Ok, first off, I've never worked with a GPS system, although I am familiar with the concepts involved with lat/lon. Background--I'm looking for the end of a sewer lateral. The contractor who did the sitework did all their layout using a GPS system. Their sewer crews installed the laterals, and marked the ends with a piece of 2x4, generally left sticking up out of the ground 2'-4'. Sometimes they survived, but sometimes their own grading crew knocked them over, and if they didn't get them, the gas company's contractor did. In cases where the 2x4 no longer sticks out of the ground, we have a set of site plans that's been pretty accurate. We can scale the location off the plans to the curb, and the water curb box, or the nearest manhole, etc, scratch around with the excavator for a few minutes and find what's left of the top of the 2x4, and go down from there. Worst case so far has been one where I had to go 4 feet down to see evidence of the trench, and chase it back to find the 2x4 almost directly beneath the gas curb box. This time, I've dug five feet deep, and about 10x20 feet wide, and found nothing. I recall a conversation with somebody, either their superintendent or an inspector, where I was told they have as-built GPS locations for the end of all their laterals. I passed that along to the home builder's superintendent, and asked if he could get that information for this lot. Last night, I got a text from him with the numbers, but I can't make sense of them according to anything I know about lat/lon. What I got was " N402228.8 E1364164.8 ". Now, in this part of western PA, we're around N40, WEST 80. Obviously, those numbers aren't in degrees, minutes, seconds, but according to my understanding, they aren't even a valid version of decimal degrees, which would look more like N40.xxxx W80.xxxx . Further, if we assume that it's supposed to be "N40 decimal point 22288", that's about 14 miles south of where I'm looking. The East-West question, I dunno. E 136.xxxx puts me in the wrong hemisphere... :beatsme I'm certainly open to the possibility that I don't know enough about it to make use of the info as I've received it, but looking around the internet hasn't shown me anything that makes me think I'm that wrong. Anybody got any good ideas? Thanks in advance.
I have used a similar coordinate system in the mining business. You start at a reference point generally labeled something like 1000N and 1000E . So coordinate 1500N and 750E is 500 units North and 250 units West of the reference point. Think grid with the reference point generally in the center of the drawing. This system usually included elevation referenced to sea level as we needed surface coordinates for drilling and subsurface for mining. The North and East coordinates are usually based on True North. The key is finding at least one labeled point and preferably two labeled points for checking purposes. A compass with true north corrected readings might be useful too. No GPS needed, just a suitable measuring device. The GPS would be easier if you can convert to a grid coordinate system and label your reference point correctly.
Thanks. I appreciate the reply. It was suggested to me that the coordinates might be "Northing and Easting" coordinates.I hadn't heard of that before, but the internet is a wonderful thing. ( http://en.wikipedia.org/wiki/Easting_and_northing ) What you're describing sounds like it works on the same principle. The trouble is that, just having those two numbers doesn't really do me any good if I haven't been provided with the format being used. (I learned more about that here: http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system#Locating_a_position_using_UTM_coordinates , and here: http://www.earthpoint.us/Convert.aspx ) Google Earth has an option to show locations in UTM, but when I look at the project there, the numbers don't even come close to what I was given. (I understand that it's also possible that they could even refer to some grid peculiar to the data itself, as opposed to something in common usage that I might find through internet research. That sounds like what you're referring to as well.) :beatsme <--(I have a feeling I'm going to be using that smiley a lot if this discussion continues...)
Those are apparently survey quality coordinates that can be converted here. http://www.earthpoint.us/Convert.aspx which will show you this when you put those coordinates in. Calculated Values - based on Degrees Lat Long to seven decimal places. Position Type Lat Lon Degrees Lat Long 40.3746667°, 136.7013333° Degrees Minutes 40°22.48000', 136°42.08000' Degrees Minutes Seconds 40°22'28.8000", 136°42'04.8000" UTM 53T 644431mE 4470732mN MGRS 53TPE4443170732 Grid North 1.1° Maidenhead PN80II49DW80 GEOREF XJBL42082248 Keep in mind what it took me forever to remember: when looking for eastings (or westings) in the northern hemisphere; enter a negative mark ahead of the longitude heading or it will direct to other side of the world. Since the DOD has turned the SA switches on all the milsats over the US, if you have access to a handheld GPS, you can enter those coordinates and use the GOTO function and it should put you right on top of it.
well, as I look at your coords, it appears that they are survey northings and there is still a conversion but they are found at corpscon, and datum, zone and state are needed. It does pin it down to the nearest mm though. May be some more help here: http://www.pasda.psu.edu/mapping/default.asp
Thanks. I was becoming pretty sure that something more than just those numbers was needed. As it turns out, the solution was pretty simple, although I still can't say I have the answer to the questions about how to decipher the coordinates. I kicked it back to the builder's superintendent, and suggested he call his survey company, and ask them if they could make sense of them. I also suggested that since they had laid out the house, and knew the location of its corners, maybe all they'd need to do was sit there and figure out how far the given coordinates were from the front right and left corners of the house. Obviously, they knew what they needed to know about them. I got the numbers I needed today, in good old feet and inches, and using my trusty tape measure, located the spot. I had to dig down almost six feet, but I found the broken off tip of the 2x4, under a rock, right where they said it should be. Next time, I'll dig deeper before I give up. And the next time I see the survey crew out on the site, you can be sure I'll be asking for some more education on the subject. (Although I must say, I now know a whole lot more about northing and easting than I did on Monday...)
Just read through the thread and that was going to be my suggestion - kick it back up the ladder.