HDS Laser Scanning Project Experience
Disch-Faulk Field Baseball Stadium
As-built Survey
SH 164
MSC Bridge Wall Scans
FM 973 Bridge at Colorado River
Loop 1604 / US 281
HDS Laser Scanning of Bridge Structures & DTM
IH 35 Northbound, Riverside Drive to Town Lake
HDS Laser Scans of Main Lanes
Disch-Faulk Field Baseball Stadium
HDS Laser Scans for As-built Survey
SAM, Inc. provided HDS services to produce an as-built survey of sixteen (16) steel support beams in support of renovation/additions to the Disch-Falk Field baseball stadium for the University of Texas at Austin (UT). Our task was to capture, model and provide 3D positions and dimensions for the existing steel framework of the stadium to be used to fabricate new steel structures offsite. These structures would be transported and “bolted up” to the existing steel with virtually no project-site modifications necessary. SAM, Inc. used HDS/Cyclone© to collect scan data and model each steel support beam to include; angle of beam under bleachers, angle of roof support, and top/bottom elevations of vertical portion of beam. Lower support beams were also modeled to determine centerline coordinates for calculation of distance between spans. The front of the existing box office building was also located.
The final deliverables were in the hands of the client. five days after notice to proceed. They included an ASCII point list of all extracted positions, an Autodesk© Land Desktop 2006, a DWG file containing the solid modeled steel structures and dimensions, as well as a report for each of the 16 structures detailing upper and lower beam angles. In addition, the Cyclone© point cloud database and viewer were provided to the client allowing them to view the final dataset. The reports included a screen shot from Cyclone© showing each requested dimension and 3D position for each of the 16 steel structures.
SH 164
MSE Bridge Wall Scans
Problem: A highway bridge built over a haul road on private land belonging to a large mining operation presented a challenging situation for the TxDOT Bryan District . Because the bridge was constructed on reclaimed land, TxDOT had concerns about its stability. Engineers needed a full, detailed model of the bridge, including all critical measurements as well as a method to monitor movement or shifting over time.
Solution: Using the Cyrax 2500 3D Laser Scanner, the SAM, Inc. High Definition Surveying™ team created a precise as-built model of the complex bridge structure. Setting up the scanner at multiple locations, teams scanned the bridge and 2 retaining walls, each approximately 150' long x 35' high for the baseline survey. Prior to the first scanning session, SAM, Inc. teams affixed 3” x 3” plastic targets on or near the walls. The targets, in conjunction with other immutable bridge features captured during the scan, insure accurate relative referencing for subsequent scanning sessions. The on-site laptop collected dense “point clouds” of data, creating a 3D visual model of the bridge. Complete data collection was accomplished in 4 scans over a single afternoon, with no repeat visits to the site.
Technicians imported data sets of filtered point clouds into MicroStation/GeoPak. The data then populated GeoPak.TIN files required by the client. Data sets acquired in future scans will be compared and analyzed for variance from the 3D base model with precision and efficiency not available using traditional surveying or visual inspection methods.
FM 973 Bridge at Colorado River
Problem: Design engineers needed an as-built survey of a 500' long highway bridge to include a full detailed model of the bridge with all critical measurements in order to design a new bridge that would be built in near proximity to the existing bridge.
Solution: Using the Cyrax 2500 3D Laser Scanner, the SAM, Inc. High Definition Surveying™ team created a precise as-built model of the complex bridge structure. Setting up the scanner at multiple locations, field crews scanned the bridge. Prior to the first scanning session, SAM, Inc. teams affixed 3” x 3” plastic targets to guard rails and bents. The targets, in conjunction with other immutable bridge features captured during the scan, insured accurate relative referencing for registration of scan clouds. Using a laptop with wire-less modem capabilities, the SAM, Inc technicians collected dense “point clouds” of data, creating a 3D visual model of the bridge. Complete data collection was accomplished in 4 scans over a single day, with no repeat visits to the site. The scan data was registered to project control and incorporated in to a conventional topographic survey data set.
Using MicroStation/Cloudworks, technicians used filtered point clouds to produce a schematic drawing of the bridge deck and support structures referenced to project control. The data was seamlessly integrated into the topographic survey data files.
Loop 1604 / US 281
HDS Laser Scanning of Bridge Structures & DTM
HDS Laser Scanning - Bridges
A portion of this project included proposed widening and replacement of existing bridges. These included structures at cross streets along US 281 and Loop 1604 and the main lane and frontage road structures at the existing interchange. Survey information at the edge of and cross slope of bridge deck, face of abutment backwall, centerline of each bent, inside edge of top of deck at 1/5 point intervals on each span, bearing seat elevations and centerline of existing bridge columns was requested.
SAM, Inc. provided sub centimeter level accuracy for all requested information by capturing the data using HDS. Once captured, the hundreds of laser scanned data points that comprised the planar surfaces of the desired objects were modeled and intersected to create vertices at the requested location with a much higher level of accuracy and precision than if located by any other available means. Horizontal and vertical positions at these vertices were extracted; feature attributes were attached and exported as an ASCII point list. In addition to providing the requested survey information, the entire bridge structure at each location was scanned. This allowed the capture of additional survey data for later use without the need to revisit the site in the field, which would negatively impact the project schedule.
HDS Laser Scanning - DTM
Roadway DTM survey information was needed for the existing portion of the US 281 mainlanes at the tie in of the proposed direct connectors. Approximately 10,500 linear feet of northbound and southbound mainlanes and frontage road of US 281, and an additional bridge structure were captured using the Leica© HDS3000 laser scanner with no lane closures, disruption of normal traffic flow, or occupation of the roadway by survey personnel. Individual scans were registered together based on project control to create a georeferenced point cloud dataset. Using this dataset, breaklines and mass points were developed and exported. These features were imported into a Microstation DTM file from which a triangulated irregular network (TIN) was produced with sub centimeter level accuracy.
IH 35 Northbound, Riverside Drive to Town Lake
HDS Laser Scans of Main Lanes
Problem: Highway engineers suspected that the super-elevation along a vertical curve of the northbound main lanes of IH 35 had flattened to the point that driving conditions had become hazardous. They rejected conventional surveying solutions because of heavy highway traffic that created a dangerous work environment. A safe, non-intrusive method was needed to survey approximately 3100 feet of roadway and produce cross-sections at 50-foot intervals. Laser data needed to be tied to project control.
Solution: In this case, High Definition Surveying™ offered the safe, efficient solution that the engineers were seeking. Setting up the Cyrax 2500 3D Laser Scanner in locations away from traffic, the SAM, Inc. team scanned the roadway in incremental sessions. Targets were strategically placed to insure accurate relative reference and were surveyed using a reflectorless total station. The roadway was scanned with 0.20 foot grid spacing. A “point cloud” of precise data, stored on a laptop computer on site, was collected in multiple scan sessions.
The point clouds created a precise visual model of the roadway surface. The data sets were registered and filtered using Cyra Cyclone software. The data was then imported into MicroStation/GEOPAK, and GEOPAK.TIN files generated. Using an alignment provided by TxDOT, a SAM, Inc. laser technician imported the alignment data into GEOPAK and then cut cross-section at intervals of 50 feet. Cross-sections began at the center median and extended across the inside shoulder, the 3 main lanes, and ended at the outer edge of the outside shoulder. Paint stripes were also modeled from the laser scan data set.