Setting aside the cost, building that bridge will take a long time.
Literal
Costs [topic-は] aside [as for-として], that bridge [object-を] build [for-には] long time [subject-が] take [probably-だろう].
~は別として means 'setting aside X, apart from X.' This brackets the cost issue to focus on time. ~だろう adds conjecture. The pattern is useful for narrowing discussion to one factor.