"You have the code to the armory and the detonator to ensure its destruction. Unfortunately the armory is on the far side of a crevasse. You need to activate the energy bridge that the Crimson Lance has built to get across."
Go down to the lowest area of the map, off the roads and west and northwest of plains where the Cheta Paws and Alpha Skags roam. Southwest of the ramp that the Bandit vehicles like to jump off is a New-U Station. Follow the path behind it that runs beneath a cliff. This will lead to a small building and bridge across the chasm. The way point will lie across the bridge.
Reaching the middle of the bridge will trigger a single BadassRocketeer to spawn. The Badass Rocketeer's rocket launcher is particularly hazardous on the narrow walkway suspended over the drop, and players must be careful not to fall when taking rocket fire.
Near the controls that activates the bridge to Road's End are two giant columns that will being to rise in a repeated regular pattern once the bridge is activated. Riding both columns to their peak will lead a player to a red chest and a Crimson Lance chest.
Completing the objective will cause a ramp near the controls and the bridge to fall down and give access to a walkway beyond that runs along the cliff. However, this seems to lead a dead end.