Using the latest technology such as a geographic information system (GIS) to find the spatial accuracy of some of our oldest travel routes in America is challenging, but it can be done. A few years ago, the North Carolina Railroad needed to compare its 160-mile corridor – established in the 1850s – with current-day properties. The 1851 hand-drawn maps were scanned and digitally placed over the present-day county aerial photos. The result was a graphical and data-rich representation of exactly where the original tracks had been laid, their migration to present day, and the adjacent properties abutting the railroad tracks and properties.
Every day, new and difficult spatial situations will be tested by using GIS technology to see if the answer can be found in the final map.
GIS also provided a superior means to visually assess features such as utilities, as well as the impact of any proposed action along the railroad corridor. Today, if someone needs to establish an agreement with the railroad for an occupancy along the corridor, the railroad must consider the existing and possible future actions in the vicinity of the proposed project – sometimes for miles in either direction of the current project. GIS has become the perfect tool for conducting both this visual process and the underlying analysis.
Using GIS to solve new or old challenges is only a beginning. Every day, new and difficult spatial situations will be tested by using GIS technology to see if the answer can be found in the final map. Locating old historical roads and checking the exact placement of railroad tracks and properties are only a couple examples of how GIS assists us all in finding a path to success.
Janet Jackson, GISP, is the N.C./S.C. Enterprise Solution Sales representative for Duncan-Parnell. She enjoys writing about how GIS is used to successfully intersect professionals and projects. She can be reached at firstname.lastname@example.org.
Maps are common output from a GIS, but the most profound products are actually found in the data analysis it performs beneath these pictures. Forecasting future conditions or behavior is one of those analytical capabilities that can be manipulated, in this case, to reveal our forgotten past.
My idea began simply enough: Use historic data to locate the path of colonial roads that formed the basis of trade in the backcountry of the Carolinas on the eve of the American War for Independence. My initial attempts focused on using GIS to warp and register map documents from the eighteenth century. This task was far trickier and much less fruitful than I had hoped, so I turned to predictive analysis. Simple calculations minimizing slope to predict paths between known points of interest was also underwhelming. It was only the introduction of soils data – which contained multiple descriptive measures of the suitability of each soil type to support traffic – that eventually led to a successful model.
The next hurdle was to validate the results. First, an extant road marker was discovered that identified a point 15 miles from the center of Charlotte ("XV To C") which matched the distance along my predicted route. The second confirmation came after driving down an insignificant-appearing road along a predicted corridor leading to Camden that contained a short segment named "Old Camden Road." It is these discoveries that highlight the most exciting analysis GIS is capable of calculating in the prediction of forgotten "old" data.
Forecasting future conditions or behavior is one of those analytical capabilities that can be manipulated, in this case, to reveal our forgotten past.
Dale Loberger is a GIS professional, and consults on GIS applications in public safety during the week, and enjoys demonstrating the use of historic surveying equipment after hours. He is involved in a research community known as the Historic Mapping Congress and can be contacted through Twitter: @DaleLoberger.