posted on May, 29 2013 @ 05:15 AM
This is just a shot-in-the-dark, but when I did a search of BMQ (which is what the symbols appear to me to be), I discovered that there is a Quebec
company named Beton Mobile Quebec Inc. This company provides specialty concrete to the construction industry with many bridges and bridge repairs
among their past projects.
Perhaps this symbol is a self-promotional 'tag' for having been involved in supplying concrete for this bridge?
As for the "66", I'm not sure how that would fit in.