Topographic surveys are often also referred to as land surveys. They are simply drawings that map the topography of a site showing existing features and detail such as buildings roads, paths, trees and alike. Often, they show the level of the ground by way of spot levels or heights and contours.

Land surveys do not investigate the condition of the ground, that falls within the remit of a geotechnical survey or ground investigation.

Land or topographic surveys are the essential first plan that is required to enable the detailed design of a building, landscaping or civil engineering project. Without a topographic survey an architect or engineer is unable to see how his design will fit within the site and what existing features will be impacted by the proposed works. The survey helps designers mitigate the impact on the site and to plan and cost the proposed works.

*Laser scanning one of the shafts of the historic South Crofty tin mine*

The control stations established by the land surveyor enable the contractors setting out engineers to accurately set out the new project in the correct position with the floors and roads etc at the correct height.

The land survey forms part of the package of drawings that are required for a planning application so are a key early investment by a developer of any size.

Kemp Chartered Land and Engineering g Surveyors are regulated by RICS and have been trading in the south west since 1988 and so have almost 40 years experience in delivering topographic surveys from small domestic extensions to major highways covering tens of kilometres. We have a broad range of the latest equipment and in house expertise. We are always happy to discuss your project to ensure the optimum solution is found.

Types of Topographic Survey

Essentially a topographic survey is just that, what can vary is the level of detail collected, the way that it is collected and the accuracy.

What would be considered to be a standard topographic survey? The starting point for most drawings is the RICS 1:200 survey level of detail. Traditionally survey accuracy is defined by scale. At 1:200 something as small as a manhole cover will be drawn at the correct size and orientation because when plotted on a piece of paper you can still see this. At 1:500 scale the feature is too small when drawn so it becomes a symbol. At 1:1250 scale it would be just a dot and so would not appear at all.

Modern surveys are produced in CAD allowing designers to zoom in and out and so the default for most firms including Kemp is to work at 1:200 scale. This scale also defines the accuracy that you can expect which from points of hard detail should be within +/-50mm.

Surveys at 1:200 scale will be suitable for almost all domestic extensions and major civil engineering projects. The level of detail is high, most natural and man-made features on or directly above (not buried or hidden) the site are observed. Overhead service lines, ridge and eave levels, service covers, road edges and kerbs are all included. Dense vegetation can compromise survey observations. If you have any queries on the level of detail to be collected our friendly team are always happy to have a chat with you.

Techniques to Collect Survey Data

Total Station

A total station is the surveyor’s primary instrument. This is a computerised theodolite that is often controlled remotely by one surveyor and often referred to as a robotic instrument. It is generally the most accurate instrument that is used and is often employed for precise deformation monitoring when mm accuracy is required.

GPS/GNSS

is best employed to collect soft detail such as height/level data on unmade ground such as fields, quarries and earthworks sites. It can be mounted on quads or vehicles to assist with rapid data collection on large soft detail sites such as solar or wind farms.

Drone

UAV or UAS, more commonly known as drones are used increasingly by land surveyors who will need to have undergone training and licensing from the CAA to employ them. Kemp have several licensed pilots and drones.

Drones are best employed to cover large areas and areas where access may be difficult. The imaging collected can often provide developers with an added insight into the condition of a site and the orthorectified and the geo-referenced image that sits below field observations in CAD or PDF can often be invaluable.

Boundary & Hand Over/As Built surveys often benefit from UAV surveys. Initial feasibility surveys are another example when the developer does not want to cause alarm to locals and is only considering investing in a development.

Drones generally do not provide the same accuracy as a total station or GPS/GNSS. Position in x and y is sub 50mm generally but height is typically +/-75mm and this can be far worse depending g upon the terrain and payload the drone has.

Most drones employ photogrammetry to collect data and vegetated areas or areas below tree canopies will prevent data being captured. Lidar can also be mounted onto a drone. Lidar will penetrate vegetation allowing for the extraction of ground levels and contours. The height accuracy was generally not as good as terrestrial GPS/GNSS but can avoid a lot of environmental and ecological damage to collect data. The cost of employing lidar over photogrammetry with a drone is usually higher.

At Kemp we employ both payloads to collect survey data and are happy to advise of the optimum solution. Both techniques provide point clouds to enable 3d data to be extracted.

3D Scanner

Laser scanners can be either mounted on tripods, vehicles or handheld. Like drones scanners produce point clouds to enable 3d data to be extracted. Tripod mounted scanners are most typically used for measured building surveys and have accuracy similar to a total station but the ability to collect mass data. This usually requires extensive computer processing to enable topographic data to be extracted. Mounting scanners on vehicles or handheld typically dilutes the accuracy and hence is generally best employed for asset management and feasibility work. The projects need to be large generally though to make the employment of mobile mapping financially feasible.

Topographic surveys generally deal with features on the surface. On occasions however a developer needs to know what is below the surface.

Hydrographic Survey

A hydrographic survey maps the surface under a body of water. Specialist hydrographic firms deal with only sub-sea work. At Kemp we provide hydrographic surveys of relatively shallow inland or near shore beds. This is often in the form of a surveyor taking observations from a small canoe or dingy although occasional a remote-controlled boat with sonar will be employed for a more detailed mapping exercise.

Utility survey Buried services and utilities often complement a land survey and this is where our specialist utility surveyors at Seeka employ the latest GPR, CCTV and EML tools to map drains, services and utility mains.

What will I be given?

The deliverables and outputs available are vast. By default, a 2d and 3d CAD along with a PDF will be supplied by most firms and this is suitable for the majority of projects. 3d point clouds and models in formats such as Revit can also be produced if considered advantageous, and if the cost/benefit justifies such formats.

How do I know what type of topographic survey to ask for?

As we have discussed the question really is what do I need the survey for, and what level of accuracy or detail is required. At Kemp we like to work with you and encourage clients to tap into our vast experience of producing topographic surveys for the smallest and largest of projects and that are employed by everyone from work from home architects to multi-national consulting firms. An early conversation with our team that employ all of the above techniques daily will undoubtedly ensure that you have the optimum solution.

To conclude we are experts at producing topographic surveys we are a firm of RICS regulated chartered surveyors and our expertise is at your disposal to discuss your survey requirements. We have in house all of the latest instrumentation and technologies.

RICS 1:200 (band F) meets most needs.
Consider accuracy and detail required.
GPS - let the surveyor decide when it should be used.
UAV/Drone large areas, feasibility, lower accuracy, imagery produced, vegetation can be penetrated, discuss with the surveyor if suitable.
Laser Scanners provide mass data and point clouds to varying accuracies.
Hydrographic provides bed levels of lakes, ponds and near shore coastline.
Seeka trace and map services by specialist qualified surveyors.

Feel free to contact one of our friendly survey managers at either Exeter or Redruth to chat through your requirements.

Types of Topographical Surveys