This week Invar Mapping commenced the latest phase of our ongoing survey at the West Midland Safari & Leisure Park. This phase is to undertake the topographical survey of the reserve. The reserve is about 100 acres. So far this last week we have surveyed the carnivore sections (Wolves, White Tigers, African Lions, Cheetahs and the Wild African Dogs) between 7am and 10am for safety reasons. We have then tackled some of the other less risky areas after 10am each day. On Wednesday and Thursday we had to be watchful because of the close proximity of the Rhinos. Thanks must go to the escort staff for keeping an eye on us whilst we did the survey. I only had to run & hide from the Rhinos twice on Wednesday and sit in the Jeep for a short while on Thursday. With their assistance we have been able to concentrate on our survey work and make better progress than I had anticipated. We still have some tricky areas to do. Hopefully we can carry this good progress forward to the remaining areas.
When we started surveying the park in 2001 we used conventional survey techniques. Whereby, a total station (in our case a Nikon total station) is used by a surveyor and an assistant. One driving the total station (recording and coding the data and physically aiming the instrument), the other placing the detail pole (to which angle and distance measurements are taken) on points on detail on the ground (building corners or manholes for example). As the data is collected a glorified ‘dot to dot’ is built up and a map of the site generated.
Last year we introduced our Trimble 5600 series ‘one man’ robotic total station to the park. In ‘one man’ mode the surveyor is able to control the total station from the detail pole. The total station uses a radio link to transmit the measurement data to the detail pole. The instrument has servos motors built in which allow it to track the detail pole automatically. This kit proved a huge boon on site last year. The picture is of me by the park entrance with our robotic total station.
This year, largely because of the number of enclosures on the reserve, we have also taken our Trimble R8 ‘VRS Now’ GPS system to the park. This has allowed us to survey each cell, without the normal convention of linking control stations by traversing through them all with a total station. With restricted vissability between each of the cells a convetional approach would be neither practicle or cost effective.
Having taken the VRS route we have been able to considerably improve our productivity on site. With a conventional survey you have a survey team (made up of a surveyor and an assistant) who work with one set to kit to produce one set of data. By using the robotic total station in ‘one man’ mode and in conjunction with the VRS GPS, we have been able to split up the team in to two ‘one man’ teams. There are locations where this is not possible. Poor satellite coverage or the close proximity of the reserve animals placing the total station at unacceptable risk are two of the main reasons. In these cases we can revert to type and use the total station as a traditional survey team would.