The Road Less Travelled: Innovative Digitisation of a Mountain Road with the Leica Pegasus:Two Ultimate

移动映射解决方案业务经理Raphael Goudard

The alpine roads in Berchtesgadener Land, Germany, offer some of the most breathtaking views in the world. As the gateway to tourist areas in the southeastern tip of Bavaria, it’s vital to the local economy that the roads are kept in a good condition. The responsibility for that falls to The Traunstein State Building Authority (TSBA). TSBA manages the alpine roads in addition to a network that includes hundreds of kilometres of federal and state roads, walking and cycling paths, bridges, support structures and tunnels. A pioneer in using digital methods, TSBA wanted to create a digital record of the area as a basis for planned construction work. The Authority askedgeovision, surveying and geospatial data management experts, to survey a 3.2 km stretch. After exploring options,geovisionused a Leica Geosystems mobile mapping solution to digitally capture the road and its retaining walls. The project was the first time that mobile mapping had been applied to this type of challenge.

Challenging physical constraints for data capture

With a 23% slope in some places and huge drops into the valley below, the roads in Berchtesgadener Land are not easy to survey. It’s particularly difficult to access both sides of the retaining walls, as they are built on steep, heavily overgrown terrain. Due to the altitude and remoteness there was a weak GNSS signal over almost the entire distance, especially in the five tunnels included in the survey area. On top of the physical constraints, the survey also needed to be carried out quickly. The road could not be closed or blocked for long, to keep the route free for tourist buses. Nevertheless, because the data obtained from the survey was to be used as the basis for planned construction work, the road and walls needed to be recorded with the greatest possible accuracy.

Mobile mapping met all the project evaluation criteria

The IngGeovisionteam are highly experienced in holistic surveying. They have been the digitisation partner for buildings, plants and other infrastructure in more than 1,000 successful laser scanning projects. For the Berchtesgadener Land project, they considered various methods: laser scanning via a drone, tachymeter measurement, a static scan and mobile mapping. The evaluation criteria included time spent on site, accuracy of the data, ability to detect the retaining walls and the road condition in high resolution. Finally, whether the method could be used to gather photo documentation and point cloud data in one operation.

A drone was ruled out because it could only deliver photos, tachymeter surveying because it couldn’t deliver photos or point cloud data. A static scan would take too long and couldn’t be positioned on the outside of the walls in many places. Although untested in this scenario, mobile mapping was able to deliver on every criteria. Mobile mapping systems combine sophisticated hardware sensors and software technologies to take laser scanning off the static tripod, letting the team capture accurate 3D data by car.

Unconventional attachment of the scanner solved the site access problem

ingGeovision使用Leica Pegasus Ultimate II移动映射平台制定扫描解决方案。巧妙的是，为了捕获挡土墙的两面，Leica Pegasus Ultimate II不仅安装在汽车的屋顶上，而且还安装在挖掘机的桶上。这使扫描仪可以悬挂在墙壁的边缘并捕获外部，没有人为安全的风险。控制点的测量是通过转速计TS16进行的，并使用静态RTC 360扫描隧道，以寻找历史排水系统。使用Leica Pegasus Manager，Leica Cyclone和Leica Cyclone 3DR评估了数据。

Delivering fast and flexible scanning

A major benefit of using the mobile mapping solution was the short amount of time on site. It took only half a day for the Leica Pegasus Ultimate II to record the 3.2km of road by car and a further half day to record the difficult sections of retaining wall, when mounted to an excavator. Even during this time, tourist vehicles were still able to use the road, meaning that the inspection had minimum impact on the local economy. Approximately 162 GB of raw data was collected, which resulted in 600 GB of processed data - ultimately delivering the digital terrain model and inventory plans necessary to inform future building work. Meeting TSBA’s requirement for accuracy, the data had an absolute accuracy to within 2 - 3cm.

The evolution of mobile mapping: multiple uses

自2019年以来，TSBA一直是BIM的试点建筑办公室。当局设法将高度的数字化为其管理层的资产提供了高度的数字化，从而使计划，建设和维护更加有效。通过这个项目，在定期建造检查期间，第一次实现了高山路的完全数字化。愿意geovisionand TSBA to innovate with mobile mapping for this purpose has created a new proven method of reality capture for difficult and high altitude terrain. It’s certain to be used again.

"Mobile Mapping is so advanced nowadays, it can be used also for Monitoring purpose. Within the evaluation of possible data capture solutions the Leica Pegasus:Two Ultimate was the fastest and most accurate solution for the detection of the area.”Sven Gollub，Ing Geovision项目经理。