Hoover Dam Bridge

I’m not an engineer but I have an appreciation for difficult engineering feats such as the completion of the bridge that bypasses the old Hoover Dam route crossing the Lower Colorado River between Nevada and Arizona, not too far from Las Vegas (here).  I assist the federal Bureau of Reclamation with their environmental and sustainability programs, so Hoover Dam is one of my “clients” you might say (but Reclamation has nothing to do with the highway bridge, to be clear).  On business trips to the area I’ve observed the bridge’s progress through these eight years of construction – the highway approach on each side of Black Canyon was no small feat of development either.

Is this project an environmental plus?  Can a huge concrete structure and 3+ miles of roadway be environmentally friendly when all factors are taken into consideration?  I confess I haven’t looked into the specific environmental impacts of this bridge project, but just consider one component: the future vehicle fuels savings from travelers not creeping along the former six mile roadway that physically crossed the top of the dam. And after 9/11 for security reasons heavy trucks were not allowed over Hoover Dam and had to make a 23 mile detour through Laughlin, NV. How much petro will this bridge project save in the next 5, 10 or 30 years?  It would be interesting to know.