on the planet Mesra in an attempt to cross a gorge and gain access to a mine and its resources. Blue Team was tasked with destroying the CBVs to prevent them from crossing the gorge. After the first two were destroyed, the Covenant pulled back their third vehicle and reinforced their wraiths with 50 combat support vehicles shortly after. 
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