I see toll roads as simplify a manifestation of US culture, in broad generality, being self-absorbed and/or not having a distrust for government. By being self-absorbed, I mean nobody wants to pay for anything that would go to the greater good of society. Toll roads and special tax investment zones, which we also have in Houston, are both work-arounds to overcome the constraints that have been levied on new tax revenue generation or caps placed on existing revenue generation. One of my observations when I was living in the Netherlands – brought on by a colleague who was complaining about the high taxation rate that he was subject to – was that everybody pays the same at the end of the day. It's just a different path to get there. The Netherlands (and many other European countries) are akin to being on the 'American Plan' (or all inclusive) while we in the US are on the ala carte plan (we pay separately for services). I don't see an ethical issue for engineers working on toll roads. It's the nature of the beast.