mloser

GH55 is correct--the mileposts start at some specific point, often the headquarters location of the railroad. For instance, the PRR started with Mile 0 in Philadelphia, so Harrisburg, where I spent a lot of time watching trains, sat at about mile 100. Surprisingly this has not changed, so milepost 113, mentioned in KW0880, set in 1941, is STILL mile 113, although the original cast iron post has been augmented by a large reflective 113 sign. At other locations I have seen the cast iron numbers ground off these posts and replaced with different ones (I think Amtrak did this with the markers from Phila to Harrisburg. They may have changed their zero mile from Phila to NYC or DC). I located a track chart showing that area and am not sure how it would help me if the railroad-related landmarks were gone. Take a look at PRR Track Chart View to Banks, but be aware that it is a big file. You can see the milpost lines on the chart but the level of detail isn't enough to pin down a benchmark closer than a GPSr would. Few track charts that I have ever see (of the PRR anyway) ever showed more than a schematic view of the tracks. The only other mile marker I have found was LY0259 and was marked 73, which is most likely the mileage from Newark or NYC along the NYO&W. This marker is along an abandoned right of way that was not made into a trail, and there was probably no effort to clean up the right of way after the rails were taken up for scrap. I found a number of PRR track charts online but was unable to find one from the Carlisle area, although I may have been searching for the wrong thing. I tried Carlisle, Chambersburg, PRR and NC (Northern Central).

Art, Sorry to hear you had trouble finding marks along the old railroads. Without the landmarks it is very difficult to locate marks, especially since some of them are just rivets in the Central PA area. I have been a railfan all my life and haven't found anything directly railroad related that would help with benchmark hunting on old, or current, railroad beds. Along the old PRR from Phila to the west the mileposts remain, but have been renumbered. Still, that makes it much easier to locate a milepost if it is near your mark, even if the number is incorrect. The problem is that the railroad is very busy and that Norfolk Southern is not accomodating to trespassers. Amtrak police are almost non-existent so hunting on what is derogatorily called the "Harrisburg branch" is safer from that standpoint, but the trains often top 70 mph and can be very quiet, so pick your poison. As for abandoned railbeds, I have had no luck finding mileposts and have resorted to simple visual search methods. A metal detector helps, but mine is small and weak so I use it only when I strongly suspect the mark is in the immediate vicinity. For instance, I have looked for KW0469 on two separate occasions, and measured as carefully as I could but if the mark exists it is under ballast and dirt that was pushed along the bank years ago. I even prodded and dug in a few spots and came up empty handed. I have also searched for KW0809twice with no luck at all, as it is also under ballast. While the mileposts are usually gone, the bridges are often still numbered, but the numbers are on the sides so it would take a dip in a creek to see it. One resource I use, that I am assuming you also use, is topo maps. If the mark is on the map the location of the X is usually more accurate than the scaled coords. Still, as you stand on the old roadbed looking at 100 feet of rock outcrop covered in dirt and cinders, the task does look a bit hopeless. And often it is!

gnbrotz and I teamed up last year for a marathon day. I found that having two brains, four eyes, two sets of hands helped tremendously in making the process more efficient. The two of us were able to combine our thoughts about the location of harder to find marks, help measure, keep an eye on the GPSr and datasheets while driving, etc. That said, and although I enjoyed the day a lot, I tend to WANT to hunt alone. It is a way to get out and about and use my mind while being semi-active. I really enjoy doing it by myself. Most of the time. Matt Edited for spelling and some clarity.

John, I would never say not to go after marks not previously found, as I take great joy in looking for and locating such marks. The best of course are those not found by "official" agencies. What makes MZ1572 unique is the detail in the recovery about the search for the mark, proving that a major attempt was made to locate it. Often there is no descriptive text about the effort at all. Since you are looking for another mark in the area I say go for it! It would be a great find. Matt

Wait a minute! AE8962 has been marked as destroyed due to a new floow so there is no sense even looking for it.

Two things: Maybe masonry means tile in this instance. I didn't get a lot of sleep last night and my brain thought masonry=concrete, which is a foolish assumption. The datasheet doesn't say concrete so it probably isn't concrete. The flooring might have been replaced, or simply worn down, although a good chiseled mark would be pretty deep and noticable. Are you sure you measured in the right direction? The eccentric is on line with a TV tower so if that tower still exists you could stand at the mark and look for it (my guess and hope is that the tower would be visible through a window) and that would give you the direction to the chiseled cross. The tower is at 7 deg 33 min 50.6 sec from the station. Your magnetic declination is +1.365 degrees which means you can almost ignore it, but if you want to use it you will find the tower at about 6 deg. If I am looking at your picture correctly and your left arm would be North, which seems to put your GPS about where I would expect the cross to be. I have found eccentrics to be difficult to locate in some cases. They are often set as temporary marks when a station is hard to occupy or the sight lines are not good from the main station. Then an eccentric is set up where sight lines are good and that new station is occupied. If the accuracy of the survey requires it the eccentric will be measured to a high order, and submitted to the NGS, if the surveyor bothers. (Actual surveyors may want to chime in with more info on this or harsh corrections if I am wrong). Yes, I would mark the two NGS destroyed marks as destroyed on GC, if for no other reason than to help complete the area I am looking in. I had a similar instance of a mark I had looked for twice and not found and suddenly it appeared as destroyed in the NGS database. I marked it destroyed at GC with a note saying it was marked destroyed at NGS. The higher level of proof exists at NGS so I am confident it is truly gone.

I think the eccentric is gone. The datasheet notes a masonry floor and there is tile there now. Note that the Snelling mark itself is in concrete and they have preserved the floor around it. If the tile had been there when the mark was set they would have set it in the tile floor.

You DID read the 1934 recovery didn't you? I don't think the azimuths will be your problem.

Art, I wasn't speculating about why the description was changed, just about the numbers on it. You might try emailing Casey or Deb though. They might have a record of the change offline. Matt

I think 199 is the elevation, which is stated as 197.16 on the datasheet but may well have been 199 using another datum when the disk was set and converted to NAD83 at some point. I have seen a number of disks with elevations on them that are close but not quite at the datasheet's elevation and have always attributed it to change in datum(s). My guess is that the disk is a USE disk, and has "9" above the center and then "199" below the center. KW1060 296 USGS is an example but the pic I took is awful. Those more learned in these matters may chime in with details and corrections. Matt Edited to add poor example

I think this thread just needs to end, regardless of what has been posted and what the content. It no longer has any relation to the topic and has become a massive flame.

Harry, I am solidly with the "dig deeper" crowd. I would think that you will find the top of a standard concrete monument with a disk embedded in it, just like most separately monumented disks. It doesn't sound like it will be a "disk on a post" like some recent settings. Matt

Even a bit north of you in PA it has been an oppressive summer. I went out hunting yesterday but the humidity got the best of me and I was wilted in short order. My end result was one find and one drive-by find, and 3 DNFs that need looked at again when vegetation recedes to be certain they are actual DNFs. Summer is a Catch-22--you want to go out when the temps are nice but the undergrowth makes searching a hundred times more difficult. I have found that I do my most enjoyable and successful hunting in early spring, when temps are high enough that I don't freeze but the spring plant growth has just started.

KW0535 (PA) Another style of PA Dept of Highways disk. This one has PSDH on it, for PA State Dept of Highways, I imagine. Odd thing is that this disk was monumented the same year as KW0534 and the disks are very different. They were probably set when the bridges were built and only surveyed and stamped in 1942.

KW0534 Here is a different style Pennsylvania Department of Highways from 1942, listed as Pennsylvania State Department of Highways.

This show was an entire hour on the bridge and was well done, except they didn't mention surveying and benchmarks enough! Or at all really! I meant my copy. I bought it on a whim and doubt I will ever really read it in detail. I would rather someone who would enjoy it have it then keep it on my shelf forever, even though I do seem to collect books just for the sake of having them. Matt

I have started to believe that many many tower recoveries are wrong, including some of mine. I first noticed this when I went to the actual trouble to visit a tower in the Harrisburg, PA area because there was a tri-station at the base of it. While there I noticed that although the tower appeared to be in the same place as described, there was definite evidence of different support cable anchors near the current ones. A check of the tower database confirmed that this tower went up much later than the one described. The real question is--if the tower is in the SAME SPOT, is it still usable as an intersection point? I didn't think to prove or disprove this at the time, but it has led me to recover fewer antennas since I am never sure if they are in the same spot and reaching them is often very hard. There are previous discussions about this subject on the board for those who want some deeper opinions. Matt

Mike, After all this talk about the bridge, there was a special on it on the History channel last night (July 5th). They even showed, briefly, one of the observation platforms. Are you interested in purchasing that book? Matt

Here is another to add. Greg Rotz and I found this one last year. JV6075

R_C, Yes, it is usable. As stated in other postings the main station is the one that will be used for surveying purposes. Only it and the azi mark have PIDs (in this case... some RMs have their own PID so are usable for vertical surveying), so they are the only stations that can be used for surveying. The RMs are there to help locate the station and to recreate it if it is lost. If the station is undisturbed it is usable. Your references to the RMs in the recovery are good--you put in what you did and what you found. That allows someone looking for the mark(s) in the future to use your research if they want to locate them, or gives them some reasoning why the stations cannot be found. Matt

It is called Miracle Bridge at Mackinac, by David B. Steinman. I picked it up at a Boston bookseller last year for $10. It does mention a 1934 attempt to build a bridge but no work was done at all, so your theory about wrong dates is most likely correct.

The book says it was the G. Edwin Pidcock Company of Allentown, PA that did all the surveying. It describes 8 land based and 6 sea based towers. The sea based towers are of little interest, but the land based towers have some history--three were based on established triangulation stations, "some of them more than one hundred years old." There were two "on the Mackinaw City side, one at the starting point of the bridge, and the other exactly 10,405.038 feet west of that point. Three were located on the St. Ignace mainland proper, two of these being situated along U.S. 2: 10,858.443 feet apart, and used as the baseline for the triangulating operations. Two additional land-based stations were established on the St. Ignace causeway, one at each end. The eighth land-based surveying point was established on Green Island..." By looking at the decriptions I am thinking that QK0251 is one of the eight, and fairly certain that QK0740 is one of the older-than-100-year ones. It was "not found" by the Power Squadron in 1995 but they may not have read that it is 18 inches underground. QK0272 is along US 2, QK0728 is the only mark on Green Island. QK0779 appears to be another old one, reset. Maybe the two you show the datasheets for, QK0249 and QK0733, are the other two. By downloading the NGS datasheets based on the center of the bridge you could probably find all the ones set, or used in 1954 and get a good handle on which were used for the bridge construction. A little side note. While looking for the 1954 marks I found a few set in 1934 that say they will be destoyed when the bridge is constructed. This goes back to an earlier attempt to build the bridge. The Mackinac Straits Bridge Authority was given the right to investigate the feasibility of building a bridge (and to actually build it) in 1934. Obviously one of their early tasks was to survey locations for the structure. Because this version of the bridge was never built some of these marks, such as QK0250, may still remain (although that is a bad example because it appears to lie right in the center of the highway).

Pioneer and clumsy Tiff, I am not sure what you found, but it was neither of the marks you listed. Both were on top of a Navy building of some sort and were tacks in the roof. They were both considered lost a long time ago, as one might think would happen to a tack on a roof since 1921 and 1933. Making them even tougher to find is that the building was torn down. A 1963 note on both of the stations you reference says the building was destroyed. What you seem to have found is reference mark 2 of station RADIO 3, which logically followed RADIO and RADIO 2 after they were not recovered. Possibly in 1959 the CA State Lands Comm put in a triangulation station to replace the two previous stations but never submitted it to the NGS. You seem to have found one of the thousands (millions?) of benchmarks that exist but are not in the NGS database. The CA Land Comm might have information on it.

Welcome! I figured I should say "hi" too. My name is Matt and I hunt in the south central PA area, with forays to other areas as I can manage. I tend to be more quiet than some on this forum but you will see posts from me at times. I have been a very active benchmarker and hit my 500th mark after a little more than a year hunting. I have been going pretty slow this summer because of other commitments, but will get back into as soon as I can. Keep looking at the board to learn a lot about benchmark hunting. There are a lot of knowledgable people here, and even a few surveyors, who often chime in with some real world style advice. And remember to have fun! Matt

I have had a few where the reference marks were very difficult. Never had a car in the way, although I do tend to park my own car where I need to measure sometimes. I gave up on one reference because of the prettiest, shiniest poison ivy I have ever seen. I haven't been back in winter yet to pick that one up. I have had to measure around thorn bushes, through trees, etc, which makes measurements very difficult. After 2 1/2 hours of searching I finally gave up on a reference mark for KW2118. I had to measure through a group of trees, across a pile of rocks, and it was more than my tape could measure directely. I am sure the disk was covered by years of leaves and dirt and simply couldn't find it, despite using a small metal detector and shoveling the dirt off every boulder I located.