Still begs the question as to why utility lines are still being hung on exposed poles in this day and age. C'mon USA - it's 2011! Let's get these things underground and out of harm's way. If we can drop $1 billion every three days being in Iraq, we can spend a little money here. Make it a project for the military if that will get it funded. Electricity is a strategic resource so it shouldn't be hard to justify it with all the "homeland security" legislation that's been passed. Call it an anti-terrorism measure if that's what it takes to get the ball rolling.
-40hz
Simple. Money. Exposed lines are cheaper to run, cheaper to fix, and cheaper to maintain. Since this isn't a government project, but rather a private firm. Even as heavily regulated as it is, it is still considered private and therefore gets no funding from the government. Therefore, to put everything underground would actually increase prices dramatically, and not JUST for the installation. Maintenance costs go up as well. Moreover, believe it or not, there is MORE OFTEN outages related to underground installations than there are for above ground installations. They may be more exposed, but people generally avoid the above ground ones. The in-ground installations are subject to all manner of rodent damage, water damage (insulation does break down over time), crushing, etc. But the single most common cause of in-ground damage is human digging.
People digging, even when properly permitted, either ignore, or misunderstand where a live line is running and cut it during digging. I can't tell you how many times contractors cut our lines while putting in septic tanks, sewer lines, or just new buildings while I was in the military as an electrician. We would mark it, have safety huddles with the contractors, and they STILL would cut lines thinking they were over to one side further than we marked them. Overhead lines only failed from human interference when someone hit a pole hard enough to drop it completely (it is a funny site to see a pole hanging by the line - and they are strapped on that tight), or does something completely stupid. Sure, they are more often subject to weather issues, but the lines rarely cause power issues because they are exposed. It is almost always the fuses to protect the lines or the power stations that are the issue, and those issues occur far less than human intervention issues.