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Norwegian Public Roads Administration

governmentOslo, Norway

Research output, citation impact, and the most-cited recent papers from Norwegian Public Roads Administration (Norway). Aggregated across the NobleBlocks index of 300M+ scholarly works.

Total works
778
Citations
17.6K
h-index
60
i10-index
361
Also known as
Norwegian Public Roads AdministrationStatens vegvesen

Top-cited papers from Norwegian Public Roads Administration

The Living Planet Index: using species population time series to track trends in biodiversity
Jonathan Loh, Rhys E. Green, Taylor H. Ricketts, John F. Lamoreux +3 more
2005· Philosophical Transactions of the Royal Society B Biological Sciences488doi:10.1098/rstb.2004.1584

The Living Planet Index was developed to measure the changing state of the world's biodiversity over time. It uses time-series data to calculate average rates of change in a large number of populations of terrestrial, freshwater and marine vertebrate species. The dataset contains about 3000 population time series for over 1100 species. Two methods of calculating the index are outlined: the chain method and a method based on linear modelling of log-transformed data. The dataset is analysed to compare the relative representation of biogeographic realms, ecoregional biomes, threat status and taxonomic groups among species contributing to the index. The two methods show very similar results: terrestrial species declined on average by 25% from 1970 to 2000. Birds and mammals are over-represented in comparison with other vertebrate classes, and temperate species are over-represented compared with tropical species, but there is little difference in representation between threatened and non-threatened species. Some of the problems arising from over-representation are reduced by the way in which the index is calculated. It may be possible to reduce this further by post-stratification and weighting, but new information would first need to be collected for data-poor classes, realms and biomes.

Relation between Concentration of Air Pollution and Cause-Specific Mortality: Four-Year Exposures to Nitrogen Dioxide and Particulate Matter Pollutants in 470 Neighborhoods in Oslo, Norway
Øyvind Næss, Per Nafstad, Geir Aamodt, Bjørgulf Claussen +1 more
2006· American Journal of Epidemiology252doi:10.1093/aje/kwk016

This study investigated the concentration-response relation between air pollution (nitrogen dioxide and particulate matter pollutants PM(10) and PM(2.5)) and cause-specific mortality. The population included all inhabitants of Oslo, Norway, aged 51-90 years on January 1, 1992 (n = 143,842) with follow-up of deaths from 1992 to 1998. An air dispersion model (AirQUIS; Norwegian Institute for Air Research (NILU), Oslo, Norway) was used to estimate levels of exposure in 1992-1995 in all 470 administrative neighborhoods. These data were linked to census, education, and death registries. A consistent effect on all causes of death was found for both sexes and age groups by all indicators of air pollution. The effects appeared to increase at nitrogen dioxide levels higher than 40 micro g/m(3) in the youngest age group and with a linear effect in the interval 20-60 micro g/m(3) for the oldest. An effect of all indicators on cardiovascular causes, lung cancer, and chronic obstructive pulmonary disease was also found in both age groups and sexes. The effects were particularly strong for chronic obstructive pulmonary disease, which appeared to have linear effects, whereas cardiovascular causes and lung cancer seemed to have threshold effects. Results show that vulnerable persons with chronic obstructive pulmonary disease and the elderly seem to be susceptible to air pollution at lower levels than the general population.

Divestment of foreign production operations
Gabriel R.G. Benito
1997· Applied Economics223doi:10.1080/00036849700000027

This study investigates some determinants fo the divestment of foreign manufacturing operations by Norwegian companies. To date, very few studies have taken a closer look at what might influence whether foreign subsidiaries are divested or not. Although foreign direct investment – in principle – represent long-term commitments to foreign manufacturing operations, divestments are in fact quite common. This study shows that more than half of a sample of foreig subsidiaries woned by Norwegian companies in 1982 wee divested within a period of ten years. The empirical findings indicate that foreign divestment is inversely related to economic growth in the host country, and that the propensity to divest is significantly higher for subsidiaries that had been acquired than for greenfield establishments. Also, related (horizontal) subsidiaries are less likely to be divested than unrelated (non-horizontal)subsidiaries.

Worldwide evaluation of mean and extreme runoff from six global-scale hydrological models that account for human impacts
Jamal Zaherpour, Simon N. Gosling, Nick J. Mount, Hannes Müller Schmied +4 more
2018· Environmental Research Letters180doi:10.1088/1748-9326/aac547

Global-scale hydrological models are routinely used to assess water scarcity, flood hazards and droughts worldwide. Recent efforts to incorporate anthropogenic activities in these models have enabled more realistic comparisons with observations. Here we evaluate simulations from an ensemble of six models participating in the second phase of the Inter-Sectoral Impact Model Inter-comparison Project (ISIMIP2a). We simulate monthly runoff in 40 catchments, spatially distributed across eight global hydrobelts. The performance of each model and the ensemble mean is examined with respect to their ability to replicate observed mean and extreme runoff under human-influenced conditions. Application of a novel integrated evaluation metric to quantify the models' ability to simulate timeseries of monthly runoff suggests that the models generally perform better in the wetter equatorial and northern hydrobelts than in drier southern hydrobelts. When model outputs are temporally aggregated to assess mean annual and extreme runoff, the models perform better. Nevertheless, we find a general trend in the majority of models towards the overestimation of mean annual runoff and all indicators of upper and lower extreme runoff. The models struggle to capture the timing of the seasonal cycle, particularly in northern hydrobelts, while in southern hydrobelts the models struggle to reproduce the magnitude of the seasonal cycle. It is noteworthy that over all hydrological indicators, the ensemble mean fails to perform better than any individual model-a finding that challenges the commonly held perception that model ensemble

The Scope of Action for Local Climate Policy: The Case of Norway
Carlo Aall, Kyrre Groven, Gard Lindseth
2007· Global Environmental Politics152doi:10.1162/glep.2007.7.2.83

One of the key features of the post-Rio era has been how global environmental governance is mediated between local, national and global levels of government. In this article, we draw on experiences from local climate policy planning in Norway in order to discuss the ways in which climate change enters into a municipal policy setting. Based on the Norwegian case, supplemented with knowledge gained from an international literature review, we present a typology of six different categories of local climate policy. We highlight that local actors can both play the role as a structure for the implementation of national or international climate objectives, as well as that of being policy actors taking independent policy initiatives. We emphasize how the relationship between national and local authorities is a crucial factor if climate policy as a specific local responsibility should be further strengthened.

Application of physics-informed neural networks to inverse problems in unsaturated groundwater flow
Ivan Depina, Saket Jain, Sigurður Már Valsson, Hrvoje Gotovac
2021· Georisk Assessment and Management of Risk for Engineered Systems and Geohazards123doi:10.1080/17499518.2021.1971251

This paper investigates the application of Physics-Informed Neural Networks (PINNs) to inverse problems in unsaturated groundwater flow. PINNs are applied to the types of unsaturated groundwater flow problems modelled with the Richards partial differential equation and the van Genuchten constitutive model. The inverse problem is formulated here as a problem with known or measured values of the solution to the Richards equation at several spatio-temporal instances, and unknown values of solution at the rest of the problem domain and unknown parameters of the van Genuchten model. PINNs solve inverse problems by reformulating the loss function of a deep neural network such that it simultaneously aims to satisfy the measured values and the unknown values at a set of collocation points distributed across the problem domain. The novelty of the paper originates from the development of PINN formulations for the Richards equation that requires training of a single neural network. The results demonstrate that PINNs are capable of efficiently solving the inverse problem with relatively accurate approximation of the solution to the Richards equation and estimates of the van Genuchten model parameters.

A novel method for the quantification of tire and polymer-modified bitumen particles in environmental samples by pyrolysis gas chromatography mass spectroscopy
Elisabeth S. Rødland, Saer Samanipour, Cassandra Rauert, Elvis D. Okoffo +4 more
2021· Journal of Hazardous Materials115doi:10.1016/j.jhazmat.2021.127092

Tire and road wear particles may constitute the largest source of microplastic particles into the environment. Quantification of these particles are associated with large uncertainties which are in part due to inadequate analytical methods. New methodology is presented in this work to improve the analysis of tire and road wear particles using pyrolysis gas chromatography mass spectrometry. Pyrolysis gas chromatography mass spectrometry of styrene butadiene styrene, a component of polymer-modified bitumen used on road asphalt, produces pyrolysis products identical to those of styrene butadiene rubber and butadiene rubber, which are used in tires. The proposed method uses multiple marker compounds to measure the combined mass of these rubbers in samples and includes an improved step of calculating the amount of tire and road based on the measured rubber content and site-specific traffic data. The method provides good recoveries of 83-92% for a simple matrix (tire) and 88-104% for a complex matrix (road sediment). The validated method was applied to urban snow, road-side soil and gully-pot sediment samples. Concentrations of tire particles in these samples ranged from 0.1 to 17.7 mg/mL (snow) to 0.6-68.3 mg/g (soil/sediment). The concentration of polymer-modified bitumen ranged from 0.03 to 0.42 mg/mL (snow) to 1.3-18.1 mg/g (soil/sediment).

Occurrence of tire and road wear particles in urban and peri-urban snowbanks, and their potential environmental implications
Elisabeth S. Rødland, Ole Christian Lind, Malcolm J. Reid, Lene Sørlie Heier +4 more
2022· The Science of The Total Environment110doi:10.1016/j.scitotenv.2022.153785

According to estimates put forward in multiple studies, tire and road wear particles are one of the largest sources to microplastic contamination in the environment. There are large uncertainties associated with local emissions and transport of tire and road wear particles into environmental compartments, highlighting an urgent need to provide more data on inventories and fluxes of these particles. To our knowledge, the present paper is the first published data on mass concentrations and snow mass load of tire and polymer-modified road wear particles in snow. Roadside snow and meltwater from three different types of roads (peri-urban, urban highway and urban) were analysed by Pyrolysis Gas Chromatography Mass Spectrometry. Tire particle mass concentrations in snow (76.0–14,500 mg/L meltwater), and snow mass loads (222–109,000 mg/m2) varied widely. The concentration ranges of polymer-modified particles were 14.8–9550 mg/L and 50.0–28,800 mg/m2 in snow and meltwater, respectively. Comparing the levels of tire and PMB particles to the total mass of particles, showed that tire and PMB-particles combined only contribute to 5.7% (meltwater) and 5.2% (mass load) of the total mass concentration of particles. The large variation between sites in the study was investigated using redundancy analysis of the possible explanatory variables. Contradictory to previous road studies, speed limit was found to be one of the most important variables explaining the variation in mass concentrations, and not Annual Average Daily Traffic. All identified variables explained 69% and 66%, for meltwater and mass load concentrations, respectively. The results show that roadside snow contain total suspended solids in concentrations far exceeding release limits of tunnel and road runoff, as well as tire particles in concentrations comparable to levels previously reported to cause toxicity effects in organisms. These findings strongly indicate that roadside snow should be treated before release into the environment.

What explains the performance of community-based initiatives? Testing the impact of leadership, social capital, organizational capacity, and government support
Malika Igalla, Jurian Edelenbos, Ingmar van Meerkerk
2019· Public Management Review95doi:10.1080/14719037.2019.1604796

Community-based initiatives (CBIs) are thriving in Western countries. In CBIs, citizens take a leading role in providing public services and goods. CBIs have been acclaimed for their innovativeness, problem-solving capacity, and legitimacy. However, we lack large N studies on performance of CBIs and its antecedents. This article develops and tests a model that identifies relationships between performance and four antecedents by using survey data on CBIs collected in the Netherlands (N = 671). Using structural equation modelling, positive direct and indirect relationships between transformational leadership, boundary spanning leadership, organizational capacity, social capital ties, government support, and performance are found.

What Determines Decision‐Makers’ Preferences for Road Investments? Evidence from the Norwegian Road Sector
James Odeck
2010· Transport Reviews84doi:10.1080/01441640903138640

Abstract What determines decision‐makers’ preferences for road projects has been a subject of debate in the transport economics literature for decades. Because economic assessments of road projects are conducted subject to demands by decision‐makers in almost all western European countries and the USA, it should be expected that they use these assessments in one way or another to determine the preferred portfolios of projects. This paper attempts to reveal the preference of decision‐makers with respect to road investment projects to be included in the Norwegian National Transport Plan for the period 2002–11. The decision‐makers are the Norwegian parliament members. The basis for considering each individual project for investment is the Impact Assessment sheet containing monetized and non‐monetized impacts that will accrue to society if a project is implemented. The dataset comprises a pool of 1121 independent projects, of which 184 were selected for investment. We hypothesize different models that may explain decision‐making using a multinomial logit model. The preferred model shows that most of the variables determining decisions are actually included in the traditional benefit–cost analyses (BCAs), except that the decision‐maker takes account of them in non‐monetary units rather than in a composite benefit–cost ratio or net present value. Further, among the government’s three stated objectives of efficiency, safety and regional development, only safety is found to be significant in the preferred model. These results support other previous studies to the extent that a BCA per se does not matter in decision‐making, but its components matter in a non‐monetized form.

Characterization of tire and road wear microplastic particle contamination in a road tunnel: From surface to release
Elisabeth S. Rødland, Ole Christian Lind, Malcolm J. Reid, Lene Sørlie Heier +4 more
2022· Journal of Hazardous Materials83doi:10.1016/j.jhazmat.2022.129032

Road pollution is one of the major sources of microplastic particles to the environment. The distribution of tire, polymer-modified bitumen (PMB) and tire and road wear particles (TRWP) in different tunnel compartments were explored: road surface, gully-pots and tunnel wash water. A new method for calculating TRWP using Monte Carlo simulation is presented. The highest concentrations on the surface were in the side bank (tire:13.4 ± 5.67;PMB:9.39 ± 3.96; TRWP:22.9 ± 8.19 mg/m2), comparable to previous studies, and at the tunnel outlet (tire:7.72 ± 11.2; PMB:5.40 ± 7.84; TRWP:11.2 ± 16.2 mg/m2). The concentrations in gully-pots were highest at the inlet (tire:24.7 ± 26.9; PMB:17.3 ± 48.8; TRWP:35.8 ± 38.9 mg/g) and comparable to values previously reported for sedimentation basins. Untreated wash water was comparable to road runoff (tire:38.3 ± 10.5; PMB:26.8 ± 7.33; TRWP:55.3 ± 15.2 mg/L). Sedimentation treatment retained 63% of tire and road wear particles, indicating a need to increase the removal efficiency to prevent these from entering the environment. A strong linear relationship (R2-adj=0.88, p < 0.0001) between total suspended solids (TSS) and tire and road wear rubber was established, suggesting a potential for using TSS as a proxy for estimating rubber loads for monitoring purposes. Future research should focus on a common approach to analysis and calculation of tire, PMB and TRWP and address the uncertainties related to these calculations.

High levels of tire wear particles in soils along low traffic roads
Elisabeth S. Rødland, Lene Sørlie Heier, Ole Christian Lind, Sondre Meland
2023· The Science of The Total Environment75doi:10.1016/j.scitotenv.2023.166470

Traffic pollution has been linked to high levels of metals and organic contaminants in road-side soils, largely due to abrasion of tires, brake pads and the road surface. Although several studies have demonstrated correlations between different pollutants and various traffic variables, they mainly focused on roads with medium to high traffic density (>30,000 vehicles per day). In this study we have focused on investigating tire wear particles and road-related metals (zinc, copper, lead, chromium, nickel, and the metalloid arsenic) in the soils of low traffic roads in rural areas (650-14,250 vehicles per day). Different explanatory factors were investigated, such as traffic density, speed, % heavy vehicles, organic matter content, annual precipitation, soil types and roadside slope profiles. The results show high levels of tire wear particles, from 2000 to 26,400 mg/kg (0.2-2.6 % tire wear in d.w. soil), which is up to five times higher compared to previously reported values in roadside soils of high traffic density areas. A weak but significant correlation was found between tire wear particles, traffic speed and the annual precipitation. No significant relationship was found between tire wear particles metals. The concentrations of metals were comparable to previous studies of high traffic areas of Norway, as well as both urban and rural soils in other countries. For the metals, all factors together explained 45 % of the variation observed, with traffic density (11 %) and organic matter content (10 %) as the most important single variables. The analysis of tire wear particles in soils using Pyrolysis Gas chromatography Mass Spectrometry is challenging, and the results presented demonstrate the need for pretreatment to remove organic matter from the samples before analysis.

When is SFT competitive?
Håvard Østlid
2010· Procedia Engineering74doi:10.1016/j.proeng.2010.08.003

When is a Submerged Floating Tunnel competitive?The various elements in transport systems are most often selected on the basis of the lowest price for the alternatives being viaducts, bridges or tunnels or some combinations of these. The submerged floating tunnel will therefore have to compete with well known structures and therefore have a disadvantage since no submerged floating tunnel has yet to be built. A future owner is then faced with a risk not easily estimated on one hand, on the other hand this new alternative may have certain attractive features especially when environmental considerations become important. This paper presents these various advantages and also points out some obvious disadvantages with this new and challenging structure. A great step forward would be if a submerged floating tunnel were built somewhere. The proposed structure here in China would certainly generate a lot of interest and I suggest the involved parties should prepare for a large number of visitors.

On the internal blast loading of submerged floating tunnels in concrete with circular and rectangular cross-sections
Martin Kristoffersen, Arianna Minoretti, Tore Børvik
2019· Engineering Failure Analysis74doi:10.1016/j.engfailanal.2019.04.074

The Norwegian Public Roads Administration has initiated a large research project on a potential ferry-free coastal highway route E39 on the west coast of Norway. For the wide and deep fjords, a submerged floating tunnel (SFT) in reinforced concrete has been suggested as a possible solution. A potential hazard for such a structure is internal blast loading, which can be devastating to its structural integrity. To assess the blast performance of concrete structures, a shock tube has been used to generate blast loading against concrete slabs with and without reinforcement. The shock tube tests were filmed with high-speed cameras, and digital image correlation was used to measure the out-of-plane deformations. A finite element model using input from material tests was set up in ABAQUS/Explicit to recreate the slab experiments. Based on the models validated by the shock tube experiments, full-scale numerical simulations of blast loaded SFTs with circular and rectangular cross-sections were run. The results were used to assess the qualitative performance of each cross-section geometry with respect to blast loading, where the circular cross-section indicated a superiour behaviour.

Protein Kinase C-mediated Interphase Lamin B Phosphorylation and Solubilization
Philippe Collas, Larry J. Thompson, Alan P. Fields, Dominic Poccia +1 more
1997· Journal of Biological Chemistry71doi:10.1074/jbc.272.34.21274

Disassembly of the sperm nuclear envelope at fertilization is one of the earliest events in the development of the male pronucleus. We report that nuclear lamina disassembly in interphase sea urchin egg cytosol is a result of lamin B phosphorylation mediated by protein kinase C (PKC). Lamin B of permeabilized sea urchin sperm nuclei incubated in fertilized egg G1 phase cytosolic extract is phosphorylated within 1 min of incubation and solubilized prior to sperm chromatin decondensation. Phosphorylation is Ca2+-dependent. It is reversibly inhibited by the PKC-specific inhibitor chelerythrine, a PKC pseudosubstrate inhibitor peptide, and a PKC substrate peptide, but not by inhibitors of PKA, p34(cdc2) or calmodulin kinase II. Phosphorylation is inhibited by immunodepletion of cytosolic PKC and restored by addition of purified rat brain PKC. Sperm lamin B is a substrate for rat brain PKC in vitro, resulting in lamin B solubilization. Two-dimensional phosphopeptide maps of lamin B phosphorylated by the cytosolic kinase and by purified rat PKC are virtually identical. These data suggest that PKC is the major kinase required for interphase disassembly of the sperm lamina.

Acute effects and exposure to organic compounds in road maintenance workers exposed to asphalt
Tor Norseth, Jostein Waage, Inge Dale
1991· American Journal of Industrial Medicine61doi:10.1002/ajim.4700200604

Subjective symptoms and exposure to organic compounds were recorded in road repair and construction workers. Abnormal fatigue, reduced appetite, laryngeal/pharyngeal irritation, and eye irritation were recorded more often in such workers handling asphalt than in a corresponding reference group without asphalt exposure. Mean daily exposure to volatile compounds was only occasionally above 1 ppm. Mean exposure to asphalt fume was 0.358 mg/m3. There was no correlation between symptoms and total amount of volatile compounds, but a significant positive correlation was demonstrated between symptoms and some substances. The highest correlation was found for 1, 2, 4 trimethyl benzene. Symptoms increased with increasing asphalt temperature and with increasing concentrations of asphalt fumes. Amine addition did not increase the sum of symptoms, but soft asphalt seems to result in fewer symptoms than the harder types. Symptoms were not related to external factors like weather, traffic density, or specific working operations. As preventive measures, asphalt temperature should be kept below 150 degrees C, fume concentrations below 0.40 mg/m3, and if possible, the use of harder asphalt types which also require high temperatures should be avoided.

A field deployable, multiplexed Bragg grating sensor system used in an extensive highway bridge monitoring evaluation tests
Y.M. Gebremichael, W. Li, B. T. Meggitt, W.J.O. Boyle +4 more
2005· IEEE Sensors Journal57doi:10.1109/jsen.2005.846185

A multiplexed optical fiber Bragg grating sensor system with a measurement bandwidth of up to 200 Hz enabling dynamic loading events, e.g., road traffic, to be observed has been designed, installed, and tested over an 18-month period on a 346-m road bridge in Norway, for design verification and structural integrity monitoring purposes. A network of 32 fiber Bragg sensors was surface bonded along with a corresponding set of resistive strain gauges for comparative tests to be made. The wavelength data were calibrated against two thermally stabilized (/spl sim/0.15 pm) reference gratings, which rejected common mode noise and provided absolute wavelength scaling. These data provides independent strain and temperature information. Long-term test results showed good linearity and repeatability of <10 /spl mu//spl epsiv/ over the test period with a precision of /spl plusmn/5 /spl mu//spl epsiv/ and a resolution of /spl plusmn/1 /spl mu//spl epsiv/. The readings from the FBG sensors were comparable to those from the foil gauge sensors to within /spl plusmn/4 /spl mu//spl epsiv/.

Metagenomic evidence of a novel family of anammox bacteria in a subsea environment
Carolina Suarez, Paula Dalcin Martins, Mike S. M. Jetten, Sabina Karačić +4 more
2022· Environmental Microbiology54doi:10.1111/1462-2920.16006

Bacteria in the order 'Candidatus Brocadiales' within the phylum Planctomycetes (Planctomycetota) have the remarkable ability to perform anaerobic ammonium oxidation (anammox). Two families of anammox bacteria with different biogeographical distributions have been reported, marine Ca. Scalinduaceae and freshwater Ca. Brocadiaceae. Here we report evidence of three new species within a novel genus and family of anammox bacteria, which were discovered in biofilms of a subsea road tunnel under a fjord in Norway. In this particular ecosystem, the nitrogen cycle is likely fuelled by ammonia from organic matter degradation in the fjord sediments and the rock mass above the tunnel, resulting in the growth of biofilms where anammox bacteria can thrive under oxygen limitation. We resolved several metagenome-assembled genomes (MAGs) of anammox bacteria, including three Ca. Brocadiales MAGs that could not be classified at the family level. MAGs of this novel family had all the diagnostic genes for a full anaerobic ammonium oxidation pathway in which nitrite was probably reduced by a NirK-like reductase. A survey of published molecular data indicated that this new family of anammox bacteria occurs in many marine sediments, where its members presumably would contribute to nitrogen loss.

Influence of jaw crusher parameters on the quality of primary crushed aggregates
Marit Fladvad, Tero Onnela
2020· Minerals Engineering53doi:10.1016/j.mineng.2020.106338

A parameter study using a jaw crusher is designed to investigate the influence of feed gradation, feed rate, crusher setting and crusher speed on the crusher operation and the quality of the produced aggregates. The study is focused on the production of all-in large-size (top size ⩾90 mm) aggregates, suitable for use in subbase and frost protection layers in a pavement structure. Aggregate quality is measured in terms of product gradation, particle shape and mechanical properties. Feed gradation, crusher setting and crusher speed affects the specific energy consumption during crushing. Particle shape is affected by all parameters; feed gradation, feed rate, crusher setting and crusher speed. Mechanical properties are least affected by the jaw crusher parameters, but sample preparation using laboratory crushing clearly affect mechanical properties. The results from this study provide valuable knowledge for the optimisation of single-stage crushing regarding crusher operation and aggregate quality. By adapting the crushing process to the available feed material and desired product, the quality of the crushed product can be optimised along with the crusher operation.

Laser-arc hybrid welding of 12- and 15-mm thick structural steel
Ivan Bunaziv, Cato Dørum, Steen Erik Nielsen, Pasi Suikkanen +4 more
2020· The International Journal of Advanced Manufacturing Technology53doi:10.1007/s00170-020-05192-2

Abstract High-power lasers are very effective in welding of plates thicker than 10 mm due to the keyhole mode. High-power intensity generates a vapor-filled cavity which provides substantial penetration depth. Due to the narrow and deep weld geometry, there is susceptibility to high hardness and weld defects. Imperfections occur due to keyhole instability. A 16-kW disk laser was used for single-pass welding of 12- to 15-mm thick plates in a butt joint configuration. Root humping was the main imperfection and persisted within a wide range of process parameters. Added arc source to the laser beam process may cause increased root humping and sagging due to accelerated melt flow. Humping was mitigated by balancing certain arc and other process parameters. It was also found that lower welding speeds (&lt; 1.2 m/min) combined with lower laser beam power (&lt; 13 kW) can be more positive for suppression of humping. Machined edges provided more consistent root quality and integrity compared with plasma cut welded specimens. Higher heat input (&gt; 0.80 kJ/mm) welds provided hardness level below 325 HV. The welded joints had good Charpy toughness at − 50 °C (&gt; 50 J) and high tensile strength.