Proper construction of aggregate base courses is essential to assuring a high-quality finished surface for synthetic turf athletic fields, paved running tracks, and paved sports courts. Defects in the underlying construction will be reflected in the finished surface, resulting in athletic facility surfaces that have undulations, inconsistent surface planes, and varying cross-slopes. The finished surface product often represents the most significant portion of the project cost, requires strict tolerances to meet athletic performance requirements and the regulations of sports’ governing bodies, and is the finished aesthetic on which sports facilities are inevitably judged.
To ensure high quality finished surfacing, determining the acceptability of the base construction is a crucial step in the construction of synthetic turf athletic fields, running tracks, tennis courts, and sport courts. So, how do you assure that the base course has been properly installed in accordance with the tolerances specified for the athletic venue? In short…via field quality control measurements.
Historically, field quality control measurements have taken three forms: straight edge, string line, and field survey. Even when all three are employed simultaneously, human judgment, visual interpretation, and the “grid” spacing for field surveying can lead to areas of non-compliance that can easily be missed, leading to a substandard installation of the base course. For example, areas of undulation, depressions, or other surface deficiencies may still exist between the field survey shots comprising the grid, even at a ten (10) foot grid interval. Moreover, traditional “as-built” surveying can result in time delays relating to scheduling and completing the field work, downloading the survey data to prepare a scale drawing for review, and interpreting the data for compliance.
As a leader in the planning and implementation of athletic venues, ELA Sport recognizes that innovative technologies can overcome the above “technology lag” of traditional visual observation and surveying methodologies. Working with our subsidiary surveying company, Land Grant Surveyors (LGS), we have been able to measure the precise tolerances and acceptable variances required for aggregate and paving base construction for athletic facility surfacing in real time, by the use of 3D Scanning and High-Definition Surveying.
ELA Sport and LGS successfully employed Leica ScanStation laser scanners to verify as-built aggregate sub-base and pavement base for synthetic turf athletic fields and running tracks on several projects, beginning in June 2010. As a significant advance over popular “total station” survey instrumentation, the ScanStation includes a laser scanner for as-built topographic surveys. The advanced capabilities provide up to a maximum 50,000 points per second instantaneous scan rate with elevation accuracy of 6 mm and distance accuracy of 4 mm for all scan points.
When applied to quality control verification of athletic facility base construction, the laser scan technology provides the following advantages over traditional verification methods:
- The scanning technology provides digital terrain modeling as opposed to point-by-point elevation data. The terrain model creates a detailed record of the actual surface as opposed to point-by-point information. Consequently, judgment, interpretation, and interpolation are removed from the evaluation process and are replaced by quantitative data.
- Data acquisition time is reduced by over 75% as compared to traditional field surveying. Due to the instantaneous scan rate available with the ScanStation, thousands of points can be scanned instantaneously as opposed to surveying each point in the field individually.
- When connected in the field to a laptop computer, almost instantaneous feedback can be provided to the venue’s Owner, athletic facility consultant, and contractor. Delays associated with downloading survey data, preparing scaled drawings, and “in-office” evaluation can be virtually eliminated.
- Within 24-hours, the field data can be presented in a color-coded 3D topographic model that can easily be compared to the design profile for the athletic facility surface, allowing for ready comparison of the as-built condition versus the specified design. Areas of deficiency requiring correction can be readily identified and the volume/area of material required for correction can be quickly determined.
- With the real time ability to correct base course issues and by eliminating “data gaps” common in visual or traditional survey verification, corrections requiring cutting and patching of the finished synthetic turf or running track surface can virtually be eliminated.
- The time for data collection, visual field verification, and data analysis can be dramatically reduced resulting in cost savings for the quality verification process all while providing more accurate and relevant results. Further, considering the reduction in post surface installation repairs, overall project costs and construction delays can be eliminated and a higher quality finished surface can be provided.
ELA Sport continues to work with LGS, field and facility contractors, and our clients on the application of 3D laser scanning for as-built base course verification for a variety of athletic facility surfaces.
ELA Sport has employed this new technology on several of our athletic field and track projects during the summer 2010 construction period with positive results and feedback from our clients and athletic facility builders. Notable projects included survey of the resilient base layer at Villanova University, aggregate base surveys at Crispin Stadium for the Berwick Area School District, Seth Grove Field at Shippensburg University, and the new stadium field at Warwick High School.
ELA Sport continues to incorporate this advanced survey technology as part of our construction review process and is working to make the highest standard of base quality evaluation both easily available and cost effective, for venues ranging from the professional facility level to youth recreational sports facilities.
For more information about Land Grant Surveyors, please visit them at landgrantsurveyors.com
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