The secret life of utility poles

poletag.jpg
Photo: Denis Cousineau

A picture in the Metroblogging Vancouver flickr pool reminded me of something my father had told me, and that led me down a few odd paths to discover some poorly-documented stuff. But here’s the short version: utility poles can serve as the poor man’s urban GPS. Amaze your friends.

Look at that photo up there. what you are seeing is a picture of the identity tag on a utility pole. All poles have them. It’s part of the system by which utility poles are tracked by their respective owners. BC Hydro estimates its own pole inventory at 861,000 province-wide, an inventory item they value in the billions of dollars. They even have an exhaustive PDF document describing how long their poles last: The Performance of Wood Poles in BC Hydro’s Distribution System.

Back to the tag. The numbers are the latitude and longitude of the pole in a slightly odd format, the year it was installed (’54), and the “JO” indicates this pole is jointly owned by Hydro and Telus.

The geographic coordinates are given thus: the first group indicates a longitude of [1]22 degrees, 55 minutes West: the leading “1” is dropped because that would be the same province-wide. The number below gives the distance from the “minute line” in tens of feet, so this number tells us we are 181[0] feet from 122d55′ W. They do this because while you need to know the location of the pole, the next most interesting number is its distance from adjacent utility poles. Giving the coordinates in feet instead of seconds of latitude and longitude makes that easier.

The latitude is 49 degrees, 15 minutes, 38[0] feet North. That puts this particular pole about 16.5 miles from the 49th parallel, as the crow flies.

So that’s the old system. the “0070” might be the height of the pole in feet. My sources aren’t sure.

Somewhere between the 1950s and today, Hydro and Telus changed their pole-marking system. Erich Harvey’s photo shows us an example of the newer tag:

Maybe it’s not obvious, but these coordinates are not degrees of latitude and longitude. In fact, they’re much simpler. These are UTM coordinates, and if you have a good set of topographic maps and know how to use them, these coordinates will tell you exactly where you are. The first thing to know is that Vancouver is in UTM zone 10U. The first number group, normally written as 486882, is the “Easting”. The second group, written as 5456835, is the “Northing”.

These are the distances, in metres, from the Southwest corner of the 10U grid square, which is 500 km on a side. The whys and the whats of this grid are bread and butter for surveyors, cartographers, and people who get around using map and compass, but for a starter, here’s a coordinates converter which I used to turn the UTM numbers into degrees, minutes, and seconds, which I then popped into Google Maps, which is how I found Erich’s utility pole, which I think was installed in 1987. The bottom number is probably a serial number, and I don’t know what “10388” means.

If anyone knows of a Google Maps hack that directly accepts UTM coordinates, let me know.

Sadly, I have found even newer utility poles that have no useful marks on them. The ID tag is reduced to a single serial number, with no apparent geographical data encoded on it. The good news is that Hydro has poles dating back to the fifties, so we won’t run out of geolocated utility poles for quite some time.

Bonus information: How to grow trees that won’t drive BC Hydro crazy by wrecking your power lines.

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