Obtaining Critical Survey Information for Small and Large Scale Developments
Topographical surveys are made using a variety of tools and technologies for a whole range of purposes, from domestic alterations to industrial constructions.
Topography is a highly specialised discipline that involves the study of terrain and land formation and the representation of these features in detailed maps and charts.
Typical consumers of topographical surveys in Bristol
and the surrounding areas range from residents who are contemplating home extensions to multinational companies planning a major industrial project or civil engineers drawing up proposals for a new road or city bypass.
One of the founding forms of topography as we know it today is the famous Ordnance Survey, a phrase that is familiar to everyone and gives its name to the UK's government-owned mapping agency. Its origins lie in the mid-18th
century, when King George II of Great Britain demanded a survey of the Scottish Highlands. His objective was to create a map of the area to help his forces to locate and subjugate the Highland clans in the wake of the Jacobite uprising.
This naturally led to further surveying and mapping activities across the country and to the creation of the Ordnance Survey itself.
During this period, the great theodolites (pdf)
were designed and constructed. These were at the cutting edge of 18th
century technology, and include the Board of Ordnance theodolite that can be seen today at the Science Museum in London.
Just like their forefathers, today's topographers use the latest technological innovations to provide more detailed maps than ever before. These can be created in 2D or 3D, and in electronic or paper formats, depending on the customer's needs.
Surveyors use GPS tracking, robotic total stations and laser technology to ensure that the maps they produce are as accurate as possible.
Robotic total stations
In the early 1980’s traditional theodolites began to be replaced by instruments called “total stations.” These are the devices you might see from time to time on tripods by the side of the road. Total stations are integrated with electronic distance meters that allowed them to calculate distances with great accuracy.
With the new millennium came further innovation in the form of the “robotic total station,” also called a Geodimeter.
The robotic total station brought automatic tracking and radio communication, meaning that a surveyor was only needed at one end of the measured points, with no need for an assistant at the site of the instrument. Thus, surveys could be conducted quicker and with smaller crews, but with better levels of accuracy.
In some environments, it might be impractical or dangerous for the surveyor to physically access an area to collect data. Under these circumstances, today's topographers can use reflectorless technology.
This uses a laser to measure distances up to hundreds of metres without having to access the target. Two methods have been developed, known as “phase shift” and “pulse.”
There are advantages and disadvantages to each of these, depending on the environment and the distances being measured. However, the latest reflectorless techniques use a combination of the two, thereby getting the best of both worlds.
The world of topography has come a long way over the past 250 years – from the great theodolites weighing 200 lb to GPS technology and hand-held laser devices. Yet what has remained unchanged is that topography has attracted the attention and imagination of the greatest innovators. We can only imagine what the next 200 years mig