They plotted to do this once before, and they don't like to be foiled, remember? So I'd really be on the lookout for this, too. Plus, unless the bridges and tunnels (under whatever authority they may be) have gotten rid of their Al Fuqra employees, they have a built-in staff of terrorists or terrorist sympathizers.
Note the absolute mania on the part of the airport authorities to get rid of all airport workers using phoney documents. There are other workers just as critical who work at buildings and landmarks. I doubt the tunnel people have gotten rid of the Al Furqa members or even have looked into it.