How laser scanning is changing the way FAM Construction (Ferrovial – Allan Myers) collects site information on their roadway projects

Author: Frank Collazo

Washington D.C. has some of the worst traffic congestion in the USA. Along with relieving congestion, improving safety, and moving 2,000 to 4,000 more people hourly, this 22-mile roadway expansion project will transform this critical Northern Virginia artery by adding two additional express lanes, three regular lanes in each direction, interchange enhancements, toll roads, park and ride lots and shared use paths.

With the aid of 3D laser scanning, this project is changing the way FAM Construction collects site information, reports changes and insures everything is within design tolerances.

Said Gabriel Jimenez Lopez, FAM’s Survey Manager, “With scanning, I don’t have to imagine anything, it is a highly accurate 3D picture of the construction site sitting on my laptop, better yet, I don’t have to rely on someone’s interpretation of what they think is a break-line or an important feature, and best I don’t have to question if they picked up a critical piece of data. Everything is there all the time”.

Field Crew

2-person crew setting control with a Leica GS18 T, while placing the RTC360 3D laser scanner on a tripod. Total time per setup; 2 minutes 30 seconds.

Two scanning crews are each equipped with a Leica RTC360 3D laser scanner, tablet computer with the Leica Cyclone FIELD 360 app, Leica CS20 controller and Leica GS18 T GNSS smart antenna. They are standalone independent of other surveyors so no need for total station coordination and no need to plan where to set control.

Field Workflow

Consists of setting one control point with the GS18 T/CS20 at 30-second RTK mode per setup, then using Cyclone FIELD 360 app to scan at medium resolution and acquire HDR imagery: roughly 1 minute 51 seconds for scan and imagery. Basically, press two points in field, one on CS20 for control, the other on the Cyclone FIELD 360 app to scan, then rinse and repeat. Control is extracted in the office using auto-extract control during import.

When a project calls for higher accuracy, such as monitoring structures and steel, GNSS RTK control is supplemented with total station control.

Office

Scans are imported into Cyclone REGISTER 360 and checked. No need to register or geo-reference because this was done in field via the Cyclone FIELD 360 app. Simply import, check quality, adjust if needed, then export point cloud and use Cyclone 3DR for the many applications it offers. Weather it is checking verticality, auto-extracting ground to create TIN, volume calculations, creating cross-section reports, or checking as-built vs design, Cyclone 3DR covers all this for FAM.

In addition to topo’s FAM uses scanning for:

• Earthwork calculations
• Monitor retaining walls - check from week to week to ensure movement did not occur
• Bridge deck work for new and expanded bridges during build to ensure design tolerances are met
• Measuring stockpile volumes with high accuracy
• Checking verticality of H-piles (i.e. steel)
• Sharing data with other departments i.e. their Construction Technical Office over internet using TruView
• Watershed analysis
• Bridge clearance
• Check structural damage of existing bridges for repair

Watch video to see project in action.

Scan of retaining wall with control point

Instead of checking elevation and verticality against design one measurement at a time via total station, FAM checks hundreds of H-piles in minutes with RTC360