[Talk-ca] (no subject)

[Connors, Bernie (SNB)]

Hello Clifford,

                I am a surveying engineer and I recall one of my surveying professors telling us about the surveying of the Canada-US border along the 49th parallel.  Below is a snippet from Wikipedia (http://en.wikipedia.org/wiki/49th_parallel_north) that explains what I recall my professor told us, but in my own words, the surveyors in the 1800’s could not measure accurately enough to place the boundary monuments exactly on the 49th parallel.  Both countries have agreed to accept the location of the original boundary monuments as the international boundary.  The info below from Wikipedia indicates some monuments up to ½ mile from the 49th parallel.


Parts of the 49th parallel were originally surveyed using astronomical techniques that did not take into account slight departures of the Earth's shape from a simple ellipsoid<http://en.wikipedia.org/wiki/Ellipsoid>, or the deflection of the plumb-bob<http://en.wikipedia.org/wiki/Plumb-bob> by differences in terrestrial mass. Although the surveys were subject to such limitations of early to mid 19th-century technology, extremely accurate results were obtained. However, in some places the surveyed 49th parallel is as much as several hundred feet from the actual geographical 49th parallel for the currently adopted datum<http://en.wikipedia.org/wiki/Datum_(geodesy)>, WGS84<http://en.wikipedia.org/wiki/WGS84>. The Digital Chart of the World<http://en.wikipedia.org/wiki/Digital_Chart_of_the_World> (DCW), which uses the Clarke 1866 ellipsoid, reports the border on average at latitude 48° 59′ 51″ north, roughly 270 metres (886 ft) south of the modern 49th parallel. It ranges between 48° 59′ 25″ and 49° 0′ 10″ north, respectively 810 metres (2,657 ft) and 590 metres (1,936 ft) on either side of the average. In any case, the Earth's North Pole moves around slightly, notionally moving the 49th and other parallels with it; see polar motion<http://en.wikipedia.org/wiki/Polar_motion>.

As per treaty, lines between original established monuments (1861) are straight lines on the chord, rather than curved lines on the tangent, which generally keeps the boundary some distance from 49 degrees north.

In 1909 the United States, United Kingdom and Canada signed and ratified a treaty confirming the original survey lines as the official and permanent international border. Nevertheless, the difference of the survey from the geographical 49th parallel was argued in front of the Washington Supreme Court<http://en.wikipedia.org/wiki/Washington_Supreme_Court> in the case of State of Washington v. Norman, under the premise that Washington did not properly incorporate the portions of land north of the geographical 49th parallel, as laid out by detailed GPS<http://en.wikipedia.org/wiki/Global_Positioning_System>surveying. The court decided against the premise, ruling that the internationally surveyed boundary also served as the state boundary, regardless of its actual position.

Bernie.
--
Bernie Connors, P.Eng
Land Information Infrastructure Unit, SNB
bernie.connors at snb.ca<mailto:bernie.connors at snb.ca>


From: Clifford Snow [mailto:clifford at snowandsnow.us]
Sent: Tuesday, 2012-09-18 00:16
To: talk-ca at openstreetmap.org
Subject: [Talk-ca] (no subject)

I'm doing some work in the Washington State and noticed some problems along the border between BC and Washington State. I asked for help on the talk-us mailing list.

I originally though the border was incorrect.  However, because the border doesn't track exactly along the 49th parallel there appears to be some administrative areas that don't match up with the actual border.  See http://www.openstreetmap.org/?lat=48.9803&lon=-121.7579&zoom=12&layers=M


Paul Norman wrote:
On Mon, Sep 17, 2012 at 5:49 PM, Paul Norman <penorman at mac.com<mailto:penorman at mac.com>> wrote:
The survey points are based on IBC data (which they view as PD) and are supposed to be accurate within a few cm and the limits of NAD83 to WGS84 conversion (a few more cm).

I’ve verified a few by the lower mainland with survey and against a few sources of accurate imagery and their data seems accurate within the limits of the imagery.

You can see a clearing along parts of the border in that area so it’s accurate to within 20 meters.

I know that Washington State argued that they were not responsible for the border costs in Blaine because it was not part of the state since the state ended at the 49th parallel and the border is north of the 49th there.

What I’ll do is go and eliminate duplicate border ways, like I did with the lower mainland.

There is a large multipolygon with a source of "CanVec 6.0 - NRCan" that should probably extend to the border. However I'm not sure. I'm wondering if anyone in Canada could investigate. The area is defined as natural=wood.

BTW - I'm using USDA National Forest Services Topo Maps to add in rivers, streams, etc. I see streams coming into the US from BC, but we don't have any corresponding stream in Washington.

Clifford

I have promised to cut down on my swearing and drinking, which I have.  Unfortunately, this has left me dim-witted and nearly speechless. Adapted from The Lion by Nelson DeMille

-or-

If you can't explain it simply, you don't understand it well enough.  Albert Einstein

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