Transport infrastructure: beyond rail and road

Comparisons of greenhouse gas (GHG) balances of different means of transport are mostly limited to emissions, which are caused by the operation of the vehicles concerned – in effect, the direct emissions from the combustion of fuel (e.g. petrol, diesel, kerosene) in the vehicles and the indirect energy-related emissions caused by the generation, conversion, distribution and supply of the energy sources.

Raw materials like concrete, steel and copper that are used in the construction of transport infrastructure and the vehicles themselves have often been left out of GHG balances. A comprehensive analysis of the environmental impacts of different modes of transport, however, should not only consider the emissions of the energy sources used, but also emissions arising from vehicle manufacture and infrastructural needs.

Research projects on transport infrastructure

Alongside a comprehensive and up-to-date comparison of different modes of transport requiring transport infrastructure, researchers at Oeko-Institut are also focusing, in several current research projects, on the possible future design of transport infrastructure and the question of how to establish a transport infrastructure that is fit for the future.

The following problems are at the centre of Oeko-Institut’s research in this field: the high demand for resources needed by transport infrastructure; secondary raw materials that can be used in road construction; changing framework conditions such as the influence of demographic change, the influence of climate change and climate protection measures and the costs of different infrastructure systems. Furthermore, the researchers are also examining the demands on the energy supply infrastructure for the transport sector which have changed as a result of new drive technologies.

Comprehensive GHG balance of road, rail and air transport and shipping

How environmentally friendly is a journey by rail compared to a journey by motorway or air? What share does the use of modes of transport have compared to infrastructure such as that for roads, rail and airports? What would the results of an integrated sustainability impact assessment of different means of transport be?

One of Oeko-Institut’s current research projects compares the GHG emissions of different means of transport and aims to answer these questions. The analysis – conducted on behalf of the German Federal Environment Agency – arrives at the conclusion that the construction of infrastructure and vehicles accounts for approx. 10-30 % in the GHG balance of road, rail, air and shipping transport. As a result, the researchers found that rail and coach are still the most environmentally friendly means of passenger transport, even when the construction of roads, airports, rail etc. is included in the overall GHG balance.

Specific focus on GHG emissions of transport

The incorporation of the transport infrastructure and vehicle manufacture in the overall GHG balance and the focus on the kilometres / tonne kilometres travelled in freight transport results in a comprehensive and differentiated overview of the specific greenhouse gas emissions. For example: Travelling long distances by car produces the highest GHG emissions at 166 grams of CO2-equivalent (CO2e) per kilometre; approx. 20 grams originate from infrastructure and the vehicles.

Rail transport has the largest share of infrastructure- and vehicle-related emissions at approx. 20 grams of CO2e, but its overall emissions (approx. 71 grams) are 57 per cent below those of passenger cars. In terms of air transport (domestic flights within Germany), 27 grams of CO2e of alone is caused by the construction and operation of vehicles and infrastructure and overall 260 grams arises per kilometre flown. The operation of airports alone makes up approx. eight per cent of the emissions.

Sustainable design of transport infrastructure: further research needed

How can transport infrastructure in Germany be designed in the long term so that it uses as few resources as possible and meets future challenges such as those related to demographic and structural change, the consequences of climate change and the scarce financial resources of local authorities?

Oeko-Institut is tackling this question in the “Resource-efficient infrastructures that are fit for the future: environmentally-friendly, robust and demographically inclusive” project, which is being conducted in cooperation with the German Institute for Urban Studies based on scenario analyses up to 2050. The goal of the project is to provide recommended policy actions for establishing environmentally-friendly infrastructures.

Another research project – for which Oeko-Institut is cooperating with ifeu Heidelberg Institute for Energy and Environmental Research – focuses on the potentials for replacing primary raw materials in road and street construction with mineral waste and excavated soil. The project analyses the material flows and potentials of alternative building materials in the construction of new and existing roads and the dismantling and repair of existing roads.

Furthermore, the researchers are currently elaborating an expert strategy for the energy supply of the transport sector up to 2050. Together with INFRAS AG in Bern and the DVGW Research Centre at the Engler-Bunte Institute in Karlsruhe, Oeko-Institut is comparing the costs of different forms of energy supply such as the electric current for battery-powered vehicles, electricity-based fuels and hydrogen up to 2050. All three projects are being conducted by Oeko-Institut on behalf of the German Federal Environment Agency.