LECTURES
The objective of good scientific presentations is to bring the recipients closer to complex interrelationships from one's own research and at the same time to enable a dialogue about these as well as the validation and further development of the ideas and contents presented. The selection of presentations below shows a small selection of the range of topics covered by Hoffmann Consult.
Pavement and Asset Management
HOFFMANN, M. (2021); Innovative Pavement Management with Life Cycle Costs; Invited lecture Aachen Road Construction and Traffic Days (SETAC); Aachen [German]
The presentation gives an overview of the standard approaches used worldwide and in the German-speaking countries in pavement management, as well as the common simplifications and resulting limitations. Based on the digital condition assessment and damage evaluation with algorithms, it will be shown how significant improvements can be achieved in concrete terms with an innovative approach to individual damage management and optimization by means of economies of scale in the life cycle. The methods shown were developed in over 10 years of research together with Valentin Donev. In my habilitation, it is shown how these innovative methods can be applied to bridges and tunnels providing proof for the applicability of the developed innovative methods to any complex, aging, and repairable system.
Road Operation and Winter Maintenance (EN)
HOFFMANN, M. & GRUBER, M. & HOFKO, B. & STINGLMAYR, D. & SEIFRIED, T. & GROTHE, H. & SCHOEN, A. (2022); WINTERLIFE – Effective, sustainable and non-corrosive de-icing agents in winter maintenance, accepted paper with a presentation, XVI World Winter Service and Road Resilience Congress 07-11 February 2022, Calgary 2022
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With an average of 20 to 30 snowfall days and 40 to 70 days with hoarfrost and freezing rain in Austria, winter maintenance is one of the most important tasks to provide transport infrastructure at a high level of safety and availability. The quick removal of ice and snow with grit and de-icing agents is, therefore, a priority on road and rail to guarantee high customer satisfaction. However, commonly used de-icing agents like sodium chloride (NaCl) are highly corrosive, therefore significantly reducing the service life of infrastructure assets. To avoid these drawbacks, the rail operator OEBB-INFRA, BMK, and FFG provided funding for the search and development of alternative de-icing agents. The main criteria are thawing performance, low application rates and costs, minimal corrosion, and negative effects on humans, animals, and plants. The research project WINTERLIFE from Hoffmann-Consult and TU Wien draws on extensive research projects in the field of winter maintenance. Based on literature and market research all principal de-icing agents are analyzed regarding freezing curves, thawing capacity, costs, and availability. The cost-efficiency comparison of these de-icing agents is based on the costs for thawing the same amount of snow/ice and is being used as selection criteria for further analysis. In the next step, the corrosion of deicers with/without corrosion inhibitors is tested with spray and immersion tests on copper, steel, and galvanized steel plates. Drawing from these results the environmental impacts and usability of the most promising combinations are included as well in a holistic life-cycle analysis. The research project and paper provide an overview of all relevant criteria and results of the analysis as well as recommendations for selecting an optimal de-icing agent in winter maintenance for relevant use cases. In summary, it is possible based on the research results to select the optimal de-icing agent and/or additives for a wide range of use cases.
Travel time gains VS time constancy - an irresolvable contradiction?
HOFFMANN, M. (17/5/2022); Contribution to the workshop of the Research Society Road, Rail, Transport (FSV) on the evaluation of high-priority road construction projects in Austria - Methodological discussion of suitable evaluation approaches and procedures of decision support tools.
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Abstract: Transport infrastructure enables the achievement of the basic functions of existence and economic relationships between locations as well as participation in resources, products, and uses in a common market. The resulting market and price advantages from economies of scale and concentration tendencies are offset by expenses for the provision of transport infrastructure, resource consumption, and environmental impacts. Every improvement of a mode of transport in terms of costs, travel time, efficiency, and comfort, therefore, has a corresponding impact on market share (modal split) and increases transport volume and transport distance. Systematic analyses of the investment environment, boundary conditions, and trends are therefore the basis for a holistic evaluation of investments in transport infrastructure. In Europe, the sovereign approval procedures for transport infrastructure include correspondingly formalized proof of economic viability and environmental compatibility. In these proofs, the time gained between connected locations is considered to be a significant benefit of the expansion of transport infrastructure. In contrast, with reference to time expenditures for mobility that have remained approximately constant in total for decades, it is argued that there are no relevant time savings and thus benefits in the transport system. As the literature analysis and empirical data show, both the time savings between locations after expansion and the approximately constant time expenditures for mobility in the system over the long term can be demonstrated.
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Resolving this contradiction, or consistent assessment of benefits and costs and their distribution is therefore essential for decision making. Using a location-theoretic model and empirical data, it can be shown that expansion projects reduce transportation costs, increase efficiency, and largely translate the time saved into accessibility benefits. The centralized production and division of labor is the basis of location competition via economies of scale, the driver of globalization, and largely results in consumer returns. These welfare gains with diminishing marginal utility can be consistently demonstrated on the basis of data analysis of all countries in the world. The argument of a general lack of benefit from expansion projects due to approximately constant time expenditures in the system is therefore just as untenable as the focus on local time gains from individual projects. Rather, expansion leads to a concentration in competitive agglomerations and a depletion of peripheral areas of people, jobs, and opportunities. Thus, expansion is also not equally beneficial to all connected locations, regions, and agglomerations. The resulting environmental impacts and resource consumption are not adequately reflected in standard economic feasibility studies, nor in national accounts. Accordingly, this lack of cost truth leads to unsustainable developments in rural and urban agglomerations as well as transport systems worldwide yielding high external costs. In summary, what is needed is a more comprehensive view of planning, the development of better assessment methods, and concrete implementation at all levels that goes beyond non-binding targets. A possible path towards this goal can be a focus on economic returns as benefits compared to costs of expansion, operation & maintenance, and external costs to the environment & society based on circular economic appraisal in the life cycle.
Hoarfrost in Winter Maintenance - Measurement, Prediction & Control
HOFFMANN, M. & DONEV, V. (13/11/2022); Hoarfrost in Winter Maintenance - Measurement, Prediction & Control; Invited Lecture Winter Service Talks Tulln; Austria
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Abstract: Winter maintenance is a key task of road operators for ensuring accessibility and safety during the winter period from early November to late April every year. With an average of 15 to 25 snowfall events and 40 to 60 days with hoarfrost in Austria, the key challenge is choosing an optimal strategy with timing, application rates, and share of brine for each treatment run. Based on extensive research the key findings regarding measurement, prediction, and control of hoarfrost in winter maintenance are presented. In general, the condensation of water vapor to ice on surfaces at temperatures below freezing is considered hoarfrost. However, for the development of efficient winter maintenance strategies the key parameters for a prediction of hoarfrost events have to be identified. According to the literature, high relative humidity, decreasing temperatures below freezing, moderate wind speeds, and cloud cover are relevant weather parameters. In addition, previous research has shown a sharp decrease in skid resistance at moderate levels of ice cover between 50 to 200 g/m2 of ice [Karlsson, A. (2006); Horton, S. et al. (2014)]. In the research projects WINTERFIT I to III for the highway company ASFINAG a prototype hoarfrost sensor has been developed allowing continuous measurement and analysis of hoarfrost events in combination with a weather station. The statistical analysis has shown that the forming of hoarfrost is a continuous process starting between 22:00 to 01:00 in the evening and reaching a peak between 7:00 to 9:00 in the morning. The typical weather conditions are decreasing temperatures between -1°C to -6°C at high relative humidity levels above 88% with an ice mass of 50 to 150 g/m2. For the predictive winter maintenance of ASFINAG, several models (logistic regression, ANN) have been developed allowing forecasting of future events with 88 to 92% accuracy. Together with the winter maintenance model, it is now possible to simulate both hoarfrost events and their impact on skid resistance without treatment and all possible treatment strategies. The optimization is based on the efficiency of treatments regarding the achieved increase in skid resistance. The results have shown the positive effects of a preventive treatment between 22:00 to 0:00 with 10 g/m2 (FS50). In case of severe hoarfrost events, the second treatment between 3:00 to 6:00 in the morning with 10 g/m2 (FS50) is recommended. As an alternative one or two treatment runs with 20 g/m2 of brine (FS100) can be chosen. In contrast, a late treatment in case of a missed event in the morning will take considerable amounts of salt with inferior results regarding road safety. Currently, the prediction models are implemented into the maintenance decision-support software (MDSS) of ASFINAG, providing the basis for reliable predictions and optimization of winter maintenance strategies for all weather events on the entire highway network. The final validation of all models with extensive grip tester measurements will be completed in winter 2022/2023.
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Keywords: Weather events, hoarfrost events, skid resistance, prediction models, preventive salting
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Acknowledgments: The development of the winter maintenance model, the prototype hoarfrost sensor, and the prediction models for real-time road conditions, and the predictive winter maintenance tool would not have been possible without the generous support and contributions of ASFINAG..
