Olson & Nesvold Engineers (O.N.E.) is making their footprint in the world of HDS (High-Definition Survey) 3D laser scanning.  Currently, O.N.E. does not have the technology to collect the field data but has teamed up with other agencies that have the ability to supply it to us.  From there Dan Crawford (O.N.E. Principal Technician) is able to analyze the data.

HDS is similar to conventional survey in terms of setup but that’s where the similarities end.

• Conventional survey requires the use of a prism held at each point needed to collect the required data.
• GPS survey is similar in that it requires the collector to be manually held in position at each point needed.

Both methods are fairly accurate but a rather slow means of collecting data and nearly impossible if you require a highly detailed, accurate model of an existing structure.

This is where HDS has its benefits.  A 3D laser scanner collects data by firing a laser and information back to the scanner.  This method collects thousands of accurate points in a matter of minutes.

Once collected the 3D laser scanner can be moved to several different setup location to gather multiple points-of-view to later be combined (registered) into one common file.  The resulting file is a highly detailed representation (point cloud) of the structure scanned forever in time that can be viewed from any direction.

In a CAD (computer-aided design) world this is beneficial for several different reasons.  Each point collected has an X, Y, Z value assigned to it.  The days of needing to go out in the field, setup a ladder and try to get an accurate measurement of a structure are a thing of the past.

Point cloud models can be opened using a variety of software and manipulated to get any type of measurement, cross section, slice, etc., that you may ever need.  It is a great tool to have while working on historic bridge projects or structural rehabilitation projects that have, at best, minimal plans available.  You can slice and dice a point cloud model to get just about any bit of information imaginable (providing a highly accurate scan was made available).

Projects O.N.E. has used HDS on to date:    (Click to see more information about a specific project)

• Silverdale (Steel truss relocation project)
• 15^th Ave (Concrete bridge rehabilitation project)
• 16^th Ave (Concrete bridge rehabilitation project)

Benefits:

• Accurate representation of a structure captured in time (great for historic or monitoring purposes)
• Very useful for engineering (accurate measurements, slopes, fitments, etc…)
• Reduces or perhaps eliminates field time and return trips (everything is right there at your computer)
• Able to extract data not possible in the field such as bridge deck thickness (bridge deck would need to be cored through to measure thickness in field)