Airport Tarmac Inspection

Tarmac 3D modeling and deformation analysis of airplane roundabout loops / Athens International Airport “El. Venizelos” – Greece

Purpose

The airplane traffic at the Athens International Airport towards its 2 air-corridors (eastern and western) is regulated through 4 roundabout loops, 2 for each corridor. Due to the traffic load, the fact that the heavy aircrafts often have to stop at the loops and the type of the pavement, the tarmac at those 4 areas has developed noticeable deformations. So, the technical department of the A.I.A., in order to define the extent of the damage and decide what kind of corrective actions should be taken (from simple tarmac repairs to full pavement reconstruction), requested a detailed 3D modeling of the tarmac surface, followed by a complete deformation analysis. The methodology should combine a high level of detail (measurement every 2-3 cm), speed (each loop could remain closed only for a few hours) and accuracy (<1cm for elevations).

Project tasks

  • A 3D laser scanning survey, using the Optech ILRIS 36D Laser Scanner, was performed (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 was obtained using conic and circular targets, measured from the airport’s geodetic control points.
  • An aligned and georeferenced pointcloud for each area was created.
  • Sub-sampling (3cm) and triangulation of data points was performed, followed by an optimization and decimation of the model from 3 million triangles to less than 5000 triangles, with insignificant elevation information loss.
  • An elevation map (contour spacing 2cm) was generated for each area.
  • Cross sections were extracted based on the above models and deformations were properly detected, measured, demonstrated and presented in table reports.
  • Results have been evaluated by the A.I.A. technical department and different corrective actions have been decided for each loop area.

Results – Conclusions

Laser scanning has proven to be not only the most effective method for the project’s purposes, but in fact the only one applicable, offering the required resolution / level of detail and accuracy at a speed that was acceptable for the airports restrictions.

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Railway tunnel 3D survey

Railway tunnel survey and structural inspection, Aghios Stefanos, Athens – Greece

Purpose

The Greek Railway Organization main railroad, to its northern exit from Athens, passes through a tunnel complex, consisting of four tunnels (two for each railway line), near the small city of Aghios Stefanos. The NE tunnel, approximately 200m long and 5m wide, was built from stones about 50 years ago. Due to suspected deformations of this tunnel in combination with known geological problems of the whole area, the Greek Railway Organizations ordered a stability check, along with a complete survey of the tunnel and the superjacent ground.

Project tasks

  • Establishment of geodetic network (GGRS’87).
  • TLS survey with Optech ILRIS3D:
    • 8 scanning positions (6 inside – 2 outside)
    • Average resolution 1-2 cm
    • Georeferencing: 8 conical targets, additional control points
  • Conventional survey of superjacent ground surface above tunnel.
  • Basic processing of TLS data and other measurements.
  • 3D modeling of tunnel and superjacent ground, H and V section extraction.
  • Inspection in comparison to theoretical geometry.

Results – Conclusions

The cross-section based evaluation and comparison of the surveyed tunnel wall to its theoretical geometry revealed large deformations at specific locations (e.g. section 15). These locations have been defined and mapped in detail and repairing actions have been designed. Tunnel has been closed until repair works will be executed. Further geological investigation defined the reason of the deformations to be the presence of slate (sch) and clay (PT) formations at the tunnel’s area and the existence of a possible fault between them.

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ECOMED | Hello World!

The “Specialisation Process for the Ecoengineering Sector in the Mediterranean Environment (ECOMED)” project is an initiative to advance the specialization process on landscape bioengineering, and to generate new alliances and dynamics in the sector, within the Mediterranean region. Its specific objectives are:

  • To improve the design/calculation of Bioengineering Works
  • To generate a suitable vegetation database for the Mediterranean region
  • To improve the implementation/construction processes
  • To improve the definition and planning of the monitoring of the works
  • To improve the works analysis tools, to be more effective in restoration and rehabilitation.
  • To improve the contents of the training offered related to landscape bioengineering

So, the EcoMed project will enhance bioengineering works at the different stages and phases: design/calculation, implementation/construction, monitoring, and education/training. This will be accomplished by implementing applied research works from 2017 till 2018. These works include the selection of a set of bioengineering tools and projects within the European Mediterranean region to further study and analyze them.

This project that is co-funded by the ERASMUS + Programme of the European Union will generate new tools to improve the possibilities of intervening in the landscape through techniques and approaches of bioengineering, taking into account the particularities of the Mediterranean region.

Overall the consortium comprises of seven universities and seven companies distributed in eight countries throughout the European region with Universidad Politecnica de Madrid the coordinator. Astrolabe Engineering is among the 14 consortium partners.

For more information on the EcoMed project please follows us through the following social media:

www.ecomedbio.eu

twitter: @ecomedbio

Facebook: Ecomedbio-Erasmus+

Road safety 3D modeling

Road intersections survey and modeling for the design and evaluation of safety improvement measures / High risk locations all over Greece

Purpose

The project was assigned by the Maintenance Department of the Greek Ministry of Infrastructures, Transports and Networks in order to improve safety for high accident risk locations (mainly road junctions) all over the Greek road network and, in particular, to design and evaluate through video simulations the appropriate improvement interventions for these locations.

Project tasks

  • Selection of “high accident occurrence – reduced safety” locations by the Maintenance Department.
  • Laser scanning survey, using the Optech ILRIS 3D Laser Scanner, of the road intersection area for each location. Sufficient road length had to be covered in order to create driving video simulations, at least 200 – 300 m for each intersecting road. Required resolution was about 5-10 cm, with an accuracy of 5 cm. Scanner was placed on the roof of a vehicle or lifted by a lifting device. Approximately 10 scanning positions were required per location, with a distance between scans 50 – 80 m and 20% (maximum) pan-tilt base overlap was used.
  • Alignment and georeference of the pointclouds to create a single colored and georeferenced point cloud for the surveyed area. Georeference was performed using the scanning stations as well as conical targets, surveyed with GPS from state geodetic control points.
  • Vector drawings (feature collection) and orthophotos (directly from colored scanned points) were created as a background for design purposes.
  • Design of safety improvement interventions: additional lanes (including acceleration – deceleration lanes), vertical and horizontal signage, changes in traffic regulation, closure of secondary roads, etc. Design was performed in vector format and new road elements were modeled in 3D (as polygonal models).
  • Vertical signage modeling (necessary for proper display of traffic signs in 3D video simulations) was performed by creating a small VRML model for each traffic sign. Traffic sign pictures were overlaid on circular, triangular, etc, 3D surfaces and exported as VRML models. Standard traffic sign pictures were available, while digital pictures of non-standard signs (e.g. showing directions) were taken and photos were ortho-rectified based on the shape of the sign. Finally, new (according to the design) signage pictures were created using image processing software.
  • Editing – cleaning of the initial pointcloud was performed and polygonal models of new road elements, as well as signage VRML models, were imported in a single environment, to create the “as designed” total 3D model.
  • Video fly – through and driving simulations were created. Driving simulations (from all possible origins to all possible destinations) were generated by applying vehicle trajectories and calculating distances and video frame intervals to simulate movement with variable speed. The same video frame sequences were applied to “before” and “after” models to create comparative results.
  • Video simulations were evaluated by the staff of the Maintenance Department and the Local Authorities in order to approve the designed measures for construction or forward the design for further revision and improvement.

Results – Conclusions

Laser scanning has proven to be not only a fast data capture tool to provide accurate and complete survey background data for road design purposes, but also an easy and efficient way of creating “before / existing” and “after / as designed” colored video fly-through and driving simulations to easily compare and evaluate the efficiency of designed – proposed interventions, before their actual implementation.

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Bridge 3D Inspection

3D inspection and structural deformation analysis of Axios river bridge at Northern Greece

Purpose

Close to the city of Thessaloniki, in Northern Greece, the Patras – Athens – Thessaloniki – Evzoni (P.A.TH.E.) Motorway, which is the main from South to North road transport axis of Greece, crosses the Axios river, one of the largest of the wider Balkan area. The crossing occurs with two long bridges, each carrying one carriageway. The southern bridge was constructed first about 40 years ago, while the northern one is much newer.

The southern bridge is 780 m long with 25 spans, built from armed concrete and has begun to show noticeable damages through time. The Greek Ministry of Environment, Planning and Public works assigned a project to check the bridges efficiency. Within the frame of this project, a complete 3D survey and deformation analysis was required.

Project tasks

  • Establishment of geodetic network (GGRS’87).
  • TLS survey with Optech ILRIS3D:
    • 6 scanning positions (from newest bridge)
    • Average resolution 2-3 cm
    • Georeferencing: 6 scanning stations, 12 circular (d:50 cm) targets, additional “natural” control points
  • Conventional survey for remaining details (southern side).
  • Basic processing of TLS data and other measurements.
  • 3D features collection (deck geometry, piers, road level, etc).
  • Geometric evaluation and deformation analysis.

Results – Conclusions

To better evaluate the 3D deformations of the bridge components, the results were presented as a longitudinal section of all examined deck edges, as well as angular measurements for each pier along the 3 axis, to demonstrate possible pier rotation. The evaluation showed insignificant rotations for the piers, but surprisingly revealed considerable subsidence of all piers, except those which were founded in the river’s bottom. Different type of foundation was identified as the most possible cause for this problem. Corrective actions are being studied to prevent further damage and deformation of the bridge’s structure.

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