Reality Computing

Laser Scanning vs. Conventional Surveying during Post-Construction

By: Community Manager | Posted ‎01-19-2016 01:46 PM , edited ‎01-26-2016 01:38 PM |

 

Several construction companies presenting at AU 2015 described how their firms are using Reality Computing in their construction processes. One of those companies was Balfour Beatty Construction. The AU class (RC10535: Real-World Applications of Laser Scans) was presented by Claire Mao, Rudy Armendariz, and Jenny Yuan. The company relies extensively on virtual design and construction (VDC) and Building Information Modeling (BIM) processes, and also uses Reality Computing to support its VDC/BIM workflows.

 

During the class, the Balfour Beatty Construction representatives used a case study to compare conventional industry standard survey techniques to 3D laser scanning for liability identification during post-construction. They described two specific construction tolerance concerns from a recent hospital project at Fort Riley, a U.S. Army base in Kansas. The two tolerance concerns were a ‘C’ channel member that was part of an eyebrow feature and a steel angle in a clerestory feature. Both the C channel and the steel angle were high above the ground and difficult to access, but required immediate attention to minimize schedule impacts.

 

                                                                                                    (Existing Environment Capture)

 

After describing the project and these two tolerance concerns, they then presented detailed cost breakdowns and schedule impacts for the conventional surveying of the C channel and the steel angle, versus 3D laser scanning. Their detailed cost and schedule breakdowns are at the end of this article, but here is the summary:

 

Industry standard survey:

 

  • The cost to capture the installed C channel: $29,300
  • The schedule impact: 16 days (potentially creating liquidated damages for the project)
  • The cost to capture the installed steel angle: $13,000
  • The schedule impact: 10 days

 

3D laser scan survey:

 

  • The cost to capture the installed C channel and the steel angle: $11,000
  • The schedule impact: 10 days

 

Combining these two efforts, the total cost using standard surveying was $42,300 and took 26 days. The total cost using laser scanning was just $11,000 and took 10 days (C channel and steel angle are captured during the same scan). Doing the math, the savings from using laser scanning is $31,300 and 16 days! As Balfour Beatty Construction concluded in the presentation, laser scanning is faster, costs less, provides greater accuracy, and is safer. A clear winner…

 

You can download their entire presentation from this link, which includes uses of laser scanning throughout the construction process. FYI, you’ll need a login & password to download material from au.autodesk.com, but you can get those for free just by registering at the site.

 

                                                                                                              (As-Built Design Assistance)

 

Detailed cost and schedule breakdowns for C channel capture

 

Industry standard survey:

 

  • 2 man crew for 8 days $9,600
  • Survey equipment $2,000
  • 150’ boom lift rental for 1 week $8,000
  • Boom lift operator (included in survey crew)         $0
  • Lodging / travel / per diem costs $3,200
  • Scissor lift rental $1,500
  • Scissor lift operator (included in survey crew)         $0
  • Detailer converts to CAD $5,000
  • Total cost (excluding schedule delays): $29,300

 

  • Survey time 8 days
  • Electronic conversion to DWG time 8 days
  • Total schedule impact: 16 days

 

Laser scan survey:

 

  • 2 man crew for 3 days $11,000
  • 3D laser scan survey equipment (included)         $0
  • Lodging / travel / per diem costs (included)         $0
  • Total cost (excluding schedule delays) $11,000

 

  • Survey time (including travel) 3 days
  • Scan registration and DWG deliverable 7 days
  • Total schedule impact: 10 days

 

Detailed cost and schedule breakdowns for steel angle capture

 

Industry standard survey:

 

  • 2 man crew for 5 days $6,000
  • Survey equipment $2,000
  • 150’ boom lift rental for 3 days         $0
  • Boom lift operator (included in survey crew)         $0
  • Lodging / travel / per diem costs $2,000
  • Scissor lift rental         $0
  • Scissor lift operator (included in survey crew)         $0
  • Detailer converts redline to CAD $3,000
  • Total cost (excluding schedule delays): $13,000

 

  • Survey time 5 days
  • Electronic conversion to DWG time 5 days
  • Total schedule impact: 10 days

 

Laser scan survey:

 

  • 2 man crew for 3 days $11,000
  • 3D laser scan survey equipment (included)         $0
  • Lodging / travel / per diem costs (included)         $0
  • Total cost (excluding schedule delays) $11,000

 

  • Survey time (including travel) 3 days
  • Scan registration and DWG deliverable 7 days
  • Total schedule impact: 10 days

 

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Comments
By: Community Visitor lassilapam
| Posted ‎02-28-2017 05:13 AM

Wow I didn't know that laser scanning could be a few thousand dollars cheaper! I am all about saving money wherever I can. Is there any difference between the two when it comes to what one is more effective/ efficient? http://www.monteathpowys.com.au/laser-scanning/.aspx

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