A Guide to First Principles
J.A.L. Cavill FIS Aust, MIEMSA
This book is intended for students undertaking Survey Engineering for the first time. The author, an Australian surveyor, is very well known and respected from his days as a field surveyor on the Snowy Scheme, engineering and real property surveys in Canberra for the Australian Government, and through to his teaching at Curtin University and the University of WA. These latter appointments saw him emerge as the classic "father figure" to the majority of his students.
The style of the book, reflects closely the teaching style of its author, affording its students, a thoroughly readable, logical and uniquely presented textbook. The worked examples are clear, easy to follow and there are enough examples for the most inquiring mind.
Chapter 1 – Fundamental Survey Calculations
Most surveyors will agree with the material and examples provided in this section. The author’s discussion of the principles of "significant digits" will be welcomed by those who have experienced the vagaries of results, quoted by engineers and architects to 3 decimal places, that were measured with a precision of +1 m.
Chapter 2 – The Plane Table
Many practitioners will do a "double take" at the notion of the Plane Table’s being included in a modern surveying text, but as the author points out, "although Photogrammetry, Total Stations and Computer Aided Drafting have superseded Plane Tabling in the production of maps, it still remains a most useful medium for the teaching of surveying principles". In the days where a number of surveying courses leap into modern field techniques, before the principles are properly understood, the author’s argument has some merit.
The treatment of the plane table techniques, reflect both the author’s great love of the Plane Table and also his years of practical teaching experience.
Chapter 3 – Levelling
There is a very detailed treatment on the subject of levelling. The introductory sections of this chapter are outstanding from a teaching point of view. The treatment of the theory of levelling, the various kinds of instruments, the staves, the testing and calibration of equipment, is very thorough. The coverage of field techniques, booking procedures, checks and reductions, is more than adequate for any survey student. Being a text aimed at Survey Engineers, it is surprising to find that the technique of Laser Levelling is not covered, except for a brief mention in the introduction.
Chapter 4 – Vertical Curves
It was surprising to find that the material in this chapter, was presented without any preamble as to the application of the subject matter, in stark contrast to the other chapters of the book. A paragraph of introduction as to why the survey engineers should be dealing with Vertical Curves, would have enhanced this chapter as a teaching tool.
Never-the-less the material in this chapter is presented in a detailed, logical manner. Of particular merit is the section dealing with the comfort factors of vertical curves and the length of a vertical curve. The worked example fitting a vertical curve to a given profile is outstanding in its clarity and detail.
Chapter 5 – Areas and Volumes
The treatment of this subject, starts with the author’s familiar patter, of a thorough treatment of the historical ways of dealing with areas, from the most approximate up to the most accurate, covering such implements at the planimeter and electronic planimeter. When dealing with areas by Coordinates, the author has omitted the general equation:
S(Xi+1 – Xi)(Y i+1 + Yi)/2
which is required if the calculation is to be computerised.
The section on volumes, is very well treated but the more modern computer techniques of calculating volumes by triangle networks is ignored.
Chapter 6 – Angle Measurement
The general treatment of all classes of Theodolite and Total Station, is quite outstanding. The author has managed to distil all the really important factors affecting the performance of a theodolite, into a very readable, easy-to-follow dissertation. The detailed section of the chapter dealing with the axes of the theodolite, setting up and testing the adjustment, logically proceed from this early introduction. The author’s long experience in the field, under all condition, is evidenced in his practical treatment of centring, a subject sometimes ignored by texts. The method of reading angles by directions is well treated, but the repetition method is not treated.
Chapter 7 – Distance Measurement
The introduction to this chapter is another example of the author’s ability to place his material in the broader context. His comparison between the steel band and the EDM is a clever analogy, which will undoubtedly give the student a solid base on which to place two dissimilar instruments. The treatment of steel band measurement, is detailed and thorough and while there is not as much detail on EDM measurement, the author constantly refers to his earlier analogy to bring home the similarities between the instruments, wherever it is appropriate.
Chapter 8 – Theodolite Application
Here the author builds upon the earlier material, covered in the chapters on Plane Table, which use the first principles of angle measurement. The author treats a number of topics including eccentric stations and radiations, the latter of which he points out have gained in popularity since the introduction of built-in EDM devices. His warning about checking radiations is as timely as it is cogent. The treatment of various kinds of traversing is again very complete, with the author cleverly blending EDM and traditional techniques. He makes reference to the need for students in particular to go on booking field measurements, even when measuring with an EDM. Traverse closures and adjustment, are explained in great detail with excellent worked examples.
The treatment of the Resection which has also gained popularity since the introduction of EDM and Computers, is also well treated, although the classic resection by angles, is the only material covered in the text. The suggestion reduction sheet for the worked example is a delight in its clarity.
The text also has a well explained section on vertical angle measurement, with a concise treatment of Trigonometric Levelling.
Chapter 9 – Horizontal Curves
This topic is particularly well treated, from both the theoretical and practical points of view. The notation which is used throughout the text conforms with the "Cogo" notation, making it possible to easily computerise the formulae. The notation would have been enhanced had it included the sign conventions of "positive to the right and negative to the left" which are necessary to convert the notation into general purpose formulae.
The section dealing with pegging curves from various stations on the curve or the centre, is very thorough, supported by quite detailed examples and calculations. It was fascinating to the reviewer to read the section dealing with pegging a curve, as the authors very logical explanation, was exactly the same as he gave in the field, in Canberra to a struggling survey cadet in 1961.
Those who have had to solve practical inaccessibility problems in the field, will welcome the treatment in this chapter. The examples are always sufficient and detailed in their explanation. Similarly the treatment of the Spiral or Clothoid curve, deserves special mention for the succinct explanation of the formulae. Working with numerical examples, rather than plain theory, is a great teaching tool.
All of the setting out procedures are geared to setting out using a calculator, thus obeying the author’s "first principles" stance, but the text would have been rounded out with a little more emphasis on the part modern computer packages have to play on setting out procedures.
The example field sheets, which are included in the back of the book, for students to copy, are really useful tools, for most students have great difficulty in setting out their work in any coherent form. Most teachers would agree, that students need all the help they can get.
In summary, this text will suit anyone who is engaged in the teaching of engineering surveying, as it deals with the topics so very thoroughly, it leaves nothing to be further explained, save for updating the material with more modern techniques as mentioned above.
Geoff Bebb FIS Aust F AusIMM