Today’s modern total stations have evolved into incredibly versatile and productivity-enhancing measuring instruments with many applications for the construction site.  However, other optical instruments have recently been introduced that can do even more in the specific applications they were designed for.  These new technologies are worth a brief overview and may very well impact your job site productivity and profitability.

Laser Scanners:
When it comes to collecting a large number of points quickly; laser scanners are the 800 pound gorillas in the room. Amazingly they can measure up to 300,000 three dimensional points per second.  They use special light beams to measure to surfaces without the use of reflectors. They are used extensively in plant and facilities management to obtain very dense and detailed 3D models of existing features.  They are also used by surveying and engineering firms to map and obtain as-built information on civil engineering projects.  Construction site applications include highly-detailed maps of existing structures. They are fantastic instruments when you need a lot of detail on elevated structures that cannot be accessed by a rodperson.  They can also be used in tunneling, mining and other situation where in is not practical to use traditional instrumentation and techniques. They gather huge amounts of point data, ranging in the millions.  The resultant data set is referred to as a “point cloud” and often requires modeling or other manipulations to arrive at a useable 3D or 2D product.  After initial setup, the instrument scans autonomously until the next instrument set- up is needed.  Laser scanners have recently also been integrated into mobile mapping solutions which may have construction site applications down the line. Manufacturers include: Leica, Trimble, Topcon, FARO, Optech, Riegl, Callidus, Maptek and Surphaser.

Monitoring:
When working in unstable soils or tunneling underground, monitoring of existing structures is often required by owners and public regulatory agencies. As many of these sites are in urban canyons, specialized total stations come into play. These are models with the highest angular accuracy (+/-0.5 seconds) and extremely high accuracy distance measurement (+/- 1mm or less). They can work in the reflector or reflectorless mode.  These total stations can perform very accurate measurements and, with clever software, can work autonomously after the targets are initially located.  As these instruments are robotic and can automatically aim themselves at the targets. The software can “wake up” the instrument at preset time intervals, measure to all targets of interest and perform analysis of any movement automatically.  These systems have been in use for years, measuring the direction and magnitude of movement (over time) on dams (deformation studies), roadways, high walls in surface mines (slope monitoring) and on other projects where the stability of existing structures and surfaces is of concern. These total stations can also be used for other surveying and layout tasks.  Some models include photographic or video capture capabilities as well.  Leica, Topcon and Trimble are suppliers of such systems.  Product specifications and system software capabilities vary.

Imaging and Spatial Total Stations:
Combining the best features of robotic and reflectorless technologies with imaging and video capabilities has resulted in a new breed of total station.  Sort of the “Ultimate Driving Machine” of optical instruments. Trimble’s VX Spatial Station and Topcon’s IS Imaging Station are amazing in their integration of technology and versatility.  They can be used as regular robotic total stations for layout and data collection.  They can also be used as an alternative to laser scanners.  Operating autonomously, these units can scan up to 20 points per second at longer ranges than most laser scanners.  Photographic and video capability is added for remote control and documentation/verification purposes. I think that these instruments would be very useful in quality assurance efforts. They can be used for monitoring, scanning and all other tasks that a reflectorless robotic total station performs.  The capabilities and specifications vary somewhat but software is probably the ultimate differentiator, so checked them both out.

Mobile Mapping Systems:
These systems are relatively new, and incredible in what they can do. Integrating GNSS, inertial guidance systems or inertial measurement units (IMU), 360 degree digital cameras and laser scanners they can map their surrounds at highway speeds.  The speed part amazes me.  This is revolutionizing Geographic Information Systems (GIS) work and in some cases roadway mapping and maintenance. At the 2010 World of Concrete, Topcon suggested that their IP-S2 Integrated Positioning System could also be used for as-built surveys on construction projects with centimeter-level accuracy. Imaging determining earthwork quantities by just driving over the subgrade on a daily basis. That would be extremely fast and labor saving!  As all data is geo-referenced, measurements can be repeated over time to determine progress and translated into your project’s coordinate system.   Providers of such systems include: Optech, Applanix, Topcon and Riegl.

Conclusion
The decision whether to purchase one of the technological wonders or asking your local consulting surveyor to deploy them on your behalf will depend, in large part, on how often you will need them to accomplish your goals.  However, understanding their capability and availability may alter the way you approach special challenges and situations on the job site.

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