| 1. |
- Nilsson, Jan-Eric, et al.
(author)
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Funktionsupphandling : sammanfattning av kunskapsläge och rekommendationer för fortsatt forskning
- 2006
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Reports (other academic/artistic)abstract
- The Swedish concept "procurement of function" corresponds to performance contracting in Anglo-Saxon countries. The substance is that principal and agent signs a contract over the construction and maintenance of a specific project based on the services provided to future users, i.e. based on performance of the asset. This is in contrast with contracting base on technical qualities of the new road. VTI has reserved funds to provide an overview of current knowledge in this context. Four separate contributions, together with a short summary, are included in this report. One conclusion is that the experiences of this contractual form are much larger in other countries than in Sweden. We therefore have a lot to learn, not least from our closest neighbours Finland and Norway. International experiences indicate a large and growing interest in this form of contracting and provides reason for further development. A second conclusion is that Sweden in general and VTI in particular has important information of direct relevance for the development of efficient performance contracts. This knowledge must, however, typically be structured and organised along other lines than when the original research was undertaken. The institute should therefore seek to adapt the collection of information of relevance for performance contracts so that it fits in to this new framework. This includes issues such as the measurement of road surface quality and assessment of the additional costs for providing better surface quality on the one hand and the user benefits of improved quality on the other.
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| 2. |
- Afridi, Amjad, et al.
(author)
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Management of municipal street network in Sweden : results from a national survey
- 2024
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In: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 395-396
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Conference paper (other academic/artistic)abstract
- Management of street networks is different from state roads due to its multifunctional role in society. This requires timely maintenance of the street network to improve socioeconomic development. Municipalities in Sweden are responsible for the management of about 42000 km of street network in their jurisdiction. Maintenance budget and resources vary from municipality to municipality depending on their network size, geographical location, and population density. A questionnaire was sent to all 290 municipalities across the country to investigate the street network and pavement management practices at the municipal level. An in-depth interview of 14 municipalities took place afterwards. A total of 51% of responses were officially received to highlight the frequently and infrequently occurring pavement distresses and their causes. Furthermore, the study highlights the maintenance approaches and allocation of budget to manage the street network. Lastly, the study highlights the factors which need to be addressed to improve street network management. Visual assessment of pavements is common and the use of pavement management system (PMS) is not only limited but also lacks pavement performance prediction models. Common pavement distresses are excessive formation of potholes, surface unevenness and alligator distress among the municipalities. Frequent causes of distress include the ageing of the street network, heavy vehicles, patching and high traffic flow. Furthermore, cold climate and population density are important factors in the degradation process. Allocation of maintenance and reconstruction budget is relatively high in municipalities located in the north. Densely populated municipalities have higher taxpayers’ contributions to maintenance and reconstruction. Other major issues are limited resources and maintenance of budget, which adversely affect the maintenance backlog and the choice of maintenance alternatives, ultimately the decision-making. This restricts the use of preventive maintenance among the municipalities. Municipalities are required to improve the frequency and quality of pavement data collection, enhance the sophistication of PMS by using pavement deterioration models, and increase the maintenance budget and resources. An insight into the capabilities of municipalities would help in long-term strategic planning and effective utilisation of the maintenance budget to improve the street network across the country.
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| 3. |
- Afridi, Muhammad Amjad, et al.
(author)
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Municipal street maintenance challenges and management practices in Sweden
- 2023
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In: Frontiers in Built Environment. - : Frontiers Media S.A.. - 2297-3362. ; 9
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Journal article (peer-reviewed)abstract
- The municipal street network acts as a multifunctional asset by providing people, vehicles and public services with a well-functioning infrastructure. To keep it in good condition, optimal maintenance measures are required which would result in an efficient use of taxpayers' money. This paper investigates the street network deterioration processes and the management practices that the municipal administrations have applied in Sweden. The study is based on a survey with Swedish municipalities using questionnaires and complementary interviews. The answers provide insight into a wide range of common pavement distresses and deterioration factors, along with pavement management practices. The study identifies that potholes, surface unevenness and alligator cracking are the most cited challenges, while pavement ageing, heavy traffic and patches are the most noted causes. Similarly, the cold climate and population density are influential factors in pavement deterioration. Allocation of the maintenance and rehabilitation and reconstruction budget is higher in the northern part of the country as well as in densely populated municipalities. Condition data collection and use of commercial Pavement Management Systems (PMS) are limited. Addressing the challenges effectively may be possible through the enhancement of the budget, feasible/clear guidelines from municipal councils/politicians, and reducing the gap between street network administrations and utility service providers.
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| 4. |
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| 5. |
- Alfredsson, Magnus, et al.
(author)
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Funktionskriterier för vägkonstruktioner : Förstudie
- 2010
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Reports (other academic/artistic)abstract
- Det projekt som här rapporteras har som syfte att identifiera och beskriva de svårigheter och möjligheter som totalentreprenader medför, respektive erbjuder, för alla parter. Målet är att utveckla totalentreprenader på ett sådant sätt att branschens effektivitet ökas. Denna rapport är en förstudie där det studerats vilka krav som byggherren ska ställa på utföraren av en vägkonstruktion i en totalentreprenad med funktionsansvar och hur utföraren ska verifiera kraven. Arbetet har genomförts med medlemmar från olika aktörer i branschen och omfattat främst litteraturstudier och intervjuer. Kunskaper och erfarenheter har sammanställts och analyserats för att slutligen kondenseras ned till ett antal förslag till fortsatt arbete.Förstudien har pekat ut ett antal områden som viktiga för att påskynda framtida utveckling av totalentreprenader:Terminologi – idag råder viss begreppsförvirringAnalys av funktionella krav i tidigare projektTrafikantkravMiljökravUtveckling av funktionella krav i samverkanVäghållarekonomiRegelbetingade begränsningar av funktionella kravUppföljning och underlättande av erfarenhetsackumuleringImplementering av nya mått och mätmetoder
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| 6. |
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| 7. |
- Anund, Anna, 1964-, et al.
(author)
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Deliverable Nr 4 – Consistent treatment in relation to the severity of a curve, a driving simulator study
- 2011
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Reports (other academic/artistic)abstract
- The overall aim of this work is to develop guidelines for evaluation of potential treatments, categorized as “self-explaining treatments” by the use of a driving simulator. More specific the driving simulator study had the aim:• To evaluate the effectiveness of curve treatments, in particular to determine whether a combination of treatments on curves according to their severity could help drivers correctly establish the severity of a curve in advance, and therefore adapt their speed appropriately.In total 35 participants, divided into two groups, drove approximately 46 minutes on a rural road with 3 baseline curves without treatment and 9 curves with treatment of varying levels. In total three different treatment levels and three different curves were used. One group received treatments before each curve that correspond to the severity of the curve (slight curve – low treatment level; moderate curve – medium treatment level; severe curve – high treatment level); the other group experienced inconsistent treatments by being exposed to all nine possible combination of curve and treatments.The analysis of the effects on speed in average and at each point (v0 to v5) was done with Mixed Model ANOVA. Dependent variables were speed measurements in the different points along the curve (v0 to v5) and the average speed through the total curve (from point v0 to v5). The analyses were done both for absolute speeds and for the relative change in speed from starting point (v0). Independent variables were consistent/inconsistent group; curve (1-3), treatment level (1–3) and time on task, here called order (1–9). Subject was used as random and nested on group. In addition the most severe curve was analysed separately in order to compare the groups.In conclusion the result showed that in most cases there were significant effects for treatment levels, severity of the curve, order (time on task), and for subject. There was no significant main effect on group (consistent/inconsistent). However, there was an interaction between curve and group, telling us that the consistent marking significantly reduced the average speed among those with consistent treatment. This holds true also for the speed at point v2, v3 and v5. A final argument for the effectiveness of consistent treatment is that if only the severe curve was considered, there was a significant effect of group.Guidelines for evaluationIt was found that our used method to evaluate the effects of speed adjustment worked well. 35 participants each drove approximately 45 minutes. They were divided into a consistent and one inconsistent group. Three levels of treatment and three severities of curves were used. The dependent variable was the speed measured at three points along the curve. This methodology could be used to evaluate other types of self-explaining treatments. But since a driving simulator study requires a lot of planning (expensive) it is suggested to initially do an expert workshop to evaluate and select the suitable SER treatment and also detailed scenario description.
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| 8. |
- Arnberg, Peter W., et al.
(author)
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The Laser RST : Current status
- 1991
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Reports (other academic/artistic)abstract
- Efficient and well-maintained road systems are necessary for the economic well being of any industrialized country. Maintenance and rehabilitation of existing roads have taken priority over new construction in recent years, thus making information about the condition of road surfaces extremely important. Several methods of gathering this information have been developed worldwide; one of them is Laser Road Surface Tester (Laser RST), which was developed in Sweden in 1981. The Laser RST is a laser-based, computer-automated, non-contact road profilometer system with the ability to collect and simultaneously process data about the road surface. Variables measured include rut depth, unevenness, cracking, megatexture, rough macrotexture, fine macrotexture, crossfall, curves, and elapsed distance. Subjective evaluations are also supported, if desired. Eleven laser rangefinders (LRFs), mounted on the front of the Laser RST van, are the primary components of the data collection system. They scan the road with high-speed, high-resolution distance sampling. The signals from the lasers are sent through signal processing cards (SPCs) and then to a computer inside the van for final processing. Data is stored on floppy disk and printed by an on-board printer. The Laser RST is an extremely complex system but it is also a modular one, making troubleshooting and repair relatively easy, inexpensive, and fast. This paper discusses the various modules available. Variables measured are defined and measurement algorithms detailed. The Laser RST system can be customized to meet specific user requirements quickly and easily.
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| 9. |
- Arvidsson, Anna K., 1971-, et al.
(author)
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Åkkvalitet på vinterväg
- 2014
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Reports (other academic/artistic)abstract
- Denna VTI-studie konstaterar att det går att mäta ojämnheter på vinterväg på samma sätt som på barmarksväg. Både ojämnheter och buller vid låga frekvenser ökar vid visst vinterväglag och är kopplade till hastighet. De mätningar som utförts inom projektets ramar visar att det går utmärkt att utföra mätningar på en snöklädd yta. Med vinterväglag menas här en snöklädd väg cirka ett dygn efter ett kraftigt snöfall. Baserat på de vägar som mättes visar studien att ojämnheter i våglängdsintervallet 0,05 till 1 meter påverkas allra mest av vinterväglaget. Ojämnheterna ökar cirka 5 gånger i medeltal för hela testslingan från barmarks- till vinterförhållanden. Det går även att se att ytans struktur, som beskrivs av de kortaste våglängderna som undersöktes, <10 mm, blir slätare på den snöklädda ytan vilket var en av hypoteserna och som indikerar att mätningen är pålitlig. Kopplingen mellan buller och ojämnheter är relaterade till hastighet. Den största ljudskillnaden mellan vinter- och sommarväg var vid låga frekvenser. Det uppfattade ljudet i bilen var då mellan 3 och 6 decibel högre för körningen på vinterväg. I de mer högfrekventa områdena var skillnaden i ljudnivå tvärtom, lägre för vintervägen än för sommarvägen och en trolig orsak till detta kan vara att ljudet absorberas av snön.
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| 10. |
- Asp, Leif, et al.
(author)
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Delamination Growth and Thresholds in a Carbon/Epoxy Composite under Fatigue Loading
- 2001
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In: Journal of composites technology & research. - 0884-6804 .- 1945-7537. ; 23:2, s. 55-68
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Journal article (peer-reviewed)abstract
- This paper presents a study on delamination growth in Mode I, Mode II and mixed mode under fatigue loading in an HTA/6376C composite. The computed slopes of the modified Paris plots were high. Therefore, threshold values of the strain energy release rate for delamination growth were determined. Low fatigue threshold values revealed a significant effect of fatigue loading. The largest effect was found for the ENF test (Mode II) for which the fatigue threshold value was only 10% of the critical strain energy release rate in static tests. Threshold values for MMB (mixed mode) and DCB (Mode I) tests were 15% and 23% of the static values, respectively. Fractographic evaluation revealed identical initial failure mechanisms in fatigue and static loading conditions for the ENF specimen. The ENF specimen failed by formation and coalescence of microcracks. The low fatigue threshold for the ENF specimen was explained by microscopical observations on the specimen edge. It was also shown that the fracture surfaces generated in static and fatigue DCB and MMB tests were similar.
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