Use of Mobile Laser Scanning Complexes for Precise

Determination of the Beam Gradient by Metal Bridges

8th FIG Regional Conference

Surveying towards Sustainable Development

Weser bridge Dreye Strategic infrastructure for the german railways

(Track number. 2200, km 229,2 - 229,8)

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Weser bridge Dreye 1927 construction Hamburg-Bremen-Köln-Venlo

1870-73 Weser as natural barrier

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Content1 Comparison of the data aquisition methods for bridge sleepers exchange1.1 Classic method1.2 Data aquisition with laserscanning based multisensor system

2 Steps for data aqusition and calculation using laserscanning2.1 Geopositioning of the multisensor system2.2 Detection of the bridge beams2.3 Processing of the kinematic scans with SiRailScan2.4 Automated generated register of the sleepers with Verm.esn

3 Impression from the building

4 Summary / Conclusion

Comparison of the data aquisition methods for bridge sleepers exchange

1.1 Classic method levelling the horizontal steel beams (as follow named beams) of the bridge frame. The results are heights relative to the benchmark consoles Tachymetric detection of the beam edges

Traditional method used till 2011-characteristics

Average daily output (8h) with classic method:250 sleepers

Average processing performance (geodetic data total station and leveling) of the measurement :300 sleepers per day

Classic measuring method

time consuming process to record the beams and random mounted bearings (x,y,z) at the right location cost for SiPo (safety personal of DB AG) and accommodation of the surveyor team. One troop 4 people with 2 hours frequency of exchange looking in both directions 500m with walkie-talkie ~1000 EUR/day + min two people surveyors

Few after work processes, if a hierarchic number system is used during the measuring process

Potential difficulties to detect measuring errors (polar

tacheometric measuring design without control)

Slight graphic documentation of the measuring

data, the beams are represented with 4 points

Non homogeneous information about the beam surface

1.2 Data aquisition with laserscanning

multisensor system with integrated laserscanner capturing of the whole beam shape (surface heights and edges) in one run via 3D technique objects that prohibit the seeing of the laserscanner has to be removed if necessary (for instance the security plates)

Laserscanning method

Average daily output (8h) with laserscanning method :3000 sleepers

Average processing time for the captured data :200 sleepers per day – based on the current status of automatization!

2 Steps for measuring and analyzing with laser-scanning

2.1 Geopositioning of the multisensor system

Rail transition to the bridge

Positioning of the scanner above the rails resp. beams

Defining the position of the scanner each 20m via tachymetric free station

based on 4 bechmarks (mounted prism adaptors with constant offset)

Simultaneously scanning the benchmark points of the

track (GV) marked with spheres

2.2 kinematic laserscanning of the bridge beams

Multi sensor system to scan based capturing of the environment

Measurement performance - 2 km/h

Short times of track locking

Optional: the system could be lifted out

of the rails within 8s, (horn signal)

a complete locking of the track is not a must

For this bridge it was not possible

Each day of surveyor work on the bridge is a

big safety risk!

2.2 kinematic laserscanning of the bridge beams

2.3. Processing of the laser scans with SiRailScan

• Georeferencing and synchronizing the scans

• Cutting out the detected beam geometry

• Calculation of the beam heights

Example for a structure change

Structure changeHeight based color coded beams: scan overview:

Hidden by the sleepers

Milled out sleeper

If an 4 cm height difference on the steel beam surface is detected a sleepers milling is necessary cmiling m

Bearing with plates

An automated algorithm is searching for the heights miling m

Transversal beam with plates

• The coloring of the heights of the beams relieved the control an the detection of the plates (height differences)

• The standard height on the steel beam is blue, the plates are colored green

• The height differences are approximately 1,5cm

• Correspondingly the milling for some sleepers has to be adapted

Milled out sleeper with plate - puzzle numered sleepers Nürnberg

Approximated fitted height with plates – milling is still needed – 2 cm plates

Corrosion protection damaged – source for outliers by the levelingRail force bearer with plates (height coded coloring)

Hier sieht man die Höhendifferenzen im Bauwerk – sind über 2,5 cm. Mit den Lagenwechseln des Trägers und Platten (beim blauen). Durch die Platten wurden die Höhendifferenzen der Träger halbwegs ausgeglichen. Trotzdem musste man dies bei den Fräsungen beachten

Change in the bearing thickness on the top beam belt

Rail force bearer with plates (height coded coloring)

Hier sieht man die Höhendifferenzen im Bauwerk – sind über 2,5 cm. Mit den Lagenwechseln des Trägers und Platten (beim blauen). Durch die Platten wurden die Höhendifferenzen der Träger halbwegs ausgeglichen. Trotzdem musste man dies bei den Fräsungen beachten

Bearing plate not detectable by classical surveying

Rail force bearer with plates (height coded coloring)

Hier sieht man die Höhendifferenzen im Bauwerk – sind über 2,5 cm. Mit den Lagenwechseln des Trägers und Platten (beim blauen). Durch die Platten wurden die Höhendifferenzen der Träger halbwegs ausgeglichen. Trotzdem musste man dies bei den Fräsungen beachten

Rail force bearer with plates (height coded coloring)

The height differences in the structure are shown ~ 2,5 cm. It‘s still the main point of focus during the menufacturing of the sleepers

Results of the beam measurement homogenity checkGegengleis-Träger mit Plattungen (Höhencodierte Einfärbung)

Gegengleis-Träger mit Plattungen (Höhencodierte Einfärbung)

SiRailScan processing Results

•Detection of the sleeper coordinates in pointfiles

• Half automated determination of the beams heights for the sleepers

•Summary Output of the data in Excel

• Transfer of the result heights and coordinates to Ver.esm

Gegengleis-Träger mit Plattungen (Höhencodierte Einfärbung)

2.4 Generate the sleepers register with Verm.esn Import the coordinates and heights to Verm.esn

Setting of the beam widths for calculation of possible not measured points

Setting of the designed track geometry (chainage, track, gradient)!

Automatic calculation of the sleeper file with the beam heights

Automatic calculation of the sleeper files -BRS (optional also in Excel) for the sleeper manufacturer

2.4 Generate the sleepers register with Verm.esn

3 Impressions of the building structure

Bridge over the Weser – frame bridge

…Extracting old sleepers

Build in the new sleepers…

Put the new rails on and lock them

...Align the sleepers, marking and drilling, then screwing

...Put on the frame based protectors (yelow)

4 Summary / Conclusion• The demanded precision for the sleeper modernization (3mm in xy, 2mm

in z) were fulfilled with the multi sensor scanning system and the optimized processing. Brand new and innovative method!

• The advantage is the short locking time of the track for the measurement• Half automated algorithms for detecting the beams heights and edges• detection of the beam shapes (heights and edges) in one run via 3D

technique• Continues (complete) model of the beam – not just spots • Complete documentation of every sleeper, beam and the near

environment relations in 3D - preservation of evidence