Multiple disks in one entry, how to search/log?

[+rogbarn]

Certain types of markers will list several disks if you read the description carefully. Usually, these additional markes are reference and/or azimuth disks. Sometimes these markers have their own entry, I think it depends on who was filling out the paper work. But, many of the markers in my area are survey disks, they have only one entry and they almost always have an azimuth disk associated with them. If there is only one entry listing more than one disk, do you bother to find all of them? I try to find both but occansionally I can't find one or the other. Is a survey marker useful without an azimuth mark? Is an azimuth mark useful by itself? By my way of thinking, a survey disk is OK and I log it as found, but an azimuth mark by itself is useless and I log it as not found. Of course, I put details in the log listing in all cases.

[survey tech]

Reference marks and Azimuth marks are intended to make a Triangulation Station more useful to local surveyors, who may not have all the same long distance equipment that NGS has. But any one of the markers can still be useful by itself and should be equally respected.

[+Centaur]

I just got a horizontal benchmark disk ME2849. However it also listed 2 other reference mark disks that should have been near by. We were unable to find them. The discriptions for their locations were all refering to unnamed lamp posts (that may have been moved over time) but ayway we could not find the reference marks. How close/far are reference marks usually placed to the primary disk? The description also listed a disk placed way underground, what would that be used for ? Looking at the NGS data sheet provided a little better information then the info page here, but I have yet to decipher all the data thats provided on the NGS sheets. It appears that the 2 reference disks had PID numbers, but searching for them turned nothing up. The info also refered to using station 010 COC as an azimuth mark. Whats that mean exactly? and how does one find station 010 COC ?

Thanks!

-Centaur

------

Interesting tidbit - The datasheet copy here in the Groundspeak records read as:

 

ME2849|---------------------------------------------------------------------|

ME2849| PID Reference Object Distance Geod. Az |

ME2849| dddmmss.s |

ME2849| ME2831 CHICAGO A G CATH CH SPIRE APPROX. 3.2 KM 0393826.1 |

ME2849| ME2811 GRACE APPROX. 5.0 KM 1221033.0 |

ME2849| FOSTER RM 1 30.829 METERS 23519 |

ME2849| FOSTER RM 2 27.284 METERS 33643 |

ME2849|---------------------------------------------------------------------|

 

But the datasheet direct from the USG/NOAA site (which was the first one i looked at) read as:

 

ME2849|---------------------------------------------------------------------|

ME2849| PID Reference Object Distance Geod. Az |

ME2849| dddmmss.s |

ME2849| ME2831 CHICAGO A G CATH CH SPIRE APPROX. 3.2 KM 0393826.1 |

ME2849| ME2811 GRACE APPROX. 5.0 KM 1221033.0 |

ME2849| CM3516 FOSTER RM 1 30.829 METERS 23519 |

ME2849| CM3517 FOSTER RM 2 27.284 METERS 33643 |

ME2849|---------------------------------------------------------------------|

 

Note the reference disks have a PID (CM3516, CM3517) Yet as I said above, looking for these PID's dont come up with anything.

 

A) Why are they not in the Groundspeak copy?

How did they get in the USG copy but dont seem to be valid nor does the page seem to indicate any other updates. Does CM indicate anything?

 

Thanks!

 

[This message was edited by Centaur on August 21, 2002 at 06:54 AM.]

[+rogbarn]

From my experience, reference marks are usually 20 to 100 feet from the main station. Azimuth marks are usually 1/4 to 1/2 mile away. This is very rough and someone more knowledgable may clarify this. This particular description is poor in that the reference disks are not measured from the main station and only from points that are confusing, i.e. light poles. No wonder you had hard time finding them!

 

Again, from my experience (as a benchmark hunter only, no experience as a profession), the underground mark exists in case the surface mark is disturbed in any way. The underground mark remains to allow them to restore the surface mark to its correct location without a lot of expensive and time-consuming work.

 

From what I can tell, what looks like PID numbers on the reference disks are not. There are no PIDs like that on either geocaching or NGS.

 

One thing that I have learned is that surveyors refer to stations by their station name, aka designation. So, the reference to 010 COC is to a station by that name. If you use the NGS site to lookup by station you can find its datasheet. It is PID ME2851 and was reported not found in 1996.

 

Hope this helps.

[survey tech]

Looks like you guys are overlooking the distance to the reference marks, "30.829 meters 23519" & "27.284 meters 33643". These are the distances and directions to the ref. marks, if they are still there.

[+Centaur]

But they didnt help me find the disks. I even went so far as to bring out my 100 foot tape and mark it off that way. Im guessing at this points the marks are gone. However, I will have to get near that area again soon, and Ill give it one more go. Im also assuming that a bearing number given as 23519 means 235.19 Deg. from Mag North?

(or true? Sorry, its only my second week tryign to decipher the data sheets. Thanks for everyones help!

 

-Centaur

[+Centaur]

But they didnt help me find the disks. I even went so far as to bring out my 100 foot tape and mark it off that way. Im guessing at this points the marks are gone. However, I will have to get near that area again soon, and Ill give it one more go. Im also assuming that a bearing number given as 23519 means 235.19 Deg. from Mag North?

(or true? Sorry, its only my second week tryign to decipher the data sheets. Thanks for everyones help!

 

-Centaur

[survey tech]

Basically thats right, though its degrees and minutes from astronomic north, but the difference is negligible for estimation purposes.