Sect_5.2.1

5.2.1 GPS Survey Planning

INTRODUCTION

Project planning is one of the most important aspects of GPS surveying, as careful planning maximises the chances of the survey achieving the desired accuracy, within a reasonable time and to budget.

Before commencing the planning of a GPS survey it must first be established (a partial list only!):

What is the purpose of the survey?
What are the accuracy and reliability requirements?
What resources are available?
What previous surveys have been carried out?
Are there any special (or unusual) characteristics of the project?
Is the surveyor suitably equipped (in the broadest sense of the word) to carry out the GPS survey for the client?

Elements of the GPS Survey Planning Process

Unlike conventional surveying technologies there has generally not been sufficient time for the average surveyor to have amassed the "conventional wisdom" needed to reliably execute GPS surveys. Careful planning is therefore still a critical issue and consists of the following elements:

PROJECT DESIGN: involves project layout and network design, and is driven primarily by accuracy and station location / density requirements (defined by the client), productivity / economic considerations (of concern to the GPS surveyor), and standards and specifications (promoted by the geodetic control authority).
OBSERVATION SCHEDULE: giving consideration to such factors as the number of GPS receivers, occupation time per site, number of sites per day, requirement for multiple station occupancy, etc.
INSTRUMENTATION & PERSONNEL: instrumentation appropriate for the task, mainly driven by what may be available inhouse or what could be hired from outside the organisation. Also, adequately trained personnel are needed in order to carry out the survey and process the data.
LOGISTICAL CONSIDERATIONS: issues such as transportation (appropriate to ensure observation schedule can be adhered to), special site requirements (for example, power, intervisibility, etc.), and factors related to network design and observation scheduling such as the receiver deployment pattern, etc.
RECONNAISSANCE: which may or may not be necessary, depending upon how "critical" the GPS stations are to be to the overall project, whether permanent marks will be established, etc.

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