No, no, no. Do not get a PhD in civil engineering. In engineering fields, work experience and professional licensing are MUCH more important than another academic credential. Especially considering that it takes usually 4-5 years of work experience to become professionally licensed. If you do a PhD, you will probably only delay your entry into the work force by 5-7 years, and enter into a field where a PhD is not necessarily rewarded. Think long and hard about this. Talk to employers before you make your decision.
Overall, I don't think the PhD meshes well with your goals either, if you want to get into management. A PhD is typically NOT a path to management. Most PhDs hit a glass ceiling overseeing research groups, and usually do not find themselves in more mainstream corporate management.
As for MBAs: There are lots of engineers who have MBAs, but nothing to show for it besides the degree. If you go for an MBA, make sure you go to a top-tier school, and that you have a plan to leverage the degree.