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Your experience with utility accuracy?  

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Norman Oklahoma
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It is possible to detect and locate underground utilities within inches if it is a) a conductor, or buried with one, b) not too deep, and, most importantly, c) the operator is both knowledgeable and motivated. What you get with a one-call service is a crap shoot in that last department.  

I have seen water system locators show up with dowsing rods, and nothing else.  I know that some of you believe in that. I don't.  

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niko23
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With everything you've found on a principle level, I agree. I am concerned mainly with the fact that the data in the records (GIS) is extremely poor.

In the UK alone, there are millions of miles of underground utilities with often inaccurate, incomplete, or non-existent location records. It is estimated that the total length of utilities in the US is in excess of 56 million kilometres. More than half of the existent utilities in the US does not have a known horizontal position in the area. Underground utility infrastructure is inadvertently struck every minute in the US, equating to nearly 500,000 annual utility strikes. The societal cost associated with utilities damage in the US in 2016 is estimated at $1.5 billion. That is why a systematic improvement of GIS data is necessary, based on the criteria of integrity and reliability. The investigated study showed a positive return-on-investment ranging from US $2.05 to $6.59 for every dollar spent on improving underground utility location data.
Stakeholders In the UK require horizontal position errors to be less than 10 cm and definitely no higher than 30 cm. The allowable position errors are guided by ASCE 38-02 from the USA, AS 5488-2013 from Australia and ICE PAS 128:2014 from the UK standards. These standards categorise the GPR method as the second-best quality level. The ICE PAS 128:2014 sub-divides the accuracy into horizontal and vertical accuracies as a function of the detected depth. The best horizontal accuracy is ±15 cm or ±15% of the detected depth, whichever is greater, whilst vertical accuracy is ±15% of the detected depth.
 
I have been wondering for a long time if it is possible to achieve such accuracy with the GPR method...
I started to test the GPR method and get really interesting results ...
What is your GPR experience?
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jflamm
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Mapped a lot of utilities at my previous employer.  The mapping standards were Level A = potholed and/or exposed for direct measurement.  Level B = hooked on tracer wire or at the box, located and painted, measured.  Level C = just surface located by a locator such as Dig-Rite.  Level D = took info from old utility maps.   It all depended on what the client wanted. 

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Norman Oklahoma
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Those levels you refer to are from ASCE Specification 38-02, Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data

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niko23
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I started to test the GPR method and get really interesting results (find it on google)...

Journal Article published 19 Jun 2019 in Remote Sensing volume 11 issue 12 on page 1457

Kinematic GPR-TPS Model for Infrastructure Asset Identification with High 3D Georeference Accuracy Developed in a Real Urban Test Field

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Jaccen
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(@jaccen)
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World class examples have been done by the Japanese with GITA/ROADIC and Calgary off the top of my head.  I would use them as examples for any proposals.

 

https://geospatial.blogs.com/geospatial/2008/11/gita-japan-critical-infrastructure.html

https://www.calgary.ca/CS/IIS/Pages/Mapping-products/Mapping-Products.aspx

http://smartgrid.epri.com/doc/2014-06-24%20-%20GIS%20Interest%20Group%20-%20Geolocating%20Undergroud%20Utility%20Infrastructure.pdf

https://www.fgdc.gov/organization/coordination-group/meeting-minutes/2004%20meeting%20minutes/april/ROADIC_Final_Report.pdf

ROADIC expected accuracy (no idea if they have achieved that yet) 

"+/-10 to 20 cm"

Older PBOnline article about mapping it:

https://www.pobonline.com/articles/98346-d-mapping-of-underground-utilities

 

I was hired as a research assistant during my time at university to write up a report on the feasibility of acquiring or starting up a municipal division for Subsurface Utility Engineering (SUE) data for the City of Toronto.  Cost-wise, it would have made sense.  However, you had to convince city council to pay for it first to realize the benefits.  It was then shelved (circa 2006).  No idea if they are re-exploring the idea.  One of the main reasons they were initially interested was due to an old Bell telephone substation that was converted to a restaurant over time.  People "forgot" about all the lines running into.  Construction happened on the Lakeshore Blvd---bam---TSX shut down for a few hours.  Lots of people less than happy.

 

 

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