Very Unusual Disk

[+kc8hnz]

I found a really wierd mark today. It is set into a bridge down the road from my house, and I stumbled upon it while I was walking. Thing about it, as you can see, there is no markings on it at all! And of course it's not listed in the database so I'm assuming its probelly a local or state DOT mark, but from the lack of ID who knows. Has anyone else seen one like this before?

 

 

[+jeff35080]

Some states, counties and muncipalites place blank disks on all new bridges, should they ever be needed for future marks.

[+GEO*Trailblazer 1]

Not for sure but looks like a Monel Rivet?

Monel Rivet

Edited February 18, 2004 by GEO*Trailblazer 1

[+kc8hnz]

Not sure what a monel rivet is, but this definattly is a disk, about 2 1/2 inches in diameter. It does seam to be more curved upward then a standard disk, this help any?

[+GEO*Trailblazer 1]

See link above post added after your answer.

[+kc8hnz]

Thats it! The round headed on at the top of the 'riviets' list. So, then maybe this isn't a mark at all? Its only on the one corner of the bridge, though, and I have heard of rivets being used before.

[+GEO*Trailblazer 1]

Yes they are the smaller ones used by the RailRoads in the 1800's.

I have found a few of them too.

[Z15]

Often times bridges have reference marks installed at the time it is built. In Michigan they used 5/8 inch round bronze pins in each of the abutments (total of 4). This was a common practice many years back and although this was done ny the contractors, it was never adopted or used a as reference point by anyone. Also, we often used anything we could find to set a control point in a bridge. A bolt, nail, you name it, if we thought it was going to last,we would use it. Often just went to the local county road dept and see what they had that we could use.

 

What is the diameter of the object? Judging from the photo, it was set at the time the bridge/culvert was built and may be what I said as a plan control point but something never used for anything. They were just following a standard plan spec.

 

I have seen very similar marks before with no legend cast on them or any stamping but a point of reference (dot) in the center.

RL0051_U.S. NATIONAL GRID SPATIAL ADDRESS: 16TCS889792(NAD 83)

RL0051_MARKER: DB = BENCH MARK DISK

RL0051_SETTING: 36 = BUILDING

RL0051_MAGNETIC: O = OTHER; SEE DESCRIPTION

RL0051_STABILITY: B = PROBABLY HOLD POSITION/ELEVATION WELL

RL0051_SATELLITE: THE SITE LOCATION WAS REPORTED AS NOT SUITABLE FOR

RL0051+SATELLITE: SATELLITE OBSERVATIONS - September 10, 1996

RL0051

RL0051  HISTORY    - Date    Condition        Report By

RL0051  HISTORY    - 1948    MONUMENTED      CGS

RL0051  HISTORY    - 19951015 POOR            USPSQD

RL0051  HISTORY    - 19960910 GOOD            MIDT

RL0051

RL0051                          STATION DESCRIPTION

RL0051

RL0051'DESCRIBED BY COAST AND GEODETIC SURVEY 1948

RL0051'AT L ANSE.

RL0051'AT L ANSE, SET VERTICALLY IN THE NORTHEAST WALL AT THE NORTH

RL0051'CORNER OF THE COMMERCIAL BANK BUILDING, 3 1/2 FEET SOUTHEAST OF

RL0051'THE NORTH CORNER AND 4 1/2 FEET ABOVE THE SIDE WALK.  A 3-INCH

RL0051'BRONZE DISK.

RL0051

RL0051                          STATION RECOVERY (1995)

RL0051

RL0051'RECOVERY NOTE BY US POWER SQUADRON 1995

RL0051'MARK RECOVERED IN POOR CONDITION.

RL0051

RL0051                          STATION RECOVERY (1996)

RL0051

RL0051'RECOVERY NOTE BY MICHIGAN DEPARTMENT OF TRANSPORTATION 1996 (BRT)

RL0051'AT LANSE, IN THE COMMERCIAL BANK BUILDING AT THE CORNER OF BROAD AND

RL0051'MAIN STREETS TO REACH FROM THE POST OFFICE IN LANSE FOLLOW MAIN STREET

RL0051'WEST ONE BLOCK TO THE FLASHING TRAFFIC LIGHT AND FOUR WAY STOP.  BANK

RL0051'IS IN THE SOUTHWEST QUADRANT OF THE INTERSECTION STATION IS 1.07 M

RL0051'(3.51 FT) SOUTHEAST OF THE NORTH CORNER AND FACING BROAD STREET, AND

RL0051'1.37 M (4.49 FT) ABOVE THE SIDEWALK.  A 7.62 CM BRONZE DISK WITHOUT

RL0051'ANY MARKINGS SET VERTICALLY.

Edited February 18, 2004 by elcamino

[+Spoo]

I suspect that this may be a surveyors mark for the bridge itself. Something to aline his plumb-bob on his transit with. This allows him to measure for movement of the bridge itself. Ships have similar survey pins on them.

[tori d]

A bridge near my home with a benchmark at each end is being torn down to be replaced by a new one. When I asked the construction supervisor what would happen to the disks, he told me they would be replaced with new blank disks.

The contractor doesn't mark the new disks, but leaves them for the highway department ( or USGS,etc.) who might mark them or maybe not. They could remain blank for the life of the bridge.

[Mark from Careywood]

It happens, sometimes, that in the world of transportation departments, blank survey markers get set, intended to be stamped later by the responsible survey charged with that task, but end up not getting stamped for a variety of reasons.

 

Such as:

1) Lack of money.

2) A squabble between the transportation department and the contract surveyor (assuming one was used).

3) It was forgotten.

4) And who knows what else?

 

I have personally witnessed No. 2 before, and I can assure it is most irritating to those of us who need to use the monument.

Edited February 29, 2004 by Mark from Careywood

[Mark from Careywood]

Addendum to my previous post.

 

Also in the case of this benchmark, it might be that it was never intended to be stamped. If you wanted its elevation data you would have to contact the transportation department to get it.

 

By the way, it looks like a terrible place to have to set a tripod. I don't see a surveyor trying to occupy it. (Unless the party chief wants to screw with his instrument man.)

 

*******************************************

Sorry for the double post. I just realized I could've edited my previous post.

Edited February 29, 2004 by Mark from Careywood

[Z15]

Thats assuming it a survey mark to begin with.

[+DustyJacket]

There is one similar to that - a disk with a dot in the center, although this one has some stampings in it.

 

 

It is a few hundred feet away from an NGS disk that I found, protected by its own guardrail, and is mentioned in the NGS data sheet for their mark.

 

It is a city disk. It is on a square mound and has line-of-sight to the East, whereas the NGS disk is blocked by the mound and has line-of-sight to the West.