LiDAR AT PennDOTMichael Loose, C.P.

BOPD – Photogrammetry and Surveys

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I. What is LiDAR?II. Benefits of LiDARIII. PennDOT Case StudiesIV. Best Practices/Lessons LearnedV. Questions

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LiDAR for Engineering(LIght Detection And Ranging)

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LiDAR Photogrammetry

Airborne LiDAR

Mobile LiDAR

Static LiDAR

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Airborne LiDAR

PAMAP (PASDA)

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Static LiDAR (Terrestrial LiDAR)

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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

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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)

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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)

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Static LiDAR Projects:Bridge Emergencies (continued)

Static LiDAR:Schuylkill River Bridge, Hamburg

As-Builts for Widening (continued)

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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)

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 clearanceo Recorded beam condition

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Integrated Topo – Mobile LiDAR

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• 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

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SR 84 Section 282:Replacement or Rehabilitation of Three

Structures and Widening to Three Lanes in Each Direction

Fort Pitt Tunnel – District 11Safety for Surveyors, No Lane Closures

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• 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.

Cross Sections

Point Cloud View

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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

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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

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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

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Lessons Learned Best Practice

Everything Starts witha Ground Survey

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 Ortho-photos

Discuss special requirements ahead of time

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Lessons Learned Best Practice

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Mobile LiDARSingle 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!

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