Real time kinematic GPS survey equipment provides cost and time savings

Leica 1200 Systems Unit

Since 2005 our Saskatoon office has been using real time kinematic (RTK) GPS survey equipment. Our GPS experts, Johnathan Nagyl and Jason Forest, advise that, “After we started using the equipment last year, we quickly discovered the time efficiencies and competitive advantage that the equipment offers. The equipment is also versatile. We have used it to obtain data in a number of ways.”

For example, by mounting the RTK GPS on a passenger truck, surveyors can obtain existing centerline information at highway speeds. Mounting the unit to an all-terrain vehicle (ATV), surveyors can obtain original ground survey using either a time or distance interval setting for automatic data pick-up.

Associated Engineering uses the Leica 1200 base station and rover. A Garmin modified sonar attachment was recently purchased, which enables the unit to be mounted on a boat and used to obtain bathymetric data for lake and river bottom contours. This is an application for surveying rivers and lakes when designing new raw water intakes, bridges, dykes, and dams. The RTK GPS allows the designer to make an informed decision on the most suitable location for the infrastructure based on the survey information.

Garmin GPS Modified Sonar

The base station can send high accuracy transmissions up to 12 kilometres in typical conditions, and up to 15 kilometres in optimal conditions. Using traditional total station equipment, the user must disassemble and reassemble survey equipment when the total station is more than 250 metres from the survey location. On large or linear construction projects, disassembly and reassembly can be very time consuming. Using the RTK GPS, the base station is usually setup once per day and the user transports the rover wherever the survey is required. Another advantage is that the RTK GPS does not require line of sight from the set-up location, unlike total station equipment. The GPS requires line of sight from the satellites in orbit above the earth. Thus, the RTK GPS equipment saves time in busy urban areas where traffic and other obstructions interfere with the line of sight.

Base Station

Construction survey layout has proven to be very simple and cost effective using the RTK GPS. The system comes equipped with many useful survey functions for construction layout. A stakeout file can be created and saved as a simple comma separated value (csv) file containing point number, northing, easting, elevation, and descriptor. Various stakeout methods and orientation choices are provided in stakeout mode. The user can navigate directly from a map or with text and graphical aids.

Associated Engineering has used the layout capability of the equipment for stakeout of the horizontal location for pipelines and urban roadway layout, including concrete medians and islands, curb and gutter, traffic signals, and lane markings. Our experience shows that layout is approximately four times quicker than conventional methods while using half the labour.

The technology of RTK GPS surveying has allowed Associated Engineering to provide high quality, accurate, and repeatable surveys at a fraction of the cost of traditional survey methods. The project schedule and labour time savings gained through the efficiencies are making Associated Engineering more flexible and competitive, which benefits our clients.