Continuing changing environment and increasing population bring the need to construct more buildings and renovate existing ones – we can see the change easily by looking at the streets.
Infrastructure, specially utilities, must be maintained or repaired continuously. The main challenge for this change is not knowing the accurate position of the utilities. Without knowing the accurate position of utilities, we can’t plan them. This brings the need of detecting and mapping utilities. The quality of detection and the maps is very important – if the location of the utility is wrongly detected, or if the utility cannot be detected, this can lead to hazardous accidents and damages. In order to protect people and assets, the quality of detection and mapping must be ensured.
Although there is no requirement for utility detection, associations try to ensure the detection quality by issuing guidelines. According to The Survey Association (TSA) in the United Kingdom, there are six levels of quality in utility detection that give a reference for surveyors and project owners to have a common understanding of what type of survey will be provided for each level. As you will see, each level requires tools or sources to locate utilities, based on the type of tools and sources the quality of the detection increases as the Level increases.
Level 1 – A desk top search of utility company records with the results consolidated onto base mapping.
This survey type is the most used in general and it can be provided for free or with a low cost, however, it only shows known utilities without accurate location or coordinates. Also, it is not possible to see old utilities and utilities crossing each other. This is, though, a good source to start with as it gives the type, size and direction of the utilities.
Level 2 – Using just an Electromagnetic Locator (EML) search in active and passive modes with located utilities being marked out on the ground surface only.
EML devices can detect metal services such as power cables of metal pipes. By using Leica Digicat or Ultra Locators you can pin point the power cables or metal pipes. Level 2 surveying is ideal for avoidance applications where the services will not be mapped. By using only EML devices, it is not possible to detect nonconductive lines such as concrete and plastic pipes or fiber optics. If you would like to get more detailed information about Passive and Active mode of EMLs please read our blog post “How cable locators work – Principles of buried utility detection.”
Level 3 – A Level 2 survey but the results plotted onto digital base mapping in CAD.
For Level 3 you can either mark the detected utilities on the surface and collect the points later with a positioning device such as a Leica total station or Leica GNSS antenna, or you can connect your Leica Digicat or Leica Ultra with Zeno 20 GIS Collector and collect points from detected power cables using DX Manager Mapping Utility Mapping Solution.
Having service lines digitally mapped makes the planning for renovation more efficient and saves construction costs.
Level 4 – A Level 3 survey but with lifting of manhole and inspection pit covers, recording the contents and noting tracing the lines of pipes and ducts using sondes or tracing rods. Results are digitally produced in CAD.
Opening manhole covers will give you information like type, dimension and material of the utilities. Although it will provide the start and the end point of service lines between two manholes, the status in between will remain unknown. This is also a very time consuming step. With Leica Digitrace, Digimouse and Maxisonde you can, nevertheless, trace the lines after opening the manhole covers. Results can be easily recorded digitally in DX Manager Utility Mapping cloud-based solution.
Level 5 – A Level 4 but with a predefined percentage of the survey area covered with close-centred recorded radar transects. This radar data is post-processed and interpreted at a later stage for incorporation into digital mapping along with the Level 4 data.
Ground Penetrating Radar (GPR) technology is used for detecting underground utilities. The main advantage of using GPR for utility detection is being able to detect nonconductive materials too. With Leica DS2000 Utility Detection Radar, you can detect concrete and plastic pipes or fiber optic cables beside services with conductive material. Post-processing is a critical part of using GPR for utility detection as it requires user interpretation for converting radar data to utilities. Leica DX Office Vision is an easy to use post processing software to digitally map utilities in an efficient way.
Level 6 – A Level 1 and Level 5 survey combined but with 100 per cent coverage of the survey area and close-centred recorded radar transects.
In addition to Level 5, Level 6 entails 100 per cent coverage of GPR detection of the area. This is the highest level of survey
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Written by Anabela Ferreira Fernandes, Marketing Communications Manager at Leica Geosystems