Main Menu

See All Acoustic End-of-Line Test Systems See All DAQ and instruments See All Electroacoustics See All Software See All Transducers See All Vibration Testing Equipment See All Academy See All Resource Center See All Applications See All Industries See All Insights See All Services See All Support See All Our Business See All Our History See All Our Sustainability Commitment See All Global Presence

Main Menu

See All Actuators See All Combustion Engines See All Durability See All eDrive See All Production Testing Sensors See All Transmission & Gearboxes See All Turbo Charger See All Industrial electronics See All S&V Signal conditioner See All DAQ Systems See All Power Analyser See All S&V Hand-held devices See All High Precision and Calibration Systems See All Test Solutions See All nCode - Durability and Fatigue Analysis See All ReliaSoft - Reliability Analysis and Management See All Test Data Management See All DAQ Software See All Drivers & API See All Utility See All Vibration Control See All Acoustic See All Current / voltage See All Displacement See All Load Cells See All Pressure See All Strain Gauges See All Vibration See All Torque See All LDS Shaker Systems See All Vibration Controllers See All Power Amplifiers See All Accessories for Vibration Testing Equipment See All Training Courses See All Acoustics See All Asset & Process Monitoring See All Custom Sensors See All Data Acquisition & Analysis See All Durability & Fatigue See All Electric Power Testing See All NVH See All Reliability See All Smart Sensors See All Vibration See All Weighing See All Automotive & Ground Transportation See All Calibration See All Installation, Maintenance & Repair See All Support Brüel & Kjær See All Release Notes See All Compliance See All Our People

Main Menu

See All QuantumX See All LAN-XI See All SomatXR See All MGCplus See All CANHEAD See All Optical Interrogators See All GenHS See All API See All Microphone Cartridges See All Microphone Sets See All Microphone Pre-amplifiers See All Sound Sources See All Acoustic Calibrators See All Special Microphones See All Accessories for acoustic transducers See All Experimental testing See All Transducer Manufacturing (OEM) See All CCLD (IEPE) accelerometers See All Charge Accelerometers See All Rotating See All Non-rotating (calibration) See All Electroacoustics See All Noise Source Identification See All Environmental Noise See All Sound Power and Sound Pressure See All Noise Certification See All Industrial Process Control See All Structural Health Monitoring See All Electrical Devices Testing See All Electrical Systems Testing See All Grid Testing See All High-Voltage Testing See All Vibration Testing with Electrodynamic Shakers See All Structural Dynamics See All Machine Analysis and Diagnostics See All Dynamic Weighing See All Calibration Services for Transducers See All Calibration Services for Handheld Instruments See All Calibration Services for Instruments & DAQ See All On-Site Calibration See All Resources See All Software License Management

Holmenbrua: Analyzing the carrying capacity

Holmenbrua, Norway


The carrying capacity of the Holmenbrua bridge in Norway is weakened


The load that today’s traffic inflicts on Holmenbrua in Drammen is much higher than what was originally predicted when the bridge was built in the early 1960’s.

Due to a significant increase in traffic volume, examinations of the bridge’s construction was initiated to determine if it could withstand the burden it was exposed to or whether improvements were needed.

To analyze the impact the increased traffic volume had on Holmenbrua’s construction, HBK was assigned by Rambøll Norge to conduct the necessary measurements on a given area of the underside of the bridge using strain gauges.

The strain gauges were attached to five longitudinal steel rods, or rebars, to log tension and compression in the material by the passing of a truck weighing 50 ton. For full exposure of the rebars and to get the best utilization of the strain gauges possible, a part of the concrete around the rebars was removed.

“It was essential that the surface of material where we attached the strain gauges was treated” says Herman Lingefelt, project engineer at HBK.

“We do this to make sure the strain gauges provide the correct measurements. Even wrong coarseness on the surface can result in the glue not transmitting the strain of steel correctly.In this case, we had to grind away the rust and then brush with sandpaper. It may seem  simple, but it requires a lot of practical know-how.”

The strain gauges were adjusted to the environment in which they were to operate in, taking into consideration temperature variations in the area. This was so that they would follow the natural expansion and compression in the material caused by temperature.

Because Holmenbrua is located in a moist environment, HBK also used a coating over the measuring points to prevent the gauges from losing their grip due to rust or short circuits in the steel.

The results of the measurements were consistent with the deflection the bridge experienced and, based on the measurements made by HBK, Rambøll concluded that the bridge’s capacity was so weakened, that reduced weight limits were recommended. 

“Measurements like these are very important to uncover security implications that increased load may have on the material in a construction, and shows how important it is to use reliable measurement techniques. Exact knowledge of the bridge's condition is essential for municipal and transport managers,” says Bjarne Hauge of HBK Norway.

Rambøll is satisfied with HBK’s cooperation: ”Using one supplier to conduct the measurements was efficient and saved us time. The work HBK did on Holmenbrua was conducted in a precise and accurate way, and we are very pleased with our cooperation”, says Jon Halden at Rambøll Norge.


Ramboll is a global architecture, engineering, and consultancy company, delivering expertise and sustainable solutions to clients and partners.

Founded in Denmark in 1945, Ramboll today operates across 35 countries. We combine deep local insight and experience with a global knowledge base to create sustainable societies and drive positive change for our clients. We call it: Bright Ideas. Sustainable change.

As The Partner for Sustainable Change, we enable our stakeholders to realise their goals and navigate the transition to a more sustainable future.

Jon Halden Rambøll Norge

Technology used

Other case studies