Disclaimers found on NYC Maps

Below, I have included a list of the different disclaimers found on Manhattan documentation and Maps and presented my evaluations of them.

Found on Digital Tax Maps
"The maps and information presented are for information purposes only. The City of New York Department of Finance is not responsible for errors, omissions, or geographic accuracy on these digital maps. The Geographic Information System (GIS) information presented should not be used for boundary lines or location and should not be used as a substitute for engineer drawings or surveys. Any use of this map for conveyances of property or any other legal proceeding is at the sole risk of the parties".

Comment: It is common knowledge, to Surveyors, that tax maps are based upon a paraphrase of the deed and that they do not represent property lines.

Found on Traverse Maps
"This drawing is not an official public document nor has it been approved by the board of estimate for any purpose whatsoever. It is merely a computation sheet which has not been checked, and the City of New York assumes no responsibility for the accuracy thereof".

Comment: These are Maps showing bearing and distances (Despite statements to the contrary that computations have been checked)

Found on Borough Survey
"This drawing is not the official City Map, nor has it been approved by the board of board of estimate for any purpose whatsoever. It is merely a computation sheet which has not been checked, and the City of New York assumes no responsibility for the accuracy thereof".

Maps showing corner coordinates, monuments, Street dimensions, Bearings

Comment: It appears clear that it may not be safe to use any of the above Maps etc... It would appear that it would be unlikely for someone to trust any of these maps. It would also represent a great deal of effort for a Surveyor to generate values from them or to utilize the monuments set even if they were recoverable. What is not clear to me is why it is mandatory that Surveyors rely upon this information or any information derived from it.

Found on Section Maps
There are 2 different disclaimers set upon these Section Maps

The first disclaimer states: "The City of New York Assumes no Responsibility for the Accuracy of this Map".

The second disclaimer states: Notice: "This map has been generated from information obtained from several sources over an indeterminate period of time. Therefore the information shown on this print may or may not portray the lines and grades of city Streets at any specific period of time".

Maps showing Block dimensions , distances to curbs, street widths, legal grades.

Comment: This particular disclaimer is not clear and is deliberately misleading. It gives no indication that the information shown thereon, nearly never accurately portrays property lines or that it is derived from the Traverse Maps & Borough Survey Maps, which have been rejected by the board of estimate for any purpose whatsoever. It avoids the issue that the exact position of Curbs and Street Widths are inaccurate and approximate at best. Furthermore, they are known to be meaningless to property lines and set in position by laymen with no concern for property lines. I believe that since the monuments are not available it is these Section Maps that are primarily being relied upon.

Despite the fact that the disclaimer states that "the information shown on this print may or may not portray the lines and grades of city Streets at any specific period of time", it does appear clear that any uncertainty regarding time, can easily be verified by a Street Report, which easily determines the time since any roadway was changed. It would appear that if there was no change in Street Width since the monuments were set that the Map would be safe to rely upon. It is common knowledge that the City no longer provides Legal Grades.

Considering the heavy encouragements and demand to use the Map, it certainly appears likely that, after the possible flaw is identified, a person could rely upon the simple dimensions found and remaining on the map. Common sense tells us that something must be correct.

The Maps appear to offer a simple and clear representation of exact values. Dimensions appear very clear, mathematically correct, and trustworthy. That, in combination with the demand to use it, leads a Surveyor to believe that many of the lines must be correct and the only need is to rely solely upon the property line to curb dimension provided and the length & width of the block to be accurate. Such an assumption would not be safe.

Please do not make the mistake of assuming that the errors generated will be minor. Typically they are compounded. An actual example that happened to a Surveyor new to the area Occurred when he set at one intersection and measured to the curbs and corners of the buildings assuming that they were at the intersections of property lines. He did the same at the next block and thereby established his line. He then turned the published angle and extended his line about 1,000 feet to the job site. His error was in excess of 14 feet.

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