Surveying, Mapping and GIS

The Pittsburgh Tribune-Review reports a sticky lawsuit over an eminent domain case, where the South Allegheny School District had taken a man's land by eminent domain, and paid the wrong family- based on errors in the tax assessment system.

Evidently, there were misnumbered lots on a plat, compounded by a propagation of error when the county re-drew the map. As a result, the tax map system had the wrong owners shown, who were apparently compensated $80,000 by the district.

The county is planning to go to a GIS-based system, but the question and doubt remains as to how many faulty property lines and how much erroneous ownership data is propagated from map to map, and carried over into GIS-based tax assessment systems.

Typically, from what I have seen, tax mapping GIS systems are often digitized/rubbersheeted from old hand-drawn maps, or 1"=400' scale or worse. Additionally, much of the work, whether manual or GIS-based, is performed without the benefit of thorough analysis, input or research of deeds, ownership and boundary data.

It's disturbing on many levels- first the School District should have done its due dilligence to verify the parcel and its ownership. Also, Cadastral GIS systems tend to be a pet peeve of mine- It's another example of where domain expertise and GIS expertise need to come together, lest they simply become a system to generate pretty maps that only get people in trouble.