Multibeam and Laser: Combined High Resolution Hydrographic Surveying for Civil Engineering Project Support John Dillon-Leetch,Port of London Authority Duncan Mallace, NetSurvey, UK Overview Introduction to MBES capability Engineering Support Surveys : Identifying the Market Project Development Delivery Methods: Acquisition Processing Opportunities and Challenges Conclusions 1
Verifier Galloper YANTLET BRENT MBES Equipment 2004: Reson SeaBat 8101: Charting, Navigation Support Surveys London Gateway Dredge Support 2006: Reson SeaBat 8125 : Wreck Surveys, Archeological assessment, Business case Bridge Surveys Engineering Support 2008: - Reson SeaBat 7125 : Mobility, Access, Flexibility, Redundancy of plant Position fixing: : Applanix PosMV 320 Inertial navigation unit providing positional and orientation data. POSPac post processing to RTK Centimetric Accuracy Software: Hypack and Fledermaus. 2
MBES Boat Fits 8125 - Yantlet New MBES Vessel 2008 Transportable by trailer project or chartered work further from base. High Speed (28 knots) Shallow Draft 0.3m SBES, 1.1m MBES Moonpool for deployment. Tilting Head 3
Boat Fit: 7125 Moonpool Deployment 4
Berth Survey High Resolution. Scour System can measure depths beneath structures & vessels Controlling Depths Slope Stability Speed of survey 5 times faster than SBES resulting in little or no berth downtime Visualisation Capability Structure Monitoring-Scour Damage 5
Plan View Showing Undercutting Obstruction Detection XL-XS Standard Port use delivering high accuracy & repeatability. Extending this to vertical Structures involved quantifying achievable accuracies and deliverable results 6
Assessing the System Capabilities 8125: Could it do what it said on the tin? Civil Engineering Support Education of Clients Oceanology 2006 Baseline Surveying Structure examination Site Investigation Wall Condition Surveys: Pre/Post Works Free-viewing software methodologies Powerful Project support capability. Value Added particularly to non-surveyors 7
Dover: Quay Wall Survey Monitoring -2006 Client Specified detection of 1x1m granite blocks. 7000m of breakwater surveyed in two tides. Alternative/ traditional method 30 days diving Experimentation of amalgamation with other data sources. Multibeam data knitted to surface photography Proves system & makes data interpretation easier for non-surveying client. 8
Proving the System Canary Wharf: July 2007 Joint Venture with Engineering Diving Company Survey Specs : +/- 3cms in XY and +/- 7cms in Z. Identification of anomalies such as damage, cracks, distortions, abnormalities or other defects of +/-5cms in extent 99% correlation between MBES and Diver survey for all quay walls. Feature Information Feature ID: WWharf_021 Wall: Wood Wharf 5 Easting: 537961.44mE Northing: 180134.27mN Chainage: 65m Depth: 2.75-3.80m Recess: 0.10m Length: 0.20m Notes: Vertical recess in wall 9
Fledermaus - Processing Challenges High Resolution Data X-Sections Profile Information Profile ID: WWharf_P02 Wall: Wood Wharf 2 Chainage: 20m Gradient: 88 degs Notes: Wall in good condition. Profile Information Profile ID: WWharf_P05 Wall: Wood Wharf 2 Chainage: 119m Gradient: 92 degs Notes: This wall section is just to the west of the ladder and has severe damage to the top two-thirds with recesses of up to 0.4 m. The wall is also overhanging slightly at this point which might indicate that it is being pushed from behind. 10
Laser Scanning 2008 Riegl Laser mobilised to PLA survey vessel Galloper (Aug 08) Scanner was a Riegl Z240i which has a 500m range and scanned and registered using Riegl Riscan Pro Data was cleaned up in Pointools & Fledermaus Edit to remove stray points and false objects in the scans ( cars, boats, people, and filter data if necessary. Static scanning produces 10-15mm spacing on surfaces where possible. Boat based 5-10cms dependant on boat speed. Assessed PPK and tracking TS positioning control. Static Scanning of Survey Vessel System : Faro Photon2 Phase Based Laser 11
Laser Scanning Schematic Laser Data Examples Savoy Pier Scan Imagery Westminster Area Overview 12
Engineering Project Support (Hydrodynamic & Civil) MBES and Laser Surveys deliver:- Tangible Results. Powerful Project Support Capability. Safe & Non Intrusive methodology Augment or replace Dive Surveys Additional value added for Lidar augmentation for structural inspection, asset tracking, baseline survey data. Opportunities and Challenges 1000 s miles of inland waterways & crossings requiring surveying Tunnel Surveys? 40 miles of tunnels Prohibitive cost of de-watering Issues: Shallow Water <3m Surface reflections for laser and MBES MBES/Laser Interface data gaps. Can vessel based lasers provide engineering level of data. 13
CONCLUSIONS Performing surveys using multibeam technology significantly reduces the time it takes to inspect and survey dock walls. Data is collected at a much higher resolution than is possible using general diver surveys. There are much lower HSE risks associated than with Diver Surveys. Dock wall surveys can be performed at the same time as other dredge or charting survey activities and can form part of an annual inspection. Acquisition and fusion with Laser scaning data increases value added Accuracy, Precision and repeatability reaching structural survey levels 3D visualisation significantly enhances the products produced and aids the analysis and presentation of the data New Developments: Integration of Terrestrial Laser systems? Need to develop specifications for engineering level of surveys for MBES & Lidar surveys Any Questions? 14
At Work 15