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Can Anyone Tell Me What This Is? It's Not A Long


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I’m a newbie at this benchmarking stuff and from lurking around here for a week or so I see that I have a lot to learn. You guys take this stuff seriously! I have about a 30 min drive to work and I thought it would be fun to look at the benchmarks between home and work and maybe make a few quick finds. I got into geocaching for the kids and me to have something fun to do on the weekends and they aren’t interested in fooling around with benchmarks, at least not yet. So I thought benchmarking would be another use for my new GPSr.

So I loaded a number of cords on my route into my etrex legend and figured I’d stop and take a look if I passed one that seemed promising. So this evening on my way home I stopped at a bridge where I have a waypoint for a benchmark, LC1605, I had quickly scanned the description history and figured this was a lock. “On a bridge, above the highway…” when I got there I found this…




Now I know that this isn’t the benchmark, if I had actually read and took the time to fully think about where the bench mark was by using the description I would have kept going and had gotten a pic of the actual disk. This plaque is on the southwest end of the guardrail of the bridge. My question is what is this, and why the poor choice of acronyms? This bridge is on route 150 I can’t ever recall it being Rt. 86. I know one of you geo-gurus will be able to solve this mystery for me.

As for me, I’m going to start doing a little more book work before I do the leg work. And log some Midwest benchmarks.


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Well, offhand I would say it's just a dedication plaque, but the meaning of what each particular line means I'm not sure - but I'll take a gander. :unsure:


"station 311+45" sounds like IDOT's inventory number for this structure.


"F.A. RT. 86 SEC 113B-2" I'll guess is possibly the bid number and section for this particular project - most large highway projects are divided into sections and bid on separately - this bridge reconstruction was probably part of a larger project.


"loading HS20" - don't know


BTW - I'm also new at benchmark hunting, too. It's a very addictive hobby. :laughing:


I'm also wondering if the mark is still there, since it was set in 1976 and the bridge was reconstructed in 1977 . . . ?

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STA311+45 is 31,145 feet from the beginning of Stationing. Stationing is a method of measuring from where an engineer decides a point called ) is going to be located, which can be at the beginning of a project or maybe even the beginning of the road. In this case I dunno. Station continues forth from Station 0 to Station 1, and that is 100 feet away. 311 stations is 31,100 feet. +45 is a location 45 feet beyond the last full station. I could use the same method to describe the beginning of a Horizontal or Vertical Curve, an Intersection, a Fire Hydrant, a Catch basin, a Light Standard, a Driveway Approach, Where to paint a gore point in an on ramp or where to begin a double yellow line or end one, a street sign of any kind, and Yup, Even a Bridge.


This is a builders plate for the Bridge. It says some things that may only make sense to the Illinois department of Transportation. At the end of it is likely a bridge loading specification that the bridge is supposed to be able to meet or exceed. This plaque has nothing to do with the survey marker.


From the datasheet: IN THE TOP OF THE NORTHEAST END OF WINGWALL AT THE SOUTHEAST CORNER OF CONCRETE BRIDGE is where you will find the survey marker. This one is a reset to one that was there before on the same wingwall only 3 feet closer to the road than the one you are looking for. You may notice where it once was.


A wingwall is a concrete retaining wall that runs perpendicular to the bridge and on either side of as well as under the bridge, often on both sides of, parallel to the waterway. It is often retaining earth which is being stabilized for the area the bridge approaches are in and may also be structural components of the bridge. They often have slopes leading to and from the wingwall with the wall it self being a vertical drop off as a typical design element. It is good idea to be really careful when you find yourself in these area, do to the inherent dangers of slipping falling etc.


Be careful and good luck.



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Finding this plate got me looking on my way into work this morning and every bridge I crossed has one on it. If I was to look at the stationing for each plate I could find the beginning point?

Thanks Rob and River Lime for your input. Rob you said, “This one is a reset to one that was there before on the same wingwall only 3 feet closer to the road than the one you are looking for. You may notice where it once was.” Does that mean that PID LC1605 isn’t there and there is a new PID. Or is it the same just moved? I guess I’m asking is a “reset” a replacement of a mark where the PID is changed or just moved?

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Reset is normally a replacement for a station that's gone missing. Most of the time that means destroyed. Occasionally (rarely) you'll find a reset for a station which later turns up, but that's uncommon and an expensive duplication of work.


Reset stations commonly have the word RESET in their designation.


I sometimes see numerals added to a station name, which I believe also indicates a reset, e.g. FOO 1.



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The NMDOT is replacing a bridge over I-40 in Albuquerque, and they've destroyed FO 1126 I40 6. When I spoke with the construction engineers the first day they were tearing down the old bridge, they said they would be taking the monument and moving it to the other side of the new bridge, then resurveying it. What usually happens is that they survey and monument a brand new station nearby the old station, basing it on the old station. THEN they destroye the old station.


This way they will confuse people if they use the old mark in a new location. I have contacted the city surveying office and the state NGS rep about it, and they'll try to fix the situation, presumably by having NMDOT report a DESTROYED to the national office and then stamp RESET on the disk, or something. *sigh*


Anyways, that's how I40 6 RESET type names get in the database. I'm guessing the naming convention varies from state to state, but I haven't seen a I40 6 1 name, so I guess most people will add RESET or a number if the PID name ends in letters, and only RESET if it ends in a number.

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What I mean is that LC1605 is a replacement, or a RESET Station Mark for one that was there before it which had the same name, Q 197 and it's PID was LC1450


Station Naming Conventions were not exactly supposed to be arbitrary. As a rule of thumb, in most cases, and I say this as it was more true back in the day before GPS that it is now, If a Station has a Verbal, Phonetic Name, It was given so because it it a Horizontal control Station, (Optical Triangulation in that day), and if it has a Letter followed by a short series of usually 3 numbers and maybe other letters after that, sometimes, it was generally meant to be Vertical Control. Since GPS came along, it is not uncommon to find Stations which have been given both types of survey control, Regardless of the Naming Convention.


This particular naming convention only holds true for stations which were originally monumented by the NGS and the older names that that Agency had back in the Day, which was know as CGS or USCGS. (United Stated Coast and Geodetic Survey.) Coast Survey is now a separate arm under the National Ocean Service. The Naming conventions for all the other Agencies which set monuments varied with their policies and localities.



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Ok now I’m starting to see the light. I missed LC1450, when I did my first search I excluded any markers that were listed as not found figuring that I should at least start with ones that were there the last time someone looked. I didn’t really think about the fact that there would be duplicate entries as resets. So the rule of thumb is that every PID is different but a designator or name could be the same even though it’s a different physical marker. How about that? Am I starting to get the picture?

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I did a simple search on geocaching for Stations called Q 197. Countrywide you could say there are a few eh?


AF6123 Q 197 FL bench mark disk

BJ0972 Q 197 LA bench mark disk

BM0289 Q 197 TX bench mark disk

DJ0116 Q 197 AL bench mark disk

DL0364 Q 197 AR bench mark disk

EH0429 Q 197 MS bench mark disk

FH0853 Q 197 OK metal rod


GB0396 Q 197 KY bench mark disk

GB0945 Q 197 TN bench mark disk

GM0466 Q 197 NM bench mark disk

GX0060 Q 197 WV bench mark disk

GX3481 Q 197 RESET WV vertical control disk

JF1088 Q 197 KS bench mark disk

JV6928 Q 197 MD survey disk


KV1928 Q 197 PA bench mark disk 11/19/2004

LC1450 Q 197 IL bench mark disk

MD0950 Q 197 IN bench mark disk

MU0162 Q 197 NV bench mark disk

MW0468 Q 197 CA bench mark disk

OE1105 Q 197 NY bench mark disk

QB0668 Q 197 OR survey disk


RF0501 Q 197 ME bench mark disk

RJ0308 Q 197 MI bench mark disk

SH0521 Q 197 MN bench mark disk

SS1575 Q 197 RESET MT vertical control disk


Yes you are getting the picture. Just look back through the bench mark forum, we have already covered a lot and you can pick up on a lot more cool info on these by simply reading up in your spare time. We all have come across some doozies!


Good Luck and enjoy,



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You will note from Rob's list that the US CGS / NGS plan was to use a letter-number designation no more than once in each state. I'm sure somewhere there are exceptions, but they followed that pretty closely. Other agencies had their own numberings and there is probably more likelihood of them duplicating in a state.


In nearly every case where a mark is set for one that is getting destroyed, the new one will have RESET added to the name or else a whole new name/number designation as well as a new PID.

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Ok, so the bottom line is; it’s not as easy as it looks. I’m sure that with the seven “P”s it can make it a fun challenge that will really pay off in the end.

Thanks for all your input, I'm really excited about getting more experence and then being able to contribute as much in as I take out.


Seven Ps: Proper Prior Planning Prevents Piss Poor Performance.

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