My Semester in Elementary Surveying
I've been a volunteer for the North Alabama Rail Museum in Chase, Ala., for 14 years. Much of my time has been devoted to researching land, title and deed records for historical and legal purposes. I interact with many civil engineers and surveyors. In my work life, I am a cartographic product finisher for the mapping/geospatial division of a prominent software service provider. Put this experience together and it should be no surprise that I decided last year to continue my education in civil engineering, GIS and surveying. I have always believed that in order to succeed in any field, one should never stop learning. So, I looked to my local university for more learning opportunities. I thoroughly enjoy being a surveying student and know that surveying is definitely my long-term career goal. Here is a snapshot of my first surveying semester.
The SyllabusThe Department of Civil and Environmental Engineering at The University of Alabama in Huntsville (UAH) has four divisions: environmental & water resources engineering, geotechnical engineering, structural engineering & structural mechanics, and transportation engineering. Students who pursue a degree in any of the four divisions are required to complete the Elementary Surveying course. Students of the department of transportation engineering division are also required to complete the Advanced Surveying course.
The Elementary Surveying class teaches students about the basic theory and practical field methods of surveying used in many engineering applications. Some of the topics covered during the two semester-hour course include measurements, leveling, traversing, stadia, topographic surveys, mapping, circular curves and errors in surveying. Each week students attend a one-hour classroom lecture followed by a two-hour lab session where field exercises are conducted. This 2:1 ratio of field study and class study gives students the benefit of real, hands-on experience.
Before any lab exercises are conducted in the field, one of the first classroom discussions of the course focuses on the importance of surveying field notes. Despite having the convenience of modern automatic data collectors, the course instructor, J. Shelby Aston, PLS, emphasizes to the students the continued importance of taking accurate field notes. Aston is the senior land surveyor for the engineering department of Madison County, Ala. In addition to the field measurements being recorded, some other data to track in a field book may include the job number, date, the time of day the survey was conducted, the names of crewmembers involved, instrument type/brand/serial number, and the current weather conditions. Field notes also include sketches or layouts of the job.
The textbook that is used for this course is Elementary Surveying: An Introduction to Geomatics by Dr. Paul R. Wolf and Dr. Charles D. Ghilani. Aston assigned problems from the end of each chapter covered during the semester. The related field exercises were then typically scheduled after a given chapter from the book was covered in class. During the first day of field study, Aston gave students a walking tour of the 1.52-acre parcel of land (owned by the university) that was used extensively throughout the course. The tract of land consists of six pre-established points (A, B, C, D, E and F) as shown in Figure 1.
The Field WorkThe outdoor experience has been described by students as "relaxing" and "adventurous." One of the first field exercises that provided students with some hands-on experience using surveying instruments was the turning of angles. Following a demonstration, students spent much of the first day in the field practicing the setup and leveling of an early 1960s K&E transit. This unit required the use of a plumb bob during setup and proved to be quite a challenge for many students. Later, field exercises included similar setup procedures and the proper use of a theodolite. While turning the angles in the field, both the digital readout and the optical plummet found with the theodolite were a welcome sight to many students. This was the first good indicator to the engineering students of just how much the technology has advanced throughout the history of surveying.
Once all of the interior angles were turned and the loop closed, the next topic of study in the field was measuring with a 100-foot steel tape. Aston invited his colleague, Bob Dozier, PLS, to assist him with this particular field demonstration. Together as an experienced team, he and Aston measured the first distance from point A to point B using the tape and plumb bobs. Their measurement was recorded in the field book as 322.65 feet. Next, the students took turns taping, and as expected, many of the student teams came up with varying measurements. During this demonstration, Aston discussed the correct methods for taping including the throwing of the chain, lining in, applying tension, plumbing, reading tape lengths and recording distances.
Throughout the semester, most of the field study was conducted following a preliminary classroom discussion. Students, perhaps especially surveying students, may sometimes develop a better understanding of the material covered from a textbook if they first get to witness an actual field demonstration. One example of this approach involved measuring with the steel tape. Once the students were shown how to measure accurately with a tape through a demonstration, the material found within the textbook made a lot more sense. In retrospect, the study of surveying can be conducted successfully in either a class-to-field or a field-to-class format.
Bring on the Modern EquipmentAs the midterm of the semester was drawing near, the students needed to prepare for the class project of producing a hard copy plat of the field survey. In order to complete this assignment accurately and in due time, more measurements from the field were needed. This prompted Aston to bring out more modern surveying equipment. The university owns two Sokkia (Olathe, Kan.) Set 10 total stations, which are used in the surveying classes. In the field, students were shown how to properly set up, use and handle the units. Aston asked a student to volunteer as the rodperson and carry a single prism out to station B in the tract being surveyed. Using the electronic distance measurement (EDM) function of the total station, a measured distance from point A to point B was recorded in the field book as 322.64 feet, a mere 0.01 feet different than what Aston and his colleague had measured earlier using the steel tape.
Students then split up into teams measuring distances and re-checking the interior angles at each point using the total stations. During the next classroom meeting, Aston sketched a sample plat on a whiteboard and asked the students to provide him with the measurements they had recorded in their teams' field books. When one student provided a given field measurement, a number of students from the other teams intervened, stating that their measurements were different. One student gave her team's measurement from point D to point E as 214.44 feet while another student insisted that his team measured the same boundary line as 214.47 feet. Here, Aston brought the student's attention back to order with one of the most fundamental considerations to teach about surveying: while surveying in the field, there is no such thing as a true measurement. Many variables can be factors in measuring.
As explained in Chapter 3 of Elementary Surveying: An Introduction to Geomatics, environmental variables such as wind, temperature, humidity, trees and atmospheric pressure can all impact the accuracy of field measurements when using the various types of surveying equipment. Human errors can often be involved as well, and these errors are not necessarily a random thing. They can simply be due to the limitations of human senses. In any event, Aston relays to students how both natural and random errors must be taken into account when surveying.
Going Back to the BasicsDuring the first half of the semester, many students with prior experience in surveying asked, "Why not use the more modern equipment like a total station at the start of the semester and be done with the surveying project that much faster and easier?" Aston explained that the purpose of utilizing some of the more basic surveying tools at the start of the course was to give students a better foundation for the understanding and appreciation of surveying. The initial use of the more basic tools and instruments, he says, will "enhance a student's ability to compensate for the errors that are typically found in your modern day-to-day surveying operations." Many deeds and legal descriptions, for example, may include working units that are given in chains, rods or some other form of measurement. To be successful in the study of elementary surveying, a student surveyor or engineer must be able to account for any variances that stem from the use of these older technologies.
As the student teams became better acquainted with the Sokkia total stations in the field, Aston's classroom discussions focused on how to account for the other types of errors found in surveying such as angle misclosures. Using the preliminary distances and interior angles that the student teams measured in the field, a total angle misclosure of approximately 2'15" was found. This is based on the formula:
Total Closure Angle (TCA) = N - 2 (180 deg)
where N is the total number of turns (angles
Substituting the number of turns as "6" into this equation, the TCA should come out to be 720 degrees. The sum of the angles from this initial survey, however, came out to be 719°57'45". For the traverse loop to close geometrically, the total angle misclosure of 2'15" had to be divided among the six interior right-hand angles.
Before proceeding further into making the needed corrections, Aston discussed the various forms for the measurement of angles. Among those discussed were the use of bearings and azimuths and a variety of mathematical models used for converting data among the different systems. The preliminary interior angles taken from the class field project were used as a practice exercise for these conversions. The correction of these preliminary angles, however, was only the first step in a series of traverse computations. With the angles now corrected and converted into bearings, the next step to learning about elementary surveying involved the use of latitudes and departures. This is one of many different approaches that can be used for traverse computations. In these exercises, the preliminary bearings and distances were all mathematically corrected and the students were expected to comprehend the necessary procedures involved. Aston also introduced the use of a coordinate system. The result was a new set of adjusted bearings and distances that work out to have the correct geometric closure. Each point was then assigned a coordinate value as well. Today's modern field-to-finish software can perform these computations quickly and accurately using raw data collected from the field; however, the importance of understanding the methods in which these calculations are being performed cannot be denied.
The Most Important LessonsIn the beginning of the semester, Aston mentioned that the class of Elementary Surveying is not intended to prepare students with everything they will need to become professional land surveyors. This class, however, does provide each student with an understanding and appreciation of surveying, which is essential in all facets of civil and environmental engineering. Students who take the Advanced Surveying course are able to enhance their knowledge and understanding of surveying even further. This second course in surveying at UAH includes a recap of public land surveys in addition to other topics that include GPS, boundary surveys, construction surveys, as-built surveys, and the layout of horizontal and vertical curves.
The surveying classes taught at UAH provide a student with an excellent overview of what all the different facets of civil and environmental engineering will involve. The methods of instruction, the lab demonstrations and the fine selection of surveying equipment used for surveying at UAH all set a good example. As outlined in the class syllabus, Aston's goal was for students to have fun during the course while learning about surveying, past, present and future. As a subtle bonus, the course also enhances a student's appreciation for quality teamwork, effective communication, patience and the freedom to enjoy learning-attributes that will help a person succeed in land surveying or any engineering discipline.