Recently I was driving for the first time on the new section of the Chicago Loop on the way back to O'Hare Airport. The new section of the road was very impressive except that there was a parallel line of electricity distribution towers and they were very badly rusted. Arriving back in the UK I heard that Chicago is trying to sell iteself as the host of the 2016 Olympic Games. Quite a lot of passengers will have to pass these towers.
For oil rigs in the sea, steelwork is routinely thermally sprayed to prevent rust. Zinc can be used but aluminum is best. Why do people not use thermal spraying on land??

Living in Canada, I can tell you that all North American, cold climate hydros with ACSR supporting towers adjacent to highways and freeways suffer from mild salt fog corrosion. The granules of salt of course are spread on the road surfaces in the wintertime to convert dangerous ice and snow into a safe but corrosive briny solution. The fog is created by the high speed passage of vehicles and then is moved about by the wind.

Worse yet is the fact that the aluminum conductor and possibly the steel support center core of the cable are also corroded. Pitting corrosion on the surface of the aluminum strands can lead to loss of a small fraction of the power being transmitted.

The corrosion on the towers, although unsightly, is really not that serious and the rusted towers will stand for many, many decades. That is why they are not thermally sprayed as you have described in your much more serious corrosion, maritime location example. Thus cost is the primary reason that thermal spraying is not done.

Perhaps the Commonwealth Edison will spruce up the towers you have referenced if Chicago wins the right to host the 2016 Olympic Games.

For those readers who want to know more about thermal spraying, please follow the link below:

www.gordonengland.co.uk/tsc.htm

Regards,
Peter J. Stewart-Hay