This paper presents an interdisciplinary research programme in context with the reliability of transport infrastructures. The programme initiated by the German Federal Ministry of Transportation and Digital Infrastructure (BMVI) aims at understanding the underlying risk-driving factors, their indicators and resulting decision criteria. Using the example of the federal waterways in Germany illustrates the innovative approach.
The condition of the German transport infrastructure is increasingly deteriorating due to a variety of reasons. The reliability of the infrastructure is thus perceived as a risk factor for private and commercial enterprises. Actual figures substantiate this perception showing an immense maintenance backlog. Hence, there is an urgent need for new methodological approaches and innovative techniques to find adequate strategies in coping with the actual situation and future challenges. Thus, the BMVI initiated the innovative interdisciplinary research programme “BMVI Network of Experts” pooling the expertise and skills of its departmental research facilities and executive agencies.
As technical advisor to the BMVI, the Federal Waterways Engineering and Research Institute (BAW) is part of this network. The research activities of BAW consider the particular requirements of the waterway infrastructure. The waterway infrastructure features a high diversity and large number of structures. Thus, the determination of meaningful structural indicators is essential for an efficient prioritisation of maintenance measures. In combination with other data sources like geographic information systems, such indicators allow an estimation of the consequences for environmental, social and economic values located close to waterways. The knowledge about the consequences evokes an increasing demand for new technologies helping to reduce both the actual impact of disruptive events on the infrastructure and the potential risks of failure scenarios. Hence, innovative maintenance methods are studied and adapted for usage in waterways.
Amongst others, the interdisciplinary research activities in the “BMVI Network of Expert” show first results regarding several aspects of the structural reliability of waterway infrastructures:
- Essential risk factor is the precision in the prediction of extraordinary events and the subsequent control of the resulting effects. The development process of a smart discharge and water level control for navigable waterways aiming at minimizing the effects of such events shows the benefits of a close cooperation between institutions providing competences in meteorology, hydraulic engineering and control technology. Heavy precipitation can cause large water level variations in impounded rivers, as urban runoff from impervious surfaces is discharged to the receiving waters almost immediately. Given a discharge prediction of several hours, the local control system of the effected weirs calculates the ideal set value of the water level using optimization procedures. In this way, water discharge surges are homogenized, which improves the safety of shipping and adds to the reliability of affected structures.
- The detailed, i.e. quantitative, assessment of the structural reliability is a complex task and considered unfeasible when dealing with a large number of structures. In the field of mechanical engineering, qualitative methods are often used to assess the reliability of processes and products on a more general level. These methods are fairly unknown to civil engineers but prove beneficial in analysing inspection data and expert knowledge. The widely used Failure Mode and Effect Analysis (FMEA) was adapted to make use of data already available in the maintenance management system of the BAW. The FMEA was enhanced with fuzzy logic-based evaluation methods providing comprehensive key figures for a comparative risk assessment on a large number of structures. Such qualitative risk assessment then helps in the decision process about further actions like installing a smart water level control in order to reduce the water load variation on river weirs.
- Assessing deterioration processes and damage development are crucial parts of a reliability analysis. Both they depend on strongly varying initial and boundary conditions. In this regard, the elicitation and usage of available expert knowledge is indispensable. The advantages of so-called guided expert interviews are presented using the example of the design process for a full-scale embankment model test. The interviews were conducted to analyse the long-term damage development of loose riprap embankments. Based on results of the expert interviews, the model test was designed. The model was finally erected in the wave basin of the BAW, which allows observing degradation caused by hydraulic loads after initial damage.
The presented projects demonstrate the benefits of interdisciplinary research approaches. The results achieved so far add profound and comprehensive information to the ongoing discussions about efficient investment and effective maintenance strategies. In this way, the research activities of the BAW contributes to the urgently required reduction of the maintenance backlog and, eventually, to a reliable, highly available infrastructure.