Cluster Transport, transport infrastructure | Umweltbundesamt

On the relevance of the action field

A modern industry and services-oriented society such as Germany is highly mobile. Most people travel on a daily basis; either they commute to their place of work, walk, cycle or drive to their school or training establishment. Likewise, they cover more or less long distances for recreation and for shopping purposes. The functioning of economic systems depends on reliable goods transport; this includes the transport of energy carriers and raw materials, operating materials and intermediate products, and the delivery of end products to sales outlets or delivery direct to the end customer.

Transport infrastructures and means of transportation are usually both directly exposed to weather conditions. Extreme weather and extreme weather patterns often go hand in hand with mobility disruptions, which in some cases, can threaten life and limb of transport users. In less threatening cases, disruptions take the form of slowing down or delaying traffic. In exceptional cases, transport links can become unavailable for extended periods such as weeks or months or even fail entirely as a result of damage to the infrastructure. Such restrictions to the mobility of goods and passengers can entail various economic consequences such as increased costs and losses incurred by companies, supply bottlenecks and shortages, or rising
prices for motor fuels and energy.

DAS Monitoring –what is happening due to climate change

In recent years, extreme weather and extreme weather patterns have repeatedly caused major disruptions in goods and passenger transport. These events are increasingly associated with changing climatic conditions thus indicating that impacts from climate change will affect both transport carriers such as road and rail, inland and marine shipping as well as air transport.

As far as goods transport by inland shipping is concerned, the Rhine and its tributaries play a major role in Germany. In excess of 75 % of goods transported by Germany’s inland shipping are conveyed via the Rhine. Floodwater events affect inland shipping whenever they exceed the highest navigation level (HSW) and when the relevant section of the river Rhine is completely blocked to shipping (cf. Indicator VE-I-1). In respect of Upper Rhine stretches, shipping was blocked on a total of 18 days in 2021 – the highest value since 1999. As far as Lower and Middle Rhine stretches are concerned, closures lasting for more than five days were the exception. In contrast, restrictions owing to low water levels can persist for considerably longer periods (cf. Indicator VE-I-2). Contrary to high-water level closures, inland shipping is usually still possible. However, in these cases, profitability depends on the permitted draught of the vessel concerned. In 2018 – a particularly hot and dry year – the highest number of low-water restrictions was recorded so far. Goods transport by inland shipping was only possible with restrictions on the Upper Rhine on 80 days and on well over 100 days on the Middle and Lower Rhine. Regarding the Lower Rhine, low-water restrictions have been increasing significantly since 1997.

Any adverse effects on road transport and damage to road infrastructures, that occurred in recent decades, were primarily due to hurricanes and flooding resulting from heavy rain and floodwater. In Germany, torrential rain events occur every year affecting between 5 to more than 30 % of federal trunk roads (cf. Indicator VE-I-3). This type of heavy rain events also played a role in the emergence of the floodwater disasters which created havoc in 2021. Even when they are less extreme, such downpours can impact road conditions and visibility thus increasing the risk of road accidents. However, in the course of the past 25 years, the severity of slippery road conditions caused by rain as a contributory factor in road accidents has been decreasing (cf. Indicator VE-I-4). As far as road maintenance services are concerned, the ímpacts of hurricanes Cyril (2007) and Xynthia (2010) have so far brought about the heaviest workloads. Nevertheless, some tempests involving storm, hailstones and heavy rain also inflicted heavy workloads, especially latterly in 2018 and 2021.

Such tempests are also relevant factors in terms of rail transport; they can adversely affect traffic flow or cause damage to infrastructures. Other relevant events are winter storms with heavy snowfall and drifting snow or inundations resulting from floodwater and heavy rain. In years of high heat exposure, adverse effects can result from breakdowns of technical components in track switch operation mechanisms and switch points, but they can also occur in the rolling stock. Another hazard is the vegetation on embankments catching fire; this too can entail restrictions (cf. Indicator VE-I-6).

Future climate risks – outcomes of KWRA

As far as the transport, transport infrastructure action field is concerned, the 2021 Climate Impact and Risk Analysis (KWRA) suggests that by the middle of this century, climate risk concerning low-water level issues regarding the navigability of inland waterways will be high. As far as other climate impacts such as damage to or obstacles on roads or railway lines resulting from floodwater or major gravitational mass movements are concerned, a medium climate risk has been identified by this analytical process to arise by mid-century. Likewise, with a view to traffic management systems, overhead wires and power supply systems, a medium climate risk has been identified. Nevertheless, it has to be said that these risk assessments are subject to considerable uncertainties.

Where do we have gaps in data and knowledge?

In addition to road transport and inland shipping, the 2023 Monitoring Report allowed for the first time the inclusion of a third transport carrier, and this concerns weather-related disruptions in the railway infrastructure. The issue of air transport has again not been included as a theme This is due to the fact that at the time when the DAS Strategy was first developed, various analyses showed that climate changes were expected to have only limited impacts on this sector¹⁵⁸. In the meantime, potential impacts of climate change on air transport have been examined more closely, both at national and international level, leading to the identification of various relevant themes which are being examined in cooperation with the DWD within the framework of effects research. On the basis of the outcome of these assessments it may be possible to expand the indicator set by incorporating the air transport theme¹⁵⁹. To date, another transport sector, i.e. public transport (ÖPNV) has been addressed only partly within the indicator on disruptions of the railway infrastructure. This is because there has so far been a lack of data and information on ÖPNV with a view to potential climate change impacts and adaptation measures required, to allow illustrating the theme within the indicator set.

Substantial impacts of climate change on transport include damage to transport infrastructures arising, in particular, from extreme weather events and consequential disruptions to traffic flow as well as accident risks. As far as road transport is concerned, data available from accident statistics allow a tentative approach to these themes. However, to render a clearer picture of the impacts of traffic flow, it would be necessary to obtain data on frequency and duration of traffic obstructions or congestions arising from causes such as heavy rain or storm. As far as the situation regarding road accidents is concerned, more in-depth information on potential impacts of summer heat and heat periods on driving behaviour and accident scenarios are required in order to bring the relevant indicator into sharper focus. For railway transport some of the data on disruption causes are not available in sufficient detail; for instance, in case of major disruptions, it is not possible to capture and record all the information required. In terms of DAS Monitoring, the indicator would be improved by incorporating the duration of disruptions.

In general, there is to date, in respect of all transport carriers, a shortage of systematically captured and evaluated data which would allow a quantitative description of the impacts of weather extremes on transport infrastructures. In respect of road, rail and shipping, it would be helpful to have cause-related information detailing, for instance, the costs of remedying damage or of maintaining infrastructures. The same applies to air transport infrastructures insofar as this theme will in future be integrated within the DAS Monitoring system. As a matter of principle, it would be desirable to have data available that allow a differentiated illustration of diverse regions such as floodplains, coasts or uplands in order to show their various vulnerabilities.

In the transport sector, it has not been possible so far to illustrate adaptation measures in terms of response indicators, although it is true to say that targeted adaptation activities are in progress for this action field. However, adaptation measures which are in the process of being carried out are, in many cases, beyond the scope of continuous data capture which would serve as a basis for regular illustration by means of indicators. This applies just as much to information-related measures such as offering data services, management tools or guidance notes as to regulatory measures such as the adaptation of technical standards and assessment bases. In order to facilitate the assessment of engineering measures such as the mitigation of problems in roads with poor drainage or safeguarding a minimum water level in waterways by means of river engineering, it would be desirable to introduce an ‘adaptation marker’ which would facilitate the allocation of targeted finance available for climate adaptation.

The expenditure required for measures to be carried out regularly for the operational management of transport infrastructures, such as maintenance-related dredging works in waterways or the management of vegetation on railway embankments, varies in accordance with a number of variables including climatic factors. Many of such measures will require adaptation to the challenges of climate change. For a quantitative illustration of the varying extent of such measures it is essential to ensure a differentiated capture of expenditure in terms of hours of work and costs. The illustration of operational measures for the optimisation of traffic flows and for temporal, spatial or intermodal relocation of passenger- and goods transports, would require a sophisticated assessment of fine-grained data on transport flows. This would require further research in order to obtain targeted guidance on suitable approaches to the development of monitoring indicators.

What’s being done – some examples

As far as the action field ‘transport, transport infrastructure’ is concerned at federal level, this is the remit of the BMDV. It is a superordinate objective of climate adaptation in the transport sector to safeguard the efficiency of the transport system vis-à-vis changing climatic challenges and more frequent extreme weather events, thus enabling the system to meet the future requirements raised by a mobile society. This objective is reflected in the BMDV’s strategic framework of departmental research in respect of the 20th parliamentary term under the motto ‘Transforming mobility sustainably and promoting digital efficiency’ (‘Mobilität nachhaltig transformieren und die digitale Leistungsfähigkeit vorantreiben’). This includes research activities to develop an infrastructure resilient to the impacts of climate change, developing adaptation measures for the improvement of data capture and forecasting, as well as the further development of alert message systems. Furthermore, the strategic framework incorporates the focal points ‘further development of digital applications’ and ‘resilient transport and data systems and transport safety’.

Starting in 2016, research activities have been bundled – insofar as they figured in the context of climate change impacts on the transport infrastructure and resulting adaptation requirements – under Theme 1 ‘Climate change impacts and adaptation’ of the BMDV‘s experts network ‘Knowledge – Skill – Action’. The network comprises seven superior authorities as well as the BMDV’s departmental research facilities who cooperate in the quest of finding solutions for substantial challenges and future issues in the field of transport and mobility. The involvement of the BMDV’s experts network in addressing the challenges – entailed by climate change – facing transport and the transport infrastructure, is defined as a measure embedded in the third action plan ‘Adaptation’ (APA III) adopted by Federal Government. Further measures under APA III addressed or supported by the BMDV’s experts network include the DAS basic service (Basisdienst) ‘Climate and Water’ – an operational data and advice service – as well as the Federal Waterways and Shipping Administration’s (WSV) strategy for adaptation to impacts of climate change on federal waterways and other related infrastructures, which is provided data by the DAS basic service, as well as the ‘Rhine low-water levels action plan’. Measures covering other transport carriers under APA III include the assessment of vulnerability of the railway transport networks and an evaluation of the adaptation of regulatory frameworks of the railway company DB Netz AG. With regard to road transport, APA III covers the promotion of extra investments into the road transport infrastructure within the framework of federal road transport planning. This is aimed at making the existing road transport infrastructure more robust against potential damage from extreme weather events. In future, a prognostic scenario entitled ‘extreme weather events 2080’ is to be incorporated in the planning process.

As far as railway transport is concerned, Federal Government, in its capacity of proprietor of Deutsche Bahn AG, is also active in terms of climate adaptation. Deutsche Bahn AG is currently in the process of developing a climate resilience strategy. The measures concerned include, for instance, optimised vegetation management along railway lines and the use of a more robust technology for track switch operation mechanisms or power units.

Other actors involved in climate adaptation in the transport sector are the Federal States (Länder) which address measures within the framework of their relevant competences. These measures span a wide range, from determining climate risks to transport routes to planning and implementation of actual engineering or management measures.

^{158 - Deutscher Bundestag (Hg.) 2008: Deutsche Anpassungsstrategie an den Klimawandel. Unterrichtung durch die Bundesregierung, Drucksache 16/11595. Berlin: 26. https://dserver.bundestag.de/btd/16/115/1611595.pdf.}

^{159 - DWD – Deutscher Wetterdienst (Hg.) o.J.: Klimawandel und Luftverkehr. https://www.dwd.de/DE/fachnutzer/luftfahrt/kufo/ein_kleiner_ausblick/klima_und_luftfahrt.html.}