GIS Parcel lines on topo survey?

Here is what our local county uses for disclaimers on their GIS website:

The XXX County GIS data are primarily for the support of its internal business functions and the public services it provides. The GIS data, which XXX County serves on the online mapping or distributes, are for informational purposes only and may not be suitable for other purposes or uses. It is the user’s responsibility to verify any information derived from the GIS data before making any decisions or taking any actions based on the information. XXX County is not liable for any errors in the GIS data. This includes errors of omission, commission, errors concerning the content of the data, and relative and positional accuracy of the data. Each data may have been collected at different scales, times or definitions, resulting in inconsistencies among features represented together on this map. Primary sources from which these data were compiled must be consulted for verification of information contained in the data. Parcel data was prepared for the visual representation of real property found within XXX County, and is not necessarily accurate by surveying standards. If absolute accuracy and detail is required, the deeds, plats and other related records on file with the Superior Court Clerk should be consulted. XXX County assumes no legal responsibility for this information.

There ar few other blurbs in there but this is the gist of it.

I would think you would be okay, however I would definitely call my State Board first to make sure.

Cy

I show them as part of an image in the background. My note is much shorter. In essence- THE PARCEL LINES SHOWN HEREON WERE DEVELOPED BY OTHERS FOR TAX MAPPING PURPOSES ONLY. NO CERTIFICATION IS MADE REGARDING FITNESS FOR THIS OR ANY OTHER PURPOSE.

fattiretom didn't say why the parcel data is being put on the topo. If it is for a purpose that is not-well served by the data on the map, I'm not sure disclaimers will help. It's one thing to use disclaimers to warn some unknown character that the data shouldn't be relied on for purposes other than the original purpose of the map. It's something else again to provide data that is insufficiently accurate to achieve the intended purpose of the map, and try to protect oneself with a disclaimer.

I'm thinking if it's a road topo you're going to be confined to the "corridor" just adjacent to the road bed. If the area is platted, why not just drop some linework in the drawing that reflects the platted property? If they want the parcel info also, that wouldn't be too tough.

ANYTHING would be better than perpetuating the "county's cartoons", imho.

los dos centavos de mi culo

Not sure what state you are in, but where I come from it is very common to show abutting parcel information. IE tax ID no., owners name, maybe zoning, etc. If the source is the county GIS, ok. I don't think I'd show any rear lines, but an approximation of side lines for an inch or so - no problem.

It sounds like a R/W survey, not a retracement of individual lots. That would really get the city in trouble from the private sector.

I would likely even skip the disclaimer because in essence it is just for your warm & fuzzy, and gives you no real protection. You're regulated/governed by laws for the survey work, and your scope for the court.

good luck

We have a municipal client that wants us to do a roadway topo survey and then lay in county GIS parcel data

Sometimes the parcel lines can be so bad there is absolutely no point using them, other times they are close, I would hesitate without some real world information. Disclaimers can get you in trouble.

Whenever I use GIS parcel lines on any of my design surveys, I'll use a broken line type and light line weight for them and include in the legend the source of the data, noting they are for informational purposes only and are not surveyed. The surveyed lines get a solid line type and heavier line weight. Note my finished product is only used in house and doesn't get my stamp. I nearly always have some kind of control to orient to with GIS lines and if it's too wonky, I leave it out.

Your call.

Part of the work flow on many road jobs is the preparation of a base map for parcel identification. The entity governing the project needs a starting point for research. A composite map of the approximate route and tax parcels is perfect. If the lines are part of a geo-referenced image (as opposed to ACAD line work) they can't be grabbed and layer changed by accident. The note is just that, a note saying what the lines are. It would take a room full of creative attorneys to turn that around. I agree liability abounds in this day and age but at some point I have to say I've done enough... my .02

> ...It's one thing to use disclaimers to warn some unknown character that the data shouldn't be relied on for purposes other than the original purpose of the map. It's something else again to provide data that is insufficiently accurate to achieve the intended purpose of the map, and try to protect oneself with a disclaimer.

Absolute :good:

I would check with your E&O carrier...

I ran into a similar situation with our GIS manager a few years ago. Our parcel lines on our GIS imagery are anywhere from 5 -20 feet off the actual boundary line location depending on the subdivision. They solve this dilemma with –
These maps may be generalized and may not reflect current conditions. Maps obtained using this site are for illustrative purposes only and are not designed to assist in navigation or as a substitute for legal survey. The coordinates displayed do not represent legal parcel corners and/or boundaries and they cannot be used for establishment of or in lieu of legal land survey boundaries for property or parcels thereof. This map may contain cartographic errors and omissions.

I have had several interesting and sometimes heated discussions with irate landowners that have been toting copies of the GIS map; they insist I am setting their corner in the wrong spot “according to the government”.
The government spends about $100,000+ every few years on new imagery for the GIS site but they refuse to spend money to get a surveyor to proof any of the lines. After several complaints they purchased some GPS equipment and went out and surveyed several subdivision corners to true up their product. After they had surveyed it they started using the map to find building and zoning violations and issue citations. The head of the department even went out and surveyed some private property and delivered his opinion as to the location of someone’s lost property corner. A local surveyor (not me) reported them to the board and the board issued them a warning. During this process I did a large topo survey for them and they asked me to include the current GIS line work in that topo. Sometime later I learned that they had taken the data and shifted the line work to the correct position I had provided in my topo product and now when they have questions about the GIS accuracy anywhere within a 10 block radius of this subdivision they respond by saying “they had a surveyor correct the GIS map".

Bottom line, - I am very sorry I allowed them to include this data without getting paid for all the trouble it is to me and the public and will continue to be in the future.

In our state, we have a statute that says, in part:
"(2) All documents, plats, and reports resulting from the practice of land surveying shall be identified with and bear the seal or exact copy thereof, signature, and date of signature of the land surveyor in responsible charge."

I identify documents (plats or reports) that are not resulting from the practice of land surveying, and make a point to not sign and seal those. I think that it would be just as wrong to stamp a document that does not constitute a result of a land survey as it would be to "not stamp" a document that was.

I don't know if your state has a similar law, and I don't know if what you are proposing to do would be considered "a result from the practice of land surveying". (I would be concerned that the "topo" would be considered a part of land surveying, but maybe not, if it doesn't tie to property lines. That would be per your state statutes.)

Anyway, what the product is should be made very clear. I would be concerned with stamping it if I am showing approximate property lines that are not surveyed in. The fact that they are getting it from a land surveyor would make some people want to say, "this is where a land surveyor put my property lines".

It would be nice if it could be presented as a map provided by a non-land surveyor who has the disclaimers on it that it is not prepared by a land surveyor and the lines are for the purposes (as some have described above).

Sorry for the bit of rambling here....just kind of thinking while I type.

Part of the work flow on many road jobs is the preparation of a base map for parcel identification. The entity governing the project needs a starting point for research. A composite map of the approximate route and tax parcels is perfect.

For sure preliminary maps need something rough, but for final documents not so much, kinda depends what they are used for.;-)

I do it all the time on public works projects.

Generally my clients will want the topo and utility survey with a GIS property line mosaic for preliminary design work then we go back and perform boundary surveys and prepare easement exhibits or plats for takings after they have determined which specific properties are impacted.

Just wrapped one up for Phase One of this project and am gearing up for Phase Two

I think Jim in AZ knows this similar story. But a good size somewhat rural city was building their GIS data base, but they neglected to include the long standing city surveyor for control and assistance. Then the GIS guys got those handy little GIS grade data collectors and went to town, maybe even a real live rover, thinking they knew what they were doing.

When the city surveyor caught wind, there was some head bumping and chest thumping. In essence the GIS dept was "surveying", per AZ statute because they were establishing and mapping property lines (even if it was the R/W lines), and not under the supervision of a RLS. He was right, so he filed a claim with the state BTR against the city.

Took a few years but I think the city got their hand slapped, a fine, and told "don't do that anymore". The city surveyor retired, along with the city engineer. Forced retirements? Dunno

I think this problem is more common than most folks realize.

I think folks might be over thinking this. The work product requested is essentially an engineering topo plan. Any PE could provide this deliverable. As soon as someone puts a label on any of the parcel lines, THAT is when they are representing them as parcel boundary lines.

No label. No liability.

> We have a municipal client that wants us to do a roadway topo survey and then lay in county GIS parcel data. They have no problem with me putting some strongly worded notes on the map about where the data came from, that they have not been surveyed, and should not be relied upon, etc.

I think that my first question would be what the intended use of the map would be. I mean, are you going to be actually locating the right-of-way lines by survey and then overlaying GIS parcel data that obviously won't match what was found on the ground?

My own view is that if the the potential for misuse of the data is obvious and the necessary disclaimer boils down to: "Don't think this map means anything because it doesn't", then something needs to be rethought.

"V"

And there is no longer a City Surveyor position...