A Roman conquest of Germania built around engineering and coercion

As a Roman governor in Gaul in 6 AD, how would you attempt to conquer all of Germania?

The proposed counterfactual uses concentrated legions, slow advances, road and bridge building, forest clearance and extreme coercion to reduce the risk of an isolated marching column.

The proposed campaign begins with roads and bridges, supported by as many legions and troops as can be assembled. Forest clearance and a slow advance are intended to deny an opponent opportunities to ambush an extended marching column. Cleared timber would also supply bridge construction. Reliance on local German scouts is explicitly rejected. The plan invokes destruction, punitive violence and crucifixion as methods available within the imagined Roman commander's outlook. That outlook is explicitly separated from a modern recommendation. References to the Punic Wars and salting the earth provide a comparison for the proposed devastation.