Norwegian Public Roads Administration Research Articles

Asset management, condition monitoring and Digital Twins: damage detection and virtual inspection on a reinforced concrete bridge

In April 2021 Stavå bridge, a main bridge on E6 in Norway, was abruptly closed for traffic. A structural defect had seriously compromised the bridge’s structural integrity. The Norwegian Public Roads Administration (NPRA) closed it, made a temporary solution and reopened with severe traffic restrictions. The incident was alerted through what constitutes the bridge’s Digital Twin processing data from Internet of Things sensors. The solution was crucial in online and offline diagnostics, the case demonstrating the value of technologies to tackle emerging dangerous situations as well as acting preventively. A critical and rapidly developing damage was detected in time to stop the development, but not in time to avoid the incident altogether. The paper puts risk in a broader perspective for an organization responsible for highway infrastructure. It positions online monitoring and Digital Twins in the context of Risk- and Condition-Based Maintenance. The situation that arose at Stavå bridge, and how it was detected, analysed, and diagnosed during virtual inspection, is described. The case demonstrates how combining physics-based methods with Machine Learning can facilitate damage detection and diagnostics. A summary of lessons learnt, both from technical and organisational perspectives, as well as plans of future work, is presented.

Behavior of a Rock Mass in Uplift Field Tests of Rock Anchors

AbstractRock anchors are high-capacity reinforcement measures used to stabilize large-scale infrastructures. According to the literature, they can fail in one of the four ways: (1) steel tensile failure; (2) tendon–grout interface failure; (3) grout–rock interface failure; and (4) rock mass uplift failure. Rock mass uplift field tests were performed in a limestone quarry to test this fourth failure mode. The tests were designed to induce rock mass failure around rock anchors. The ground surface heaved asymmetrically around the anchors and the pre-existing joints in the rock mass tended to open first. The seismic activity in the rock mass was greatest close to the anchor, decreasing with distance. The failure crater in the rock followed the joint sets in the rock mass, and the shape was partly controlled by the pre-existing joints. The apex angle of the failures was measured to be between 125 and 140$$^{\circ }$$ ∘ . The horizontal stress in the rock mass increased when the anchor was pulled, indicating load arching around the anchor. The observed failure was a combination of rock mass uplift and grout–rock bond failure. The measured anchor capacity was much higher than the estimated rock mass capacity using the recommended design methods of the Norwegian Public Roads Administration.

An image processing approach to reconstruct wind using long-range wind lidars

Lidar-based wind sensing technology, originally used in the wind energy sector, is now being utilized in wind engineering to monitor wind action for designing fjord-crossing infrastructure like long-span bridges. Accurate estimation of design wind loads is crucial for the design process of such bridges. This paper examines wind data from two pairs of long-range lidars positioned along one side of the Sulafjorden, Norway, in a measurement campaign initiated by the Norwegian Public Roads Administration (NPRA). Two different scanning modes, the Plan Position Indicator (PPI) mode and the staring mode, with the fixed line-of-sight (LOS) orientation, are used to determine the line-of-sight wind speeds, the wind direction, and the related along wind speed. An image processing approach is used to compute along wind velocity information from all range gates based on the LOS wind speeds from two near-parallel lidar beams. The estimated along wind velocity is validated through wind data calculated at the intersection point of the two lidars, which provides velocity data with two horizontal components. The image-based reconstruction is found to produce reasonable wind speed estimates with a goodness-of-fit coefficient of R2 = 0.903. The mean wind direction estimate is smoothened but still comparable to the actual wind direction. The image processing approach shows promising potential to provide wind speed and direction information for all range gates for the lidar setup used, which can supplement traditional single-point wind velocity characterization by dual lidars.

Experience and status of instrumented durability monitoring of concrete bridges in Norway

AbstractWithin the Norwegian Public Roads Administration, the use sensors of durability monitoring (potentials, corrosion rates, resistivity etc.) was first investigated during a research project on a North Norwegian bridge in the beginning of the 1990s. The knowledge earned from this initial test has been used to compile national recommendations shortly after. Still, durability sensors are seldom used on bridges in Norway today, apart from systems for cathodic protection where potential measurements are frequently executed. During the 1990s to 2020s, durability monitoring was several times applied in research projects and results show how sensors effectively can be used to assess corrosion and durability in concrete elements. To promote the use of durability sensors, the Norwegian Concrete Repair Association newly published a guideline on how to use, install and analyze durability monitoring systems.The paper summarized experience with the use of sensors for durability monitoring on Norwegian bridges and research projects. Today, there is an increasing demand for solutions allowing the automated monitoring for bridge safety and durability. The status and possible further applications of durability sensors on Norwegian bridges are briefly discussed at the end of the paper.

Development of extreme fjord crossings in the E39 coastal highway route project, Norway – a review

An overview of the development of fjord-crossing bridge technologies under the Norwegian coastal highway route E39 project is provided in this particle. Due to the extensive development and research scope, only a brief introduction to the concepts’ development is presented. This includes the different novel marine bridges developed by the Norwegian Public Roads Administration in recent years, in addition to analysis and model test activities accompanying the design process.

CFD-modelling of large-scale LH2 release and explosion experiments

As a part of zero emission ambitions within the maritime, aviation and elsewhere, liquid hydrogen (LH2) will increasingly be used as an energy carrier and fuel in the coming years. It is therefore important to understand safety aspects of LH2, including gas dispersion and explosion properties. In the process of building the world’s first ferry using LH2 as fuel the Norwegian Public Roads Administration commissioned large-scale LH2 release tests to study dispersion and explosion properties relevant for the design and approval processes. Experiments with LH2 releases both indoor and outdoor were performed. In this article these experiments are described and compared to simulations with the CFD-model FLACS. The aim of the modelling is both to better understand the experiments performed, and to demonstrate that important phenomena and physics related to LH2 safety assessments for approval processes can be simulated and predicted with confidence.

Geohazard Monitoring by UAV: The Future Technology for Remote Decision Support

In Norway, as in many other parts of the world, roadside geohazards pose a serious and frequent threat to the transportation network and to road users. Roadway closures due to avalanches, landslides, and rockfalls incur high economic costs and greatly impact the reliability of critical transportation networks. To meet these challenges, road owners and operators, like the Norwegian Public Roads Administration, are adopting autonomous Uncrewed Aerial Vehicles, known as UAVs, to monitor and evaluate geohazards and to support decision-making.

Prevalence of alcohol and drugs among drivers killed in road traffic crashes in Norway during 2011–2020

Objective Driving under the influence of alcohol or drugs is one of the main contributing causes of serious road traffic crashes (RTCs). This study aimed to investigate the involvement of alcohol and drugs in driver fatalities in Norway during 2011–2020 and compare the findings with data from the previous decade. Methods We linked the results of forensic toxicology testing for alcohol and the 17 most commonly used drugs assigned with legal limits with data on fatal road traffic crashes obtained from Statistics Norway and the Norwegian Public Roads Administration. Results The number of fatalities had decreased significantly since the previous decade, while the proportion of drivers and riders tested for alcohol and drug use increased. Blood alcohol concentrations at the legal limit or higher were found in 14.4% and psychoactive drugs were detected in 15.8% of the cases; 10.7% tested positive for illicit drugs, and 10.1% for medicinal drugs. The most prevalent illicit drugs were tetrahydrocannabinol (7.9%) and amphetamine/methamphetamine (4.7%), whereas the most prevalent medicinal drugs were clonazepam (3.7%) and diazepam (2.2%). Conclusions There was a marked reduction in the number of motor vehicle drivers killed in RTCs compared with the previous decade, and also a reduction in the prevalence of alcohol. For other substances, there were no marked changes in the prevalence.

Environmental noise and densification of cities - a paradox?

Densification of cities is used because of numerous benefits and fits well with sustainable development. Densification can however lead to disadvantages, especially related to environmental noise. In this paper, we ask: is it possible to restrict disadvantages by balancing out these with benefits? Access to quiet areas in cities plays an important part here, due to benefits related to well-being and health for inhabitants. We will give an overview of Norwegian guidelines on environmental noise and how these are implemented. We look at the situation from the Norwegian Public Roads Administration's viewpoint and include the experiences from a consultant company. We present projects situated in Norway, a large country with a relatively low population density compared to most other European countries. However, access to quiet areas isn't optimal in the largest cities, which leads to problems related to environmental noise and densification. Our experience is that it's crucial to include noise assessment in the early stages of planning. Together we need to find a balance, where new roads and new dwelling areas can be realised without more negative than positive aspects. The final goal must be, that there is no paradox!

Response validation of a submerged floating tunnel segment

Tube segments are the main structural components of submerged floating tunnels (SFTs). Accurately estimating the hydrodynamic properties of these components is of critical importance for the optimization and safe design of SFTs. Therefore, it is essential to understand the uncertainty associated with the frequently used assumptions inherent in the state-of-the-art calculation models for SFTs. In this paper, experimental data provided by the Norwegian Public Roads Administration (NPRA) were used to validate the hydrodynamic responses of a truncated tube segment of a SFT. The excitation force and motion response of the tube segment under different loading and constraint conditions were verified. The effects of different wave headings, submerged depths, and restoring spring stiffnesses on the hydrodynamic features of the SFT's tube segment were further investigated. The numerical results generally coincide well with the experimental results. Some interesting properties of the tube segment are presented, and the uncertainty level related to the state-of-the-art models is made clear. These are for instance regarding the main tube as a Morison element and neglecting the slow-drift force effects. The aspects that need to be given more attention to achieve more trustworthy estimations of the hydrodynamic responses are summarized. The results presented should be of value in relation to verification of analysis methods for SFTs, which represents an important step towards enhancing trustworthy design models.

Early contractor involvement in the Valdres Project Delivery Model

For years the need for road maintenance has been rising in Norway, and the Norwegian Public Road Administration (NPRA) has tried to find a solution. The Valdres model is a project delivery model developed by the NPRA for use in road refurbishment projects to utilize resources more effectively. By using early contractor involvement (ECI), the NPRA combines their own expertise with the contractors’ buildability knowledge in the design phase to reduce risk and uncertainty with smarter and cost-reducing solutions. The studied pilot project E16 Fagernes-Øylo is chosen as case for testing the Valdres model. Ten semi-structured interviews with key informants have been carried out together with a document study to fill the knowledge gap regarding the Valdres model. The contractor was procured by a competitive dialogue (CD) before the final zoning plan was settled and has positively impacted on buildability and trust in the design phase. ECI was combined with Target Value Design (TVD) and Integrated Concurrent Engineering (ICE) to integrate lean thinking and enhance value creation in the design phase. This seemed to give fewer conflicts and cost reductions through a streamlined planning process. The studied case has experienced less changes and higher levels of cooperation with working towards the same goal in the construction phase compared to traditional project delivery models. Overall, the Valdres model has so far been a success.

Numerical simulation of wave-induced hydroelastic response and flow-induced vibration of a twin-tube submerged floating tunnel

The Norwegian Public Road Administration is planning to upgrade Coastal Highway E39 by replacing ferry connections with floating bridges or submerged floating tunnels (SFTs). This study considers a potential pontoon-supported curved SFT designed for crossing Sognefjorden at a submergence of 12 m. It consists of two identical tubes with a diameter of 12.6 m each in a tandem configuration and with a length of approximately 4 km. The natural frequencies of the low-order modes are well within the energy content in the spectra of the second-order difference-frequency wave excitation forces and the vortex shedding-induced forces. In this paper, numerical simulation of wave-induced hydroelastic response and flow-induced vibrations of the twin-tube SFT is performed. Long- and short-crested waves, the first and second order wave loads, are considered. A time-domain approach to simulate crossflow vortex-induced vibration (VIV) and VIV-amplified inline drag forces, partly based on the coefficients obtained experimentally, is established and applied. The focus is on extreme conditions – relating to ultimate strength limit states. The second-order wave load substantially affects the lateral motion and lateral bending moment, as expected. The short-crested waves influence the response in both the lateral and vertical directions by exciting asymmetric eigenmodes. In strong flow conditions, once VIV is excited, the standard deviation of the vertical motion (of about 30% of the diameter) and the bending moment about the horizontal axis is more that an order of magnitude larger than that induced by the wave loads. The simulation of the wave- and flow-induced load effects provides a good reference for the design of SFTs.

Encountering the machinery of bureaucracy - enacting cultural heritage as facts, maps, and mathematics in environmental impact assessments

ABSTRACT Research into Heritage Impact Assessment (HIA) has criticised the process of Environmental Impact Assessment (EIA) as a tool for protecting cultural heritage, claiming that assessments of impacts on cultural heritage become marginalised and fail to inform key decisions during EIA processes. Many suggestions have been made for optimising the process and providing a platform to improve the understanding of cultural heritage. This article aims to enrich this discussion by challenging established ideas about what constitutes an ‘actor’ in a planning context, arguing that there is a need to expand this term to encompass the bureaucratic production of knowledge and thus to analyse the impact of the production and shape of knowledge on the alleged marginalisation of cultural heritage. This article examines the relevant knowledge production process and the limitations of current practices and in doing so highlights how the knowledge production aspect of an EIA process seems to stabilise cultural heritage as a fact, making it equivalent and comparable to other environmental subjects. A central finding is that this similarity in some cases causes cultural heritage to become invisible in an EIA process, causing it to slip through the net in final decision-making. The empirical starting point for this article is the Norwegian Public Roads Administration (NPRA/Statens Vegvesen) and its in-house EIA manual, the Handbook on Impact Analyses (Handbook V712), while the theoretical resources are derived mainly from Science and Technology Studies (STS) and Actor-Network Theory (ANT).

What predicts the number of attempts to pass the driving test? A case from Norwegian driving education model

This study focuses on examining the relationships between the variables within the driving education process in Norway by aiming to answer three research questions: 1) Is there a difference between learner drivers above and below 25 years old in time spent at different steps and between theory and practical tests? 2) Do the time spent during different steps of the driving education, the number of attempts in the theory and practical tests differ by demographic variables? 3) What variables predict the number of attempts to pass the practical test? Data were extracted from two registry systems provided by the Norwegian Public Roads Administration. It included information from a randomized sample of 452 learner drivers who took their driving license in 2017. The age mean of the learner drivers when they got their license was 24.3 and most of them (54.6%) were males. Independent samples t-test results showed that compared to the learner drivers below 25 years, those above 25 years old spent significantly more time during steps 3 and 4, and had significantly more attempts to pass both theory and practical tests. In terms of the demographic variables, age was significantly and positively correlated with the time spent during the whole driving education and the number of attempts both in the theory and practical tests indicating that time spent for driving education and the number of attempts in the tests tend to increase with the increasing age. Also, the average time spent between taking the theory test and completing step 4 was significantly more among males than females. Test location had no significant influence on the number of attempts to pass the practical test. Finally, two separate regression analyses were conducted to examine the predictors of the number of attempts to pass the practical test for learner drivers both below and above 25 years old. For both groups, the strongest predictor of the number of attempts in the practical test was time spent between the theory test and the practical test, which indicates that as the time gap between the two tests increases learner drivers are more likely to fail at the practical test. Results are discussed for their implications which could be useful to improve the driving education process both in Norway and in other countries with similar driving education models.

Estimating shear wave velocity with the SCPTu and Bender element

The shear wave velocity (vs) is an important soil and rock property that can both be used in several geotechnical problems including for evaluation of dynamic properties of soils as well as in determining the maximum value of soil stiffness at small strain. This property is also seen to give good correlations with other soil parameters used in settlement and stability analyses. The Norwegian Public Roads Administration (NPRA) has recently invested in equipment to measure this fundamental soil property both in the laboratory using bender elements and out in the field using a seismic CPTu (SCPTu). NPRA has also developed internal procedures and techniques to standardize logical interpretations. To assist with this standardization procedure, NPRA has conducted soil investigations at a site in Fredrikstad municipality in the southern part of Norway. The investigations included SCPTu and extraction of high quality mini-block samples. The shear wave velocity is estimated after consolidation in the triaxial apparatus. The laboratory program was done right after the sample extraction and repeated on stored samples a couple of weeks later. Comparison of vs measured in the laboratory was then made with the field measurements with SCPTu. The work gives comparison of the field and laboratory measurements. Correct interpretation approaches are necessary for the laboratory tests as these are found to be more sensitive to small changes in experimental conditions than the SCPTu. Recommendations on how to reduce discrepancies between laboratory and field data are given.

Piecewise deterministic Markov process for condition-based maintenance models — Application to critical infrastructures with discrete-state deterioration

In recent decades, the technology and techniques for condition monitoring have experienced a rapid development. However, there is still a need for reducing unnecessary inspections and/or preventive maintenance actions and their associated cost, through optimal design of condition-based maintenance (CBM) strategies. Accordingly, mathematical modelling and optimization of CBM has become of interest for industry managers and researchers. This work explores on the application of a piecewise deterministic Markov process (PDMP) to encompass different modelling assumptions as non-negligible maintenance delays and inspection-based condition monitoring. These assumptions are relevant for many critical infrastructures in civil engineering or in oil & gas industry whose deterioration states are classified at a very high level of abstraction among a finite and small set of possible states. A formalism to model this type of problems is proposed in which the deterministic motion of the PDMP is reduced to a trivial differential equation to track the time elapsed between events. A numerical scheme for quantification, as an approximation of the Chapman–Kolmogorov equation, is presented. Later, an illustration case dealing with CBM of road bridges by the NPRA (Norwegian Public Roads Administration) is presented, guiding through the modelling and quantification approach.

Characteristics of a project that are suitable for a relational PDM

Abstract In many countries, there is increasing interest in promoting relational PDMs to avoid the adverse objectives and conflicts that have characterized the industry due to the use of traditional forms. For countries that are new to this concept, deciding on and shifting from a traditional environment to a collaborative one is not easy while the set-up cost for an extensive relational delivery model is not justified for small, less complex projects of low strategic importance. This study focusses on identifying the project characteristics which indicate the relevance of adopting relational PDM by formulating the following research question: • Under what project characteristics should a client consider applying a relational project delivery model? This study is part of a bigger research project (E39 feryfree project) in Norway, finance by Norwegian Public Road Administration (NPRA), while the authors, combined and examined the data collected in three different study connected to E39 project using qualitative content base analysis. This research concludes with the following project characteristics which show the validity of considering relational PDM as delivery model; Fairly High Level of Uncertainty and Complexity, Time Constraints, High Risk, Large Size and Need for Innovation.

Meteorological observations in tall masts for the mapping of atmospheric flow in Norwegian fjords

Abstract. Since 2014, 11 tall meteorological masts have been erected in coastal areas of mid-Norway in order to provide observational data for a detailed description of the wind conditions at several potential fjord crossing sites. The planned fjord crossings are part of the Norwegian Public Roads Administration (NPRA) Coastal Highway E39 project. The meteorological masts are 50–100 m high and located in complex terrain near the shoreline in Halsafjorden, Julsundet and Storfjorden in the Møre og Romsdal county of Norway. Observations of the three-dimensional wind vector are made at 2–4 levels of each mast with a temporal frequency of 10 Hz. The dataset is corroborated with observed profiles of temperature at two masts, as well as observations of precipitation, atmospheric pressure, relative humidity and dew point at one site. The first masts were erected in 2014, and the measurement campaign will continue until at least 2024. The current paper describes the observational setup, and observations of key atmospheric parameters are presented and put in context with observations and climatological data from a nearby reference weather station. The 10 min and 10 Hz wind data, as well as other meteorological parameters, are publicly available through the Arctic Data Centre (https://doi.org/10.21343/z9n1-qw63; Furevik et al., 2019).

Changing oil: self-driving vehicles and the Norwegian state

Expectations regarding the imminent arrival of self-driving vehicles has prompted nations to embed such vehicles in policy and explore their potential through pilot projects. The article analyses interviews and document to explore the politics of self-driving vehicles in Norway. Using sociotechnical imaginaries as a theoretical starting point, the article finds that Norwegian policy and legislation frame self-driving vehicles in rather general terms, primarily citing expected economic gains and prospects of improving the transport sector. When these policies were operationalized in the transport innovation project Borealis, the Norwegian Public Roads Administration grafted the policies onto distinctively Norwegian use-cases: self-driving vehicles and associated infrastructures were envisioned to benefit the Norwegian fishing industry, have ramifications for standardization work within the European Union, and possibly foster a Norwegian high-tech industry. The prospect of a high-tech industry links self-driving vehicles to the green shift, a collectively imagined future in which the Norwegian petroleum industry has been phased out and replaced by ‘greener’ industries. In sum, self-driving vehicles are mobilized both as a desirable transport innovation and as part of a national narrative: through innovation relating to such vehicles, Norway might be able to phase out a petroleum-reliant economy while remaining an affluent nation with high levels of social welfare.

P.243 Experimental evaluation of the atomoxetine influence on the cognitive functions in rats

The Norwegian Public Road Administration is planning to upgrade Coastal Highway E39 by replacing ferry connections with floating bridges or submerged floating tunnels (SFTs). This study considers a potential pontoon-supported curved SFT designed for crossing Sognefjorden at a submergence of 12 m. It consists of two identical tubes with a diameter of 12.6 m each in a tandem configuration and with a length of approximately 4 km. The natural frequencies of the low-order modes are well within the energy content in the spectra of the second-order difference-frequency wave excitation forces and the vortex shedding-induced forces. In this paper, numerical simulation of wave-induced hydroelastic response and flow-induced vibrations of the twin-tube SFT is performed. Long- and short-crested waves, the first and second order wave loads, are considered. A time-domain approach to simulate crossflow vortex-induced vibration (VIV) and VIV-amplified inline drag forces, partly based on the coefficients obtained experimentally, is established and applied. The focus is on extreme conditions – relating to ultimate strength limit states. The second-order wave load substantially affects the lateral motion and lateral bending moment, as expected. The short-crested waves influence the response in both the lateral and vertical directions by exciting asymmetric eigenmodes. In strong flow conditions, once VIV is excited, the standard deviation of the vertical motion (of about 30% of the diameter) and the bending moment about the horizontal axis is more that an order of magnitude larger than that induced by the wave loads. The simulation of the wave- and flow-induced load effects provides a good reference for the design of SFTs.