Gyroscope measuring system GYROMAT: High-precision surveys for cost-effective planning reliability

(Story and interviews)

Developed for extreme conditions underground, used in extreme tunnel construction: DMT’s gyromat has already set the direction for around 4,000 projects. Other industries are now discovering the world’s most accurate surveying gyroscope.

If you ask Dr. Jörg Niese how exactly the gyromat measures, he will generally answer by citing an example: “If you were to cut a cake into 400 pieces and then cut one of these little pieces of cake into 1,000 even smaller pieces, then you would have an idea of the accuracy involved.” In technical jargon, this means that the gyromat measures with a directional measurement accuracy of 0.8/1,000 Gon, which corresponds to an arc deviation of about 1.2 centimetres over a distance of one kilometre. Its accuracy makes the current model, known as GYROMAT 5000, the gold standard of survey gyroscopes.

This ergonomic and compact device has a gyroscope at its heart which is suspended from a sensitive torsion strap and observed by a very accurate electro-optical sensor. Gravity and the Earth’s rotation ensure that the axis of rotation of the gyroscope wants to align parallel to the Earth’s axis, which points to the North Pole. Using the gyromat and another device, a tachymeter, it is possible to determine the exact angle between a measured line and geographical north. “And the beauty of it is that I can do it anywhere: in a tunnel, a ship’s hull or an industrial hall,” explains Niese, who, as a product manager at DMT, is in charge of the gyromat.

The gyromat is used where no GPS signal can reach and where the highest directional accuracy is required, because any deviation can lead to costs to the tune of millions of euros. This is the case with the construction of kilometre-long tunnels and of large ships, and increasingly in the aerospace industry and other industrial sectors. “In longer tunnel projects, two or more huge tunnel boring machines are often used,” says Niese. They start drilling at different points and, of course, have to meet at the end with the smallest possible deviation. As a service provider, DMT has previously provided metrological support for the Eurotunnel under the English Channel and the longest road tunnel in the Alps (the Gotthardt Tunnel). “These were flagship projects which earned us a good reputation worldwide,” says Volker Schultheiß, project manager of the surveying team at DMT. So it is not surprising that the company is also working on the Brenner Base Tunnel, which, after completion, will be the longest railway tunnel in the world at a length of 64 kilometres (including all access tunnels).

DMT’s expertise and the surveying gyroscope were also used for the underground tunnels to the World Cup stadiums in Qatar, where Volker Schultheiß and his team were responsible for simultaneously managing 16 tunnel boring machines. During their assignments, the surveyors sometimes encounter extreme conditions, including temperatures of up to 45 degrees in a tunnel, for example. “The humidity is really extreme, and it sometimes knocks you out,” says Schultheiß, who travels a lot in the Middle East. Smaller diameters of three metres in power line tunnels in Berlin or supply tunnels for the EXPO in Dubai with a diameter of over ten metres are just as much a part of the repertoire as the large road and railway tunnels with diameters of around 15 metres.

The gyromat is also the directional measure of all things in the construction of underground railways in Scandinavian cities such as Gothenburg and Stockholm, where the tunnels are blasted through hard rock. “We act as a kind of insurance provider for our customers,” says Schultheiß. In many cases, the gyromat measurements confirm the customer’s data, thereby offering them certainty. But Volker Schultheiß is also familiar with other cases: “With the gyromat we once discovered that a tunnel had deviated several metres off its axis.” Thanks to DMT, the customer was able to correct this.

“The accuracy of the gyromat is its unique selling point,” says Jens Schweitzer, Director of Machine Diagnostics & Geomeasuring Systems at DMT. “It’s a very durable high-end system that we’re constantly developing.” The gyromat is also available to buy and already worldwide in use. With each new version, the device has become more precise, faster and safer in recent years.

In the meantime, other industries have discovered this phenomenal accuracy for themselves. “In shipbuilding, you need measurements to align the machine parts,” reports Niese, who, as a product manager, trains and supervises customers in the operation of the device. Many large shipyards use the gyromat to calibrate their own calibration system. The navigation equipment of the ships they build is calibrated on turntables. DMT’s surveying gyroscope can be used to determine exactly when the table is aligned with geographical north. And aerospace technology companies are also using the gyromat as a reference standard to calibrate their own gyrocompass systems, which are used in aeroplanes, helicopters and satellites, for example. Thus it is that the gyromat, developed in 1978 for underground use, continues to offer orientation on land, at sea and in the air to customers all over the world in 2023.