The document discusses using laser scanning technology to model highways, roads, and pavements for various applications. It describes three projects where laser scanning was used: 1) surveying an existing highway in Greece for reconstruction, scanning from a lifted device to capture horizontal features; 2) evaluating tarmac deformations at an airport, requiring high accuracy and resolution; 3) evaluating safety improvements at an intersection through 3D modeling and simulations. While laser scanning provides high accuracy and detail, it has disadvantages for long linear objects like highways due to lower productivity and need for significant post-processing. Mobile scanning systems may provide more efficient alternatives.

1. 3rd Annual
Optech ILRIS-3D Users Meeting
Rome, Italy - June 6-7, 2007
Efficient Road Mapping
Modeling of Highways, Roads and Pavements
using Laser Scanner Technology
Michael Xinogalos
Surveying Engineer NTUA
ASTROLABE ENGINEERING / JGC

2. Applications
• Highway survey and modeling (“as –built”
record, background for design and construction)
• Airport tarmac modeling and evaluation
(maintenance)
• Road intersection survey, design of
interventions to improve safety, 3D modeling
and integration, video simulations (evaluation
of proposed measures)

3. “Korinthos – Tripoli” Highway
• Location: Central Peloponnesos, Greece
• Self Financing Project: Construction of a new highway
section / Reconstruction and Maintenance of an existing
highway section – J/V MOREAS
• Existing Highway: Dual Carriageway, 2-3 lanes & shoulder

4. “Korinthos – Tripoli” Highway
Existing highway survey requirements
• Detail “as built” survey of all highway features (pavement,
structures, slopes, signage, poles, etc.)
• Efficient archiving of “as built” situation for future reference
• Positional accuracy of georeferenced points: 2-3 cm
• 3D model (TIN) for highway reconstruction design
• Background survey maps (scale 1:500)
• No traffic closure or delay
• Efficient safety plan
• Permits from local traffic authorities

5. “Korinthos – Tripoli” Highway
Project tasks (1/4)
• Establishment of geodetic infrastructure networks (triangulation,
leveling, polygonometry), also necessary for construction
• Static (stop & scan) laser scanning with Optech ILRIS36D
• Scanner carried by a vehicle moving or standing always on the
shoulder lane, protected by a traffic regulation trailing vehicle
• Scanning from both sides of the highway, distance between scanning
positions 50-80m

6. “Korinthos – Tripoli” Highway
Project tasks (2/4)
• Critical issue for horizontal objects: lifting the scanner (better scanning
angle, improved object visibility, lower scanning resolution and / or
fewer scanning positions required)
• Lifting device used: Genie Super Hoist (5.6m, 113 kg capacity, CO2)
• Custom modifications: Trailer integration, 5/8 bolt, longer ethernet and
power cables, stabilizers, fuel generator & UPS, etc.

7. “Korinthos – Tripoli” Highway
Project tasks (3/4)
• Scanning resolution: 55mm @ 25m horizontal / 20mm @ 25m vertical
• Pan-tilt base overlap set to maximum (20% overlap, 15 frames/3600)
• Primary georeferencing: with conic targets (standard traffic cones:
easy to install, measure and model), 1 cone (anchor point) per scan
position required for sequential georeferencing (Polyworks IMAlign -
IMInspect)

8. “Korinthos – Tripoli” Highway
Project tasks (4/4)
• Georeferencing refinement for elevations: using additional points
measured with GPS on the shoulder lane white lines every 50-80m
(Polyworks IMInspect)
• Feature collection from pointclouds (Polyworks IMInspect)
• 3D Modeling (TIN) from features and survey map creation (Autodesk
Civil 3D)
• Archiving for future reference: Subsampled pointclouds (5cm) per km
(Polyworks IMView)

9. “Korinthos – Tripoli” Highway
Point cloud vs TIN model / features

10. “Korinthos – Tripoli” Highway
Background survey map (scale 1:500)

11. “Korinthos – Tripoli” Highway
Background survey map (scale 1:500)

12. Athens International Airport
Evaluation of tarmac deformations at the 4 airplane
maneuver areas on either side of the E & W air-corridors

13. Athens International Airport
Survey requirements
• Positional accuracy: 1cm
• Resolution: 5cm
• Data capture for each area within 6 hours
• Tarmac 3D modeling
• Elevation maps (contour spacing: 2cm)
• Cross-section level analysis

14. Athens International Airport
Project tasks
• 6 to 9 scan positions per area (scanner on top of a car, tripod mounted),
20% pan-tilt base overlap, distance between scans <50m
• Georeference using conic and circular targets, measured from the
airport’s geodetic control points
• Creation of an aligned and georeferenced pointcloud for each area
(Polyworks IMAlign and IMInspect)

15. Athens International Airport
Project tasks
• Subsampling (3cm) and triangulation of data points (Polyworks
IMInspect), optimization and decimation of TIN model from 3 million
triangles to <5000 triangles (Polyworks IMEdit, IMCompress)

16. Athens International Airport
Project tasks
• Creation of elevation map (contour spacing 2cm) (Autodesk Civil 3D)

17. Athens International Airport
Project tasks
• Cross section based analysis (ODOS software), reports
• Evaluation of the results by the AIA authorities

18. Evaluation of safety improvement measures
in road intersections
Ministry of Public Works – Maintenance Department
Current intersection layout – orthophoto from pointcloud
Design of improvement measures – 3D modeling

19. Evaluation of safety improvement measures
in road intersections
Ministry of Public Works – Maintenance Department
General layout fly-through
Current layout Proposed layout

20. Evaluation of safety improvement measures
in road intersections
Ministry of Public Works – Maintenance Department
Driving simulation – Direction from Messolongi to Antirrio
Current layout Proposed layout

21. Conclusions
Static Laser Scanning can be an efficient road mapping tool for
projects that require:
• high accuracy
• significant level of detail
• total object recording for archiving and future reference
• 3D modeling and motion simulation
• safe data collection
Disadvantages:
• productivity for long objects (e.g. highways) cannot exceed 500 to 800m of
surveyed road per day (portability and scanning height are critical factors)
• significant post processing work is needed, decimation is required to export
data to transportation design software
Mobile scanning systems with improved functionality will
provide a much faster and efficient alternative in the near future

22. Any questions?
Visit: www.jgc.gr / www.astrolabe.gr