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Ngs Benchmarks In Canada

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Both the Canadian and US databases include United States NGS benchmarks that are physically located in Canada. In my case, there are a number in my immediate area -- all from around 1943, presumably from when they were building the Alaska highway.


Is it an oversight that none of these appear in the Geocaching.com database? Is there any way they can be added?


For examples, look at PIDs TT3918-21.

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Both the Canadian and US databases include United States NGS benchmarks that are physically located in Canada. In my case, there are a number in my immediate area -- all from around 1943, presumably from when they were building the Alaska highway.


Is it an oversight that none of these appear in the Geocaching.com database? Is there any way they can be added?


For examples, look at PIDs TT3918-21.

I did just what you said. TT3918 is not in GC database and when I searched NGS, this is what I got even when I marked the destroyed box:

-      O        Outside NGS Publication Area                              -

-                                                                          -

-                                                                          -

-  NOTE - Stations found in this listing may still have a valid            -

-          datasheet produced by use of other publishable values.          -

-          For example, an ADJUSTED height may be non-publishable          -

-          but a good GPS height might be found on the datasheet.          -

-          This listing does not imply that values found on the datasheet  -

-          are restricted.  If it's on the datasheet, use it.              -

-                                                                          -


  Pid    Name                          Lat        Lon        Elev    O o Hv

  ------ ------------------------------ ---------- ----------- -------- - - --

>TT3918 B 1                            60 40 50. /135 02 06.                O

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Yeah, well that is the catch here. They are listed in the NGS database but they have no datasheet with them. Here is an example datasheet from the Canadian database, I believe it is for US PID TT-3920.




Thu Sep 23 12:01:42 EDT 2004

Station 1 of 1






Unique Number : 43Y024

Name : C-1-1943

Established By : United States Survey Agencies (National Geodetic Survey And

Province : YT

Prov. Identifier : None

NTS Map No : 105D11




Method : Scaled

Latitude : N60° 39' 36"

Longitude : W135° 01' 59"

Agency : Geodetic Survey Division - NRCan

UTM : Zone = 8 N = 6724918 m E = 498196 m




Vertical Datum : CGVD28

Elevation : 724.128 m

Order : First Order

Method : Differential

Adjustment Line : VA192

Published Year : 1948




Marker Type : Permanent Agency Marker

Inspected in : 1943

Status : Good

Inspection Comments : None






HISTORICAL COORDINATES NOTE: Coordinates listed below are no longer maintained by GSD.





60135 VA192


As you can see, it hasn't been found or verified since 1943.


Seems like kind of an interesting project -- trying to relocate some of the history of the Alaska highway through these benchmarks.


I was out last night looking for this one, placed near the old White Pass and Yukon Route railway from Skagway. No luck at all. The coords were off -- maybe a problem with wrong datum -- and most of the landmarks they refer to are no longer in existence. I'll be back out tonight. ;)

Edited by Gonzo-YT
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The US, back in the WWII days did a lot of Geodetic Surveying all over the place. I have not come across the Alcan Highway in the History yet, but I have not read it all yet. I can say that it would make perfect sense for them to have been there. I have Built a few miles of Road in my day and you don't do it without Elevations to establish grades. Without Control, The bridges would look pretty funny.


I have read where the USC&GS did work a lot of Alaska in the 50's, I know they were there earlier than that too. The Army Corps of Engineers Built the Alcan during the War so I am sure the Geodetic work was in support of them. During WWII I read that thee were USC&GS personnel taken Prisoner in the Philippines, as we completely Triangulated a lot of south sea islands.


There are a couple guys who posts on here, Dave D, Who is with the NGS, and Dan Vull,He was a Geodetic Surveyor in the USAF for quite a while. If they come across this thread, they may have some insights. I have never read what kind of monuments the USAF Set, they could have set standard monuments or they may have had discs that were unique to their work. but I have read a lot of the information I could find about the USAF Geodetic Surveyors and they Did work in the Caribbean, S. America, S.E. Asia, as well as some stateside. It is a cool study in the spare time. In addition, there are other people here who may know something.


I can tell you that the Station you found was used for Elevation. It is a First Order Bench Mark Station, and was scaled off of a Map for latitude and longitude. You could tighten up its whereabouts quite nicely with your GPS, The Datum used for it's elev. is 1928 Datum. They had a different idea of how to determine Geoid Height back then, and it was not an earth centered Datum. I would not take that number as gospel today, but if that number could be properly converted it is a First Order Bench. I'd level off of it no problem. I am not sure, as this Station is in canadian Territory, but there may be a link under Tools on the NGS website that may have a way to convert the Datum to NAVD 88


I remember el Camino, offering a PID prefix grid map at one time, and Rogbarn making a digital printout of one. In the printed map that el Camino had, it could be seen that the grid overlapped the US-Canadian Border. It is pretty obvious that to properly locate the boundary, some cross boundary triangulation would be necessary, and as an agency, I can see why though they did monument the stations across the border, it would not be necessary to maintain the data for them after they served their purpose. They now fall outside of the legal territory.


This is cool Gonzo, Thanks for bringing this to the table. The Alcan Highway is something I had not thought of.



Edited by evenfall
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I found an old NGS benchmark last night. Not one of the ones I was originally looking for, however. This one is located quite close to the Alaska highway, within the city limits of Whitehorse, Yukon. This particular monument is used by the Canadian Gravity Standardization Network so I had newer data on where to find it.


Based on coordinates and information this one is TT3907. The monument just reads D/1943, as far as I can tell, but hard to say -- it's pretty banged up.




More photos and information are available in this geocache log.


I plan on going out tonight to try to find three old NGS benchmarks along the old White Pass train route.




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I'm really keen on finding some of these old US C&GS benchmarks. To me, they are a really fascinating piece of the history of the old Alaska highway. They're also a really fun challenge to look for. :)


While a few have been re-used and incorporated into the Canadian system, many of them aren't listed. The NGS database shows them, but there are no datasheets on-line.


Is it possible that there are paper data sheets on file somewhere for these? Is there an agency to contact for copies?


I also plan on talking to some of the surveyors around town to see if they have any leads.


Here are some examples that I pulled from the NGS database:


TT3910 A 60 43 14. /135 02 57.

TT3919 A 1 60 40 22. /135 02 26.

TT3914 AIRPORT ASTRO 60 41 49. /135 03 24.

TT3915 AIRPORT ASTRO RM 1 60 42 01. /135 03 45.

TT3916 AIRPORT ASTRO RM 2 60 42 01. /135 03 46.

TT3909 B 60 42 50. /135 04 55.

TT3918 B 1 60 40 50. /135 02 06.

TT3911 BEACON (CTS) 60 42 50. /135 03 38.

TT3908 C 60 43 24. /135 04 58.

TT3920 C 1 60 39 34. /135 01 59.

TT3907 D 60 44 22. /135 06 10.

TT3921 D 1 60 38 44. /135 00 20.

TT3906 E 60 44 36. /135 07 14.

TT3941 E 1 60 38 02. /134 59 49.

TT3912 F 60 42 47. /135 03 42.

TT3942 F 1 60 37 16. /134 59 39.

TT3905 G 60 44 48. /135 08 31.

TT3943 G 1 60 36 27. /134 58 55.

TT3958 H 60 45 42. /135 08 15.

TT3944 H 1 60 35 49. /134 57 55.

TT3945 J 1 60 35 04. /134 56 55.

TT3946 K 1 60 34 36. /134 55 36.

TT3947 L 1 60 33 45. /134 55 38.

TT3948 M 1 60 32 42. /134 55 27.

TT3949 P 7 R 60 32 10. /134 55 04.

TY8051 WHITEHORSE 7284 60 42 40.4/135 04 37.4

DE6615 WHITEHORSE CORS ARP 60 45 01.8/135 13 19.5

DE6616 WHITEHORSE CORS L1 PHASE CENTE 60 45 01.8/135 13 19.5

DE6617 WHITEHORSE CORS MON. 60 45 01.8/135 13 19.5

TT3917 Z 60 41 39. /135 02 41.

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I like the idea of what you want to do. I enjoy the history of these things and since the Stations in your area were set by the CGS as a part of a project by the US Army, through Canada for the ALCAN Highway during World War II, and it is a history we share. I have read and seen movies of the history, and I have met a few men who worked on the ALCAN. It was as frontier as you can imagine. When you think about how difficult the terrain was and what the tools were like in that era it is a simply amazing feat of engineering given the challenging timeline they had. It was War, and the War was near Alaska in many ways.


You have done a good bit of foot work. There may be more to these monuments in Canada along the Highway than is easy to know using the tools we generally have available. I do not have the right to volunteer services that are not mine to offer but I have an idea. There is a member of the forum here who posts from time to time. He has access to data that is not generally available to most as he is the Chief Geodetic Surveyor of the National Geodetic Survey. His name is DaveD here on the forum.


It is an odd request and not really in the current NGS mission, but perhaps Dave may know if there is any way of accessing the old obsolete datasheets to these Stations so that perhaps you could recover them for historical purposes. We are making a big event here in the states over the 200 year anniversary of Lewis and Clark. The ALCAN has historic importance too. It is possible that the NGS may still have the files archived. Dave? if your are listening, Can you shed a little light on these CGS Stations in the Yukon Territories along the Alaskan Highway? Thanks in advance Dave,


Good Luck in the YT,



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Actually, this has already started me on a more ambitious project to document the history of these benchmarks.


The NOAA History site is just amazing. I found some old photos taken during that year and was able to find out that this expedition in 1943 was under the command of Lt. Cmdr (later Captain) John Bowie.


Through the NOAA and hopefully our own local archives, I hope to get some more information about that year. It will give me some work to do until spring, when I can go out and try to track down more of his survey monuments.

Edited by Gonzo-YT
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A History Question for DaveD,


Dave, if you have the time or may know off hand, the Alaska or Alcan Highway has had me wondering a few things that this topic brings to mind.


It is true that the USCG&S did the initial geodetic survey work along the Alaska Highway route probably to aid the Army Corps of Engineers in their road surveys. But when I think about the location of Yellowknife, Yukon Territory, That is a long long way from anywhere. (no offense Yellowknife)


Leveling Standards at that time were from the NGVD 29 Datum, so I precariously presume all the elevations for that leveling would correspond to that Datum at that time, and still would since NGS does not continue to update the data. Perhaps the Canadian government has adopted some of this work for themselves.


My primary curiosity is, what methods were used to extend established level lines into Canada, and this far into Canada? Did we come off of established control here in the States, or Alaska? I am not sure how much good control we had in Alaska at that time.


Also, Where did we bring Triangulation in from for this project? Did the CG&S bring triangulation up from the south from perhaps Western Washington? Did the Canadian Government have survey that could be used closer to the area where the highway was being built? What quality triangulation and leveling would have been considered adequate enough and efficient enough to keep the project surveyed at the pace the army needed to go? I somehow sense that First order work would have taken too much time and cost too much. With 2300 miles between Seattle and Fairbanks, most of it in some of the toughest terrain there is to work in, it is apparent that this may have been no small undertaking.


Have you any thoughts or info off hand?


Thanks in advance Dave,



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Minor correction note that it's Whitehorse, not Yellowknife.


Most of the survey talk is above my head, but we're located quite close to the Alaskan coast. Skagway is actually one of the closest communities, about 140 km or so to the south.


If I recall correctly from the history, USC&GS did a lot of coastal work in Alaska during the 30's, which probably gave them a system to tie into.




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My Bad! Thanks for correcting me on the name. I knew what I was thinking but I didn't double check my thoughts...


You are right about the coastal work in Alaska in the 1930's but I was thinking about both Triangulation and Leveling. The initial coastal work in Alaska likely only consisted of Triangulation.


Differential Leveling is something that cannot be derived from any other observation other than a known, Bench Marked elevation. This means we have to start somewhere which is known and perform leveling on to where we need it to go. As a rule, in order to tie into a Datum or a reference of some kind, and we usually do have to, we cannot pick an arbitrary place and assign an elevation to it and go off leveling from that point, but rather we have to go to the nearest Bench Marked leveling we can find and continue the work of bringing the leveling into the area we need it and establish the monuments that we need to refer to regularly in that locale. Since NGVD 29, a vertical datum was established in the Continental US and lower Canada, It seems that Bench Marked elevations would have to be brought from there. I was just curious as to how. You have found dated Bench Mark data for 1943 and that would be the timeframe just after the highway was built, or rather blazed through.


As for the Triangulation, It could have been brought from Alaska, and that would seem to be the easy way, but I think it would have followed the highway route. The coast mountains would have been a lot of work to triangulate over even for 85 miles. Fairbanks was where they were going with the road, but they may have triangulated in from the coast near Whitehorse and went both directions from there to complete the work. Then there is the other matter of how the highway was built to deal with. The Army built the highway from both ends and met in the middle. That means they had to coordinate both ends by fly over at least, in order to meet in the middle at the same time, or at least it would seem so. They would have to establish some triangulation in the area to map this accurately, and it would have been all NAD 27 Datum Survey at the time, and any which lies in Canada is now abandoned by the NGS. If the Canadian government did not adopt this survey work, and include it in their data, then all that old control is still NAD 27 control.


I know they put the whole road in like a logging company would. They just took the easiest, most direct way they could find to do so. They didn't need established survey to determine ruling grades and curves, you make the curves fit what you need and keep to good established engineering practices for minimum radiuses and then perform simple on site leveling and do a little rise over run math to keep the road grades from becoming too steep for the trucks. This road was really a dirt road to begin with. It was navigable, sort of, and they surveyed what they did afterwards, obviously to facilitate mapping and further designed improvements. Improvements such as engineered steel or concrete bridges, super elevation for curves, widening, drainage, and maybe to blueprint what they did.


A detailed survey of the entire road itself would likely be performed at some time later and that would not have been a C&GS activity. The US Army may have done so, after the CG&S established survey control, as it was a military road then, but it is a wilderness road in two countries now. The C&GS was likely in the area at the same time the Army was, so it just makes me wonder what all they did. If they collaborated, and how. When you think about it, 10,607 U.S. soldiers built a road 1,522 miles long in 8 months. It seems to me they would have had to have triangulation established in order to survey the road from end to end at some point, but in 8 months and ahead of construction? Doubtful. It is a US Government road project, and they would want to Map it, there are all the grades and bridges and drainage which require engineering. Engineering needs Survey to plan with and so it goes... Shazam! Infrastructure! I cannot find anything in the NGS History about how they took part in this project and the History of the Alcan does not speak to the role the C&GS played.


Sure is fun to wonder about it though.



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Coast and Geodetic Survey did perform the triangulation and leveling along the route of the ALCAN highway during 1942-1944. The horizontal datum was NAD 27 and the vertical was NGVD 29. The data for C&GS marks in Canada should be available from Geodetic Survey Canada in Ottawa. NGS has a policy to not distribute data in Canada.

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