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As technology has become more accessible and mobile there is a misconception that it has the capability of producing better results and is on course to replace traditional methods. This is a discussion I have had with other adjuncts and professionals who have taught courses at City Tech. The methods we teach are applicable to first- and second-year civil engineering and construction management technology students in New York City and are currently based on traditional surveying methods. The course is an introduction to land surveying equipment and techniques and so most students are unfamiliar with the terms used to describe a plane two dimensional versus a geodetic or three-dimensional surface. At this point in their academic career they have only been exposed to plane geometry and trigonometry, so we start by describing a location as a point on a local two-dimensional grid. Then we say we want to use this point as a reference to mark the positions of other points on the grid, which is a nice segue into error and accuracy. Because the students have not taken a course in statistics, we focus on the importance of repeating measurements to catch mistakes in the field rather than data quality and accuracy standards.
At this point in the course we introduce the vertical component and define the location of a point on the grid in an x-y-z coordinate system. Then we talk about what is a datum and the methods used to establish horizontal and vertical control. The differences between spherical and plane coordinates becomes apparent when I use Google maps and Google earth to emphasize why scaling factors are needed to correct projections of distance measurements on a map. Defining angles referenced from north on the compass and taking angle measurements is more challenging for students as it requires them to visualize a point in three dimensions and use trigonometric relations. When to introduce GPS and GNSS into the course material has depended more on the student’s interest than course pedagogy. The students must understand how points can be referenced in two dimensions before jumping into three dimensions. The use of modern technology in land surveying applications is presented to students as an additional method of acquiring spatial data rather than the best method. The practice of surveying in a city like New York where you are surrounded by buildings as high as 1,500ft would be an arduous endeavor using geodetic techniques if it were not for virtual networks of reference points that the state and private companies have established throughout the city.