LiDAR AT PennDOT Michael Loose, C.P. BOPD Photogrammetry and Surveys 2
I. What is LiDAR? II. Benefits of LiDAR III. PennDOT Case Studies IV. Best Practices/Lessons Learned V. Questions 3
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LiDAR for Engineering (LIght Detection And Ranging) 5
LiDAR Photogrammetry Static LiDAR Airborne LiDAR Mobile LiDAR 6
Airborne LiDAR PAMAP (PASDA) 7
Static LiDAR (Terrestrial LiDAR) 8
Static LiDAR AT PennDOT PennDOT was the first DOT to adopt the new technology in 1999 First big project was completed in 2000 Used primarily for smaller projects where high levels of detail are required, or safe capture of topos too dangerous for traditional survey
Mobile LiDAR 10
Sensor Configuration
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Mobile LiDAR AT PennDOT First project completed in 2010 Conducted a test to validate Mobile LiDAR in 2013 Resulted in a research paper and a national magazine article Led to replacement of other technology
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LiDAR Benefits (continued) 16
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Static LiDAR Projects: Bridge Emergencies Birmingham Bridge Dysart Bridge Paxton Street Bridge I 81 Bridge Fire 18
Static LiDAR Projects: Bridge Emergencies (continued)
Static LiDAR Projects: Bridge Emergencies (continued) 20
Static LiDAR: Schuylkill River Bridge, Hamburg As-Builts for Widening (continued) Due to complexity of the survey, Static LiDAR was completed in 270 hours versus the conventional estimate of 720 hours (which would also have required bridge cranes) 21
Static LiDAR: Inaccessible Areas SR 28 Allegheny County: Unstable cut/inaccessible SR 239 Luzerne County: Merged with Photogrammetry SR 2002 and 3023 pipe archs SR 6 Bradford County: o Calculated clearance o Recorded beam condition 22
Integrated Topo Mobile LiDAR Over 30 projects completed. Approximately 20 projects combining ground survey, Photogrammetry and Mobile LiDAR Requires planning ahead Includes photo products/orthos I84-282 is a great example and actually used all four technologies discussed including Static LiDAR 23
SR 84 Section 282: Replacement or Rehabilitation of Three Structures and Widening to Three Lanes in Each Direction 24
Fort Pitt Tunnel District 11 Safety for Surveyors, No Lane Closures Point Cloud View Cross Sections Survey for designated historic structure High traffic volume Very few shadow areas. Scan of entire tunnel structure prior to removal of ceiling Arranged for stoppage of traffic for only a few minutes to allow for mobile LiDAR scan vehicle to proceed without traffic interference. 25
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Lessons Learned Best Practice On smaller projects where data must be captured In difficult to access areas (slopes, tunnels, structures etc.) In unsafe areas (high traffic or steep terrain) In very high detail Static LiDAR may be helpful Contact your Survey Chief Photogrammetry and Surveys may complete the request or oversee man-hours and quality of data from provider 27
Lessons Learned Best Practice Mobile LiDAR is not always necessary. If: o High levels of accuracy o Safe roadway collection o High levels of detail are required, Mobile LiDAR may be necessary Other technologies may satisfy project requirements Get your Survey Chief involved as early as possible to determine what is really necessary 28
Lessons Learned Best Practice Requires primary control every ~800 using GPS for horizontal and differential leveling for vertical R.O.W. baseline must be established conventionally Drainage must be captured conventionally Get your Survey Chief involved as early as possible to control and schedule these activities Everything Starts with a Ground Survey 29
Lessons Learned Best Practice Data is only accurate to about 30 feet from the corridor Data is unreliable on downslopes Data is line of sight and vegetation will be collected Many features helpful to the designer may not be collected from the clouds Get your Survey Chief involved as early as possible!!! The best topographic map is one collected from multiple sources. Photogrammetry and Orthophotos Discuss special requirements ahead of time 30
Mobile LiDAR Single Best Practice Look ahead on the TIP or other sources for upcoming projects to determine well ahead of time what projects may benefit from mapping Work with your Survey Chief to determine what is needed Your Survey Chief and, if needed, the Photogrammetry and Surveys Section will plan a mapping project to be completed BEFORE your project goes to design! 31
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