Protecting human lives and valuable cultural assets with Leica Geosystems technology

In September 2021, a fire destroyed the oldest house on Karolinenstraße in downtown Augsburg. With the help of a scanning total station from Leica Geosystems, the German Federal Agency for Technical Relief (THW) succeeded in protecting emergency response services and rescuing a historically significant artefact. The 3D scan of the facade now aids reconstruction.

On Friday, 10 September 2021, at around 5:20 p.m., several emergency calls are received by the operations centre in Augsburg, Bavaria. The callers report a residential fire on the historic Karolinenstraße. Due to the volume of emergency calls, the incident command service quickly mobilizes a second firefighting unit. Upon the arrival of the first response team, dense black smoke is already billowing from the first attic floor at the front of the house.

As it turns out later, this is where the fire broke out. At this point, it's unclear whether there are still people in the upper part of the house. Two crews immediately enter the first attic floor via the staircase for rescue operations and firefighting. At the same time, the fire is being extinguished from the outside via the turntable ladder. 

Complex firefighting efforts of a dynamic fire

After about half an hour, the fire seems to be extinguished. All persons in the house managed to reach safety in time. However, the roof truss and walls continue to radiate immense heat, and the fire shows increased dynamics.

Due to wall cavities and the building's substance, hard-to-control ventilation paths and "fire bridges" are established. Suddenly, the basement is also ablaze. "Even though the fire brigade extinguished with heavy foam, it's tough to get such a fire under control," explains Kevin Kärcher, a voluntary technical advisor at the German Federal Agency for Technical Relief in Weingarten. He was involved in this fire and witnessed how much the emergency services were challenged. "The firefighting efforts were very complex and could not be accomplished with standard procedures because, due to the construction, there was hardly any access to the embers. At such a fire 300 years ago, half the city would have been destroyed," Kärcher is convinced. Around 10:30 p.m., the internal attack is discontinued to protect the firefighters. Due to the duration and intensity of the fire, the building is becoming increasingly unstable.

Decision: Demolition of the Building

On Saturday morning, experts begin the demolition of the house to bring the fire completely under control. To facilitate the demolition, a 70-tonne track excavator is organised.

To prevent this heavyweight from damaging the road surface, a 50 cm high layer of gravel is applied. In the meantime, the German Federal Agency for Technical Relief (THW) team in Weingarten installs a laser-supported incident site security system (ESS).

For this, THW works hand in hand with the Augsburg professional fire brigade. "The stability of the building had to be constantly checked from the time of arrival until the building was demolished. Therefore, we set up the measuring station so that the front of the building and the roof truss sides in the rear of the building area were visible," says Kevin Kärcher.

The measuring prisms are attached to the building by firefighters wearing breathing apparatus using a fire brigade ladder. "We literally glued the reference points M1 and M2 to the front of the building using cyanoacrylate and activator and fixed M3 and M4 to the roof truss with two screws each. We glued the calibration point to the adjacent building with PU90 (polyurethane adhesive) to check the stability of the measuring station itself." This creates a reference system with three prisms at a 90° angle to the Leica MultiStation.

Assessing Hazards Correctly with the Help of Technology

THW continuously analyses the building structure, conducting a referencing in two positions every 15 minutes to monitor the vertical and horizontal displacements of the building. If there had been an uncontrolled movement of parts of the building and an acute risk of collapse, THW would have been able to issue a warning immediately. This is also the main task of THW; as Kevin Kärcher explains, "The ESS and our work primarily serve to protect the emergency crews. They entrust us with their lives. This requires the utmost professionalism, reliability, and implementation strength in the team and equipment." In Augsburg, the Leica Nova MS50 MultiStation was used.

"To be able to assess dangerous situations correctly, we must be able to collect as much information as possible in as short a time as possible and be able to measure and capture complex structures.
The MultiStation allows us to do this, combining a total station and a laser scanner in one platform."

Kevin Kärcher initially carried out a single-layer measurement to generate a faster measurement cycle. Due to the heavy smoke development, he switches to a double-layer measurement during the operation. This reduced the measurement noise. The measurement points M3 and M4 are permanently measured at the end of the measurement sequence in one layer to obtain a higher measurement frequency again. The MultiStation defied external influences, as Kevin Kärcher confirms: "The measurement data and the measuring equipment provided clear data - despite smoke development and dust during the demolition of the building by a specialist company." The measurement showed no significant movement during the observation period before demolishing the building.

Enabling rescue and work amidst the ruins

During the fire in Augsburg, the ESS fulfilled several tasks, explains Kevin Kärcher. "First and foremost, as mentioned, it was about protecting the emergency personnel. Therefore, we monitored the building's movements to enable work in the shadow of the debris on Karolinenstraße. This was necessary to carry out the ongoing extinguishing work in inaccessible areas. It was about saving what could be saved."

This also applied to a special artefact. The "Karolinenstraße 15" was the oldest house on the street and only one of two buildings that had survived the Augsburg bombing night from 25 February to 26, 1944. Parts of the listed building date back to the mid-16th century. The curved gable dormer with the valuable baroque house Madonna from the 18th century was particularly striking. "In a unique action, stonemasons and firefighters secured and brought down the historically significant Madonna figure. That was a special moment in the surveillance phase," recalls Kevin Kärcher.

3D visualisation aids in reconstruction

The demolition work lasts almost 24 hours. Over the following three days, post-fire inspections are carried out. However, a new outbreak of fire occurs on 14 September. As a result, more than 100 cubic meters of fire load are excavated, and two cavities, previously out of reach, are opened. The fire was eventually extinguished after five days. The property damage amounted to several million euros. The historically significant house is being rebuilt, and the original façade will be restored. Even during the firefighting efforts, the Lower Monument Protection Authority of the city of Augsburg was on site to photograph the building. Kevin Kärcher recalls the encounter, "They told us they wanted to rebuild and preserve the façade. The photos would help them with that. We then offered to scan the façade in a five-millimetre grid. The monument protection authority gratefully accepted this offer."

Viewing Point Cloud Data On-site

With the Leica Nova MS50 MultiStation, THW captured the listed facade with multiple scans and recorded it as a highly accurate 3D point cloud.

For the area of the gable dormer, a finer resolution was chosen to secure the contours for the monument office. "An important side effect that we appreciate so much about Leica's scanning total station is the ability to view the scanned point cloud data on site with the Leica Captivate software," adds THW consultant Kevin Kärcher, who has already measured around two and a half thousand hours himself. "The user-friendly field software provides easily understandable data in 2D and 3D for any type of surveying project." In the case of Augsburg, a detailed virtual image of the façade was created, which is now providing valuable support for the reconstruction.

The cause of the fire was a defect while charging a private e-scooter battery. Small cause, big damage.

Conclusion:
The fire of the historically important building in Augsburg has clearly demonstrated THW's invaluable support in emergency situations and how indispensable the MS50 Scanning Total Station from Leica Geosystems has become in operations where public safety is at risk. The technology aids in saving lives, protecting emergency personnel, and preserving valuable cultural assets.

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About the person Kevin Kärcher

Since 1998, Kevin Kärcher has been serving as a volunteer technical advisor at the Weingarten branch of the German Federal Agency for Technical Relief (THW) in Baden-Württemberg. In his professional capacity, he works at Schuler Pressen GmbH, the largest press and forming manufacturer globally, boasting over 5,000 employees. As the Head of Engineering at Schuler Pressen, Kärcher oversees the Mechanical, Electrical, and Real-Time departments. Concurrently, he serves as a lecturer at Ravensburg-Weingarten University of Applied Sciences, specializing in forming technology and forming machines. The 45-year-old Kärcher resides near Weingarten with his family.

About the THW

Author:Manuel Huber
www.huberkom.ch

Editor: Malgorzata Krol
Global Director Marketing Communications - Public Safety & Forensics
Hexagon Geosystems