SPAKE MAG B.M. 507.885
August 25, 2015 6:09 PM   Subscribe

What does B.M. 507.885 with a little metal cap next to it embossed SPAKE MAG mean? I saw this very carefully (and kind of beautifully) added to some concrete edging near the Southwestern Bell Telephone Building in my neighborhood and I'm wondering what it might mean. Construction symbols? Telecom stuff? A secret code or artwork of some sort?
posted by limeonaire to Technology (7 answers total)
That is a magnesium spike (Mag Spike) used as a survey bench mark (BM). The number is a reference.
posted by Yorrick at 6:19 PM on August 25, 2015

Actually I guess it says MAG SPIKE, like this for surveying? The paint makes it a little hard to read. This is making me think it's construction-related...

Oops, jinx!
posted by limeonaire at 6:19 PM on August 25, 2015

I think the number is more likely the elevation, 507.885' NAVD88
posted by hwyengr at 6:25 PM on August 25, 2015

If the 507.885 isn't the elevation, it might be the serial number for that particular bench mark. See if you can find a topographic map of the area around that building. Is there a bench mark indicated on the map? Do the numbers match up?
posted by Multicellular Exothermic at 6:57 PM on August 25, 2015

Here's some info on geocaching benchmarks.
posted by MuChao at 7:48 PM on August 25, 2015

The numbers are most likely the benchmark elevation of the property line. This is commonly used in construction and design to determine flood plain elevations and for determining slopes for surface drainage. It can also be used as a benchmark for setting flow line elevations of underground utilities.
posted by Benway at 7:21 AM on August 26, 2015

Here ya go.
posted by werkzeuger at 7:56 AM on August 26, 2015

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