GIS and Surveying: Impacts and Opportunities

Transcription

1 GIS and Surveying: Impacts and Opportunities Dr. Gary Jeffress, R.P.L.S. Professor of Geographic Information Science Geographic Information Science Program Department of Computing and Mathematical Sciences Texas A&M University-Corpus Christi 6300 Ocean Drive Corpus Christi, Texas Phone (361) Fax (361) Abstract The demand for accurate spatial data with known error budgets is increasing with the increased use of GIS throughout all sectors of the economy. GIS users are beginning to see that with increased reliance on GIS data and information there is a corresponding increase in the risk and liability if the data is of unknown or dubious accuracy. This paper argues that the Surveying Profession has the education, skills, legal understanding, and experience in minimizing these risks and liabilities. But are there enough surveyors to take on the extra demand for these new uses of spatial data? Evidence is emerging that the number of surveying professionals is declining at the same time demand for surveying services is increasing. The shortage of professional surveyors presents challenges and opportunities for both GIS and surveying professionals. Traditional Role of Surveyors The surveying profession is one of the many professions that claim to be the second oldest profession. There is much historical evidence dating as far back as 5000 BC of surveyor s works to demarcate land and property boundaries. Clay tablets from 5000 BC Persia clearly show mapped land parcel boundaries and 2000 BC Egyptian hieroglyphics show the rope stretchers laying out boundaries that had to be reconstructed on an annual basis after the floodwaters of the Nile River receded (Davis, 1998.) Indeed these records do show the early attempts of the key role of the surveying profession of accurately locating, measuring, and marking the artificial boundaries that define the limits of jurisdiction or land ownership and measuring the topographical features of the earth. The surveying profession, however, cannot claim sole professional lineage to the authors of these ancient documents. The concept of learned professional disciplines is a very recent phenomenon. Those who had the education and knowledge to undertake the measurement of land in historic times, probably were the educated elite that could also turn their knowledge to engineering, architecture, geography, mathematics, and physics with equal skill using the limits of scientific understanding of the day. This idea is also born out in more recent history in none other than George Washington, the first President of the United States, whose first means of self-sufficiency was that of a land surveyor.

2 Of course Washington later went on to use his education and skills in war, politics, law, and city planning. Nonetheless, the traditional role of the professional surveyor is to research, measure, locate, and define the legal limits to land ownership and jurisdiction just as George Washington did from the age of 15 to 24 years (Bedini, 2000). As societies became more complex, so did the demands upon the surveying profession. Surveyors have traditionally had similar working skills to those of the civil engineer and based on applied mathematics, particularly trigonometry, geometry, and coordinate geometry. Many surveying education programs were born out of civil engineering schools. Like civil engineering, the major force that drives the need for surveying services is related to the demand for real estate, construction, and transportation. As cities grow in size and importance so does the value of the land and real estate contained within them and their surrounding urban, suburban, and adjacent lands. Smaller land parcels in larger quantities are required to support the housing needs of cities. This coincides with the development of transportation infrastructure within cities and to connect cities. Just about all modern development is undertaken after surveyors locate existing infrastructure and position the critical points for construction of the new facility. Surveyors report their work and findings on maps, plats, plans, sketches, and reports. The work of surveyors has infinite variation in scale and size. Surveyors undertake the finest of measurements in industrial machinery positioning (usually to a tenth of a millimeter) to the measurement from one continent to another (to centimeter accuracies) to better understand plate tectonics. While these examples are at the extremes of the types of measurements surveyors undertake, the majority of Professional surveyors measure to the centimeter level over distances of less than 2000 meters. Measurement and locating objects on or near the surface of the earth represents the majority of the scientific skills of the surveyor. Surveyors also have a detailed understanding of the legal aspects of land ownership. During their education, surveyors usually study more land law than most lawyers. This understanding of legal precedent regarding land law dictates the weight of evidence the surveyor uses in boundary retracement. In doing this work, surveyors are extremely cautious as to the accuracy and precision of their measurements. This caution is brought about by the value of the objects being measured and also the governmental standards required of surveyors before being given the license to survey land and real estate boundaries for the public. Errors in locating expensive structures and expensive real estate can result in extremely large monetary losses. To avoid these losses most advanced free market economies require minimum education and professional experience standards for the Surveying Profession. When to call a Surveyor The surveying profession rarely serves individual members of the public. The vast numbers of clients to the surveying profession are other professionals or administrators. The exception being those rare members of the public who possess vast land holdings. The majority of traditional clients to the surveying

3 profession are lawyers, engineers, architects, landscape architects, title insurance companies, real estate brokers, land development companies, and construction companies. Many professional surveyors work in the public sector at all levels of government. While the majority of professional surveyors are concerned with land measurements, a few may also specialize in geodetic surveying (the measurement of the shape of the earth), hydrographic surveying (the measurement of ocean, sea, and lake beds), industrial surveying (precise positioning of industrial machinery), or mining surveying (mapping and locating underground tunnels and mine shafts.) Professional surveyors are called upon to precisely locate natural or artificial fixed objects on or near the surface of the earth. These locations are then represented, usually for some form of legally binding purpose, as maps, plats, plans, sketches, or reports. Locations may be depicted as relative (pertaining to the relative locations of objects such as boundaries established from some existing point or boundary) or absolute (pertaining to an established mapping coordinate system such as the US State Plane Coordinate System.) In undertaking the positioning of any fixed object, the professional surveyor, in conjunction with the client and/or statutory regulations, knows the desired positional tolerance or accuracy required for the locations being determined. These accuracies vary depending on the nature of the survey being undertaken and the cost and risk involved. Usually a rule of thumb applies that the higher the accuracy, the more expensive the measurement equipment is required, the more time and effort involved, and the higher the cost of the survey. For example, consider the difference in measuring equipment and effort required for a professional surveyor to accurately locate the foundations of the World Trade Center Towers to a two-story residential house on a suburban lot. Like most other professions prudent professional surveyors carry professional liability insurance. This combined with the requirement for licensure in developed jurisdictions gives clients the reassurance that the results of the surveyors work is very reliable and legally defendable. The professional surveyor should be called upon to determine locations of points on or near the earth s surface if the risks involved in miss-location outweigh the cost of the services provided by the professional surveyor (Jeffress, 2003.) GIS Opportunities for Surveyors As Geographic Information Systems (GIS) infiltrates ever-increasing sectors of the economy there is a growing demand for greater spatial accuracy and accountability for spatial information. Much of the spatial information used as the mapping base for GIS will need to be derived from original measurements with scientific and statistical proof of the accuracies and error budgets. This is the domain of the professional land surveyor. The professional surveyor has skills in understanding the physics of measurement, the mathematics and statistics behind requiring multiple and redundant observations, and the legal liabilities associated with spatial

4 information. Those wanting to create more accurate GIS spatial data in order to minimize the risk associated with ever increasing value relying on GIS information are increasingly seeking these skills. Professional surveyors have the skills to assist GIS users reduce risk and to create value in GIS information. The following two examples show the added value that the skills of professional land surveyors can bring to GIS. While the examples discuss the spatial measurement technologies used by surveyors in obtaining the original on-theground measurements and their digital cartographic visualization, by far the greatest value added is the paper trail and management of error budgets that go into reducing the liability attached to the data and information depicted in the final product. Example 1: Local Government Base Mapping It has been suggested that 90 percent of all the processes involved with the running of local government involve spatial data and information. The majority of these processes relate to services provided to individual land parcels lying within the local government jurisdiction and the streets used to carry services and to access land parcels. To keep track of these land-parcel-related services, local governments have traditionally kept track of the location of each land parcel within its jurisdiction using parcel base maps depicting property boundaries. These parcel base maps are often referred to as cadastral base maps (Definition: cadastre: A public record, survey, or map of the value, extent, and ownership of land as a basis of taxation). It is no surprise that local governments were some of the first organizations to see the advantages of using GIS as an efficient tool to manage land-parcel and infrastructure information for their day-to-day operations and management. Throughout the 1980s and 1990s local governments represented the largest single group of GIS users. With their ever-increasing reliance on GIS, local governments are seeking more spatial accuracy for their land-parcel base maps. As the surveying profession initially constructed these land parcel boundaries, it is no wonder that local government is turning to the surveying profession to assist in land parcel base mapping. This example shows the surveying profession assisting in GIS cadastral base map construction for the City of Corpus Christi, Texas. Before digital mapping became efficient, cities were faced with the large cost of updating paper based parcel maps using aerial photography which captures data on the date of the flight then progressively goes out-of-date over time. In the mid-1980s the City of Corpus Christi looked to GIS to create an ever evolving, up-to-date digital map of the city based on existing survey plat data. The end result is a digital cadastral base map that uses over 750 precisely located GPS points to mathematically tie together original surveyed bearings and distances from survey plats (see Figure 1). It is important to note that the creation of a digital cadastral base map is a mapping exercise and not an exercise in boundary definition for land title purposes. The City of Corpus Christi set out to achieve a goal of having the parcel base map locations within 1.5 feet of their true position in Texas

5 State Plane Coordinates based on the North American Datum of While this goal was achieved over the majority of the City, there are still areas of the City that do not meet this goal due to the age of the surveys that created the land parcels. These areas can only be accurately depicted in the GIS cadastral base map once the true title boundaries have been established by re-survey and re-platting. Over time, as property values increase, these areas will be re-surveyed and will be transferred to the base map. The City has, as part of the subdivision and re-platting process, a procedure to capture updated surveys to be entered onto the cadastral base map. Figure 1. A Sample of the Corpus Christi Digital Cadastral Base Map showing GPS control points.

6 Figure 2. Detail of Corpus Christi Digital Cadastral Base Map showing lot boundaries and coordinates in NAD 83 State Plane.

7 Figure 3. Survey plat of the lots shown in Figure 2. The bearings and distances from the plat were used to precisely construct the Corpus Christi Digital Cadastral Base Map in NAD 83 State Plane Coordinates.

8 Example 2 Utility Mapping Utility companies manage large networks of infrastructure that cover large areas and service very large customer bases. Utilities can be above ground, below ground, or a combination of both. A major component of utility services is the supply of energy to customers and by the very nature of the products provided these facilities are hazardous to the public if damaged by human interference of by natural forces. Precisely knowing the location of hazardous utility infrastructure can greatly assist utility companies manage the risks involved in providing these services and to be able to quickly respond to natural, accidental, or terrorist damage to utility infrastructure. Because of the potential for loss of life or large monetary losses related to utility services, precise utility infrastructure positioning and mapping is becoming the norm in using GIS to manage utility networks. Utility services are located with easements (definition: A right, such as a right-ofway, afforded a person to make limited use of another's real property), which provide the real estate to carry the service to the customer. In many instances these easements co-inside with the street with services running underneath or above sidewalk space or the roadway. Utility easements can also run over private property. Easements affect rights to property; they have value to the utility company and can lower the value of real estate that is burdened by a utility easement. The value of an easement is dependent on the price of land and the size of the easement. Surveyors are required to precisely locate easements as they affect title to land and the right of the utility company to service the utility without trespass on privately held land. Not surprisingly, utility companies have many survey plans showing easements used to carry their services. Utility companies also employ surveyors to locate and manage these data about easements. Modern utility management now relies on GIS to store and manage utility infrastructure and easement data, which has been put in place by surveyors. Reliant Energy Inc. is an electric and gas utility company based in Houston, Texas that has built an extensive GIS to manage its real estate and utility infrastructure. The GIS division of Reliant Energy evolved from the Survey division. The precise location of property data and utility data is critical to tracking costs, company real estate assets, and reducing risks in the provision of electric and gas services to domestic and commercial customers. Figure 4 shows locations of electric utility features located by professional land surveyors on the Reliant Energy GIS.

9 Figure 4. A sample of Reliant Energy s GIS showing electric utility infrastructure and survey data. Why Most Surveyors will not Touch GIS The majority of professional surveyors remain focused on their responsibilities for the definition of cadastral boundaries and in keeping up with construction surveying. Recent trends have seen the number of professional surveyors declining while the productivity of the surveying profession has been increasing. The surveying profession has clearly been taking advantage in technological advances in software development, efficient spatial measurement technologies and digital mapping to increase productivity. A few progressive surveyors have seen how these technologies can serve GIS applications and have moved to address this growing market for spatial information. The market for spatial information based on high-precision original measurements appears to be growing faster than the surveying profession can manage. The trend in increasing demand for professional surveyors has already seen higher salaries and compensation for professional surveyors. This is not surprising as the value of the real estate and construction dependent on the surveyor s work is also sharply increasing. Increased compensation for the vital work professional surveyors undertake is directly related to the risk involved if the work is not performed correctly. Professional surveyors are educated and trained to minimize errors in spatial measurement so as to minimize the risk of the

10 user suffering loss as a result of inaccurate spatial information. A great deal of the work professional surveyors perform is related to the legal requirements (plats and legal descriptions of real property) associated with the real estate market. Real estate is the largest category of tangible assets within the economy. It is no wonder that surveyors command high fees when so much value is riding on their work products, especially when the demand for survey data and information continues to grow along with the population and the demand for real estate. While demand for surveying services continues to grow we are seeing a decline in the supply and number of professional surveyors. For example, this shortage is reflected in the number of surveyors (RPLS) actively practicing in Texas. Figure 5 shows the number of Texas profession surveyors registered with the Texas Board of Professional Land Surveyors by age group. The total number, 2573 as at July 2004, is down from 3500 a decade ago. What is of most concern is the fact that 19% of the active surveyors are over the age of 65 (approximate retirement age) and that there are more active surveyors over the age of 70 than there are under the age of 40. The median age is 54 years, which suggests that half of practicing surveyors are approaching the end of their careers and are unlikely to take up the challenges of serving a new market involving learning new technologies while the market for cadastral services continues to expand. Number of RPLS as of 12/31/ >70 Age Groups Figure 5. Active Professional Surveyors in Texas by Age Groups. Total = 2,573. RPLS s 65 years or older = 473

11 The simple economic theory of supply and demand has seen the value of professional surveying rise. Salaries and fees for professional surveyors are rising. Many surveyors who wish to retire find that there are few younger surveyors willing to buy or take over their practices and are forced to remain active in order to maintain the value of their businesses. Graduates from professional surveying degree programs have multiple job offers with guaranteed long-term employment. The surveying schools are actively trying to increase enrollment with the assistance of professional surveying societies. These efforts see limited results as the greatest obstacle is overcoming the very low profile the surveying profession has with the public. Increasing salaries certainly help attract students. Meeting the Demand for Accurate Spatial Data The data on the declining number of professional surveyors represents an opportunity for GIS professionals. Professional surveying is a specialized sector of the wider GIS and spatial information industry. Many GIS professionals have a unique background that can be the foundation of a professional surveying career and hence an entry into the expanding need for accurate GIS spatial data. Turning again to the state of Texas as an example, the requirements for becoming a licensed professional land surveyor are the following: 1) A four-year degree with at least 32 credit hours of surveying related courses. These courses are defined of the Texas Board of Professional Land Surveying web site (see which describes the number of credit hours allowable for each topic area. Many of these topic areas are included in four-year GIS degrees. 2) Sit for and pass the national Surveyor in Training exam complied by the National Council of Examiners for Engineering and Surveying. This is a college-based examination that covers the fundamentals of surveying measurement and supporting sciences. 3) Obtain two years of work experience under the responsible charge of a Registered Professional Land Surveyor in cadastral surveying. 4) Sit for and pass the Texas Board of Professional Land Surveying professional examination on Texas Land Surveying. (Texas Professional Land Surveying Practices Act, amended 2001) While these tasks may appear daunting to a graduate with a degree specializing in GIS, it will become abundantly clear that the basics of spatial data measurement will have been covered in any reputable GIS degree and that there is a vast overlap in the spatial measurement technologies used in GIS and professional surveying. There are many rewards in approaching the need for GIS spatial data with the qualifications of a professional surveyor.

12 Conclusion Surveying professional can bring much in the way of added value and decreased risk and liability to the creation of GIS spatial data. There is strong evidence that the number of professional surveyors is declining to a point where there are not enough to meet the demand for cadastral surveying services without the extra demand for original measurements to create accurate GIS spatial data products. This presents an opportunity for GIS professionals to expand their skill sets to take on the role of the professional surveyor and to satisfy an ever-increasing demand for accurate spatial data. There will always be a need for the services provided by professional surveyors as the real estate market continues to grow and develop. Along with the demand for new GIS spatial data products the current professional surveying work force needs the reinforcements that the GIS industry can supply to meet these demands. Both the surveying profession and GIS profession can benefit from cross training and education to better serve the entire spatial data needs of the future. Acknowledgements I would like to thank Mr. Larry Messer, GIS Coordinator for the City of Corpus Christi for his valuable advice and for providing the images of the city s land parcel base maps. Mr. Jeffery Myerson, RPLS, gave me valuable assistance in sharing his experiences and images from the Reliant Energy Inc. GIS. Financial assistance for the production of this paper was also provided by the National Science Foundation through Grant # DUE "Geographical Information Systems Technology Implementation Project (GIS-TECH)," is under the direction of Phillip Davis, Barbara DuFrain, Gary A. Jeffress, James A. Wall. References Bedini, S.A. George Washington ( ) Surveyor and Cartographer, Part 1, Professional Surveyor, September 2000 Davis, Henry, Index to Ancient Maps, Jeffress, G.A., The Value of the Cadastral Surveying System to Efficient Land Administration Systems, Surveying and Land Information Systems, Journal of the American Congress on Surveying and Mapping, Vol. 63. No. 4, pp , Texas Professional Land Surveying Practices Act, amended 2001,