Extremely accurate surveying gyroscope ensures alignment of Cairo metro tunnels

DMT is undertaking the high-precision surveying of two underground tunnels in the Egyptian capital as part of the construction of the new Cairo Metro Line 4. The aim is to ensure the exact alignment of the tunnel tubes between Cairo city centre and the Grand Egyptian Museum on the west bank of the Nile.

Cairo Metro Line 4 is one of the most important infrastructure projects for the future transport development of the Cairo metropolitan region. The new line will connect heavily frequented urban areas, relieve private transport and significantly increase the efficiency of local public transport. It will also directly link the city’s urban transport network to one of the country’s most important cultural projects: the Grand Egyptian Museum.

Continuous monitoring over almost 19km

DMT, a company of the TÜV NORD GROUP, is responsible for checking the geodetic alignment of the two tunnel tubes over a distance of almost 19km. The company is using the Gyromat – one of the world’s most accurate surveying gyroscopes – for geodetic control of tunnel excavation. The system continuously provides highly accurate direction and position data, enabling continuous monitoring of the tunnel’s course underground. Deviations from the target course can thus be detected at an early stage and compensated for in the construction process.

In addition, DMT is providing support in setting up a higher-level geodetic reference network based on satellite-based GNSS measurements, precisely coordinated fixed points and geodetic polygon chains. Particular attention is paid to the combined calculation of the various measurement data. This reference system forms the basis for all further surveying work – from control measurements and axis stakeouts to coordination between above-ground planning and underground tunnelling.

Maximum breakthrough accuracy

“As the length of the tunnel increases, the demands on geodetic control rise significantly, as even the smallest measurement deviations can add up over the course of the tunnel,” explains Benedikt Wolters, senior surveying engineer at DMT. “With the help of the Gyromat, we achieve maximum breakthrough accuracy. Our aim is to monitor the tunnelling process in such a way that deviations are detected at an early stage and construction work is supported in a targeted manner.”

Supporting safety, efficiency and long-term availability

The surveying work ensures that the planned route is followed with the highest precision, even underground, and is being carried out alongside the tunnel excavation. Precise tunnel surveying forms the basis for safety, operational efficiency and long-term availability of the infrastructure.

“The expansion of high-performance transport infrastructure is a key prerequisite for meeting the growing demand for mobility in expanding metropolitan regions. With the help of our experts and our high-precision measurement technology on site, we are helping to lay the foundations for safe and permanently stable operation,” says Jens-Peter Lux, DMT managing director and head of infrastructure & raw materials at the TÜV NORD GROUP Business Unit Energy & Resources.

DMT brings knowledge from hundreds of international tunnel and metro construction projects to the project. The combination of decades of experience and a clear focus on quality, safety and accuracy using high-precision measurement technology forms the basis for reliable project implementation, with the aim of creating a modern and sustainable transport infrastructure for the rapidly growing Cairo metropolitan region.