Environmental impact of railway development: The Standard Gauge Railway in Tanzania

Abstract

Current railway activities in Africa suffer from poor track condition and lack of maintenance, but there is potential for rail transport growth for both passengers and freight. The aim of this thesis is to evaluate the environmental impact of a railway development in Africa.

The Standard Gauge Railway (SGR) in Tanzania, a railway line currently under construction, was identified as a relevant rail system to study from a life cycle perspective. Materials and energy requirements were collected and estimated from various sources of information to build a model representing the SGR (the SGR-model). A life cycle assessment (LCA), methodology used to evaluate environmental impacts, was conducted for this SGR-model. Rolling stock, its operation, and infrastructure were evaluated over 60 years of operation. To cover several types of environmental damages resulting from the construction and operation of the railway line, eight impact categories have been included in this environmental assessment.

The operation phase was found to have the highest contribution to climate change, fossil depletion, particulate matter formation, and terrestrial acidification. These impacts essentially come from the use of fossil fuels in the electricity supply mix. When analysing environmental impacts of the infrastructure, materials stood out as having the highest contribution to freshwater eutrophication, mineral resource depletion, and human toxicity. The use of steel and copper in the track and power and signalling system are the main contributors to these impacts. In addition, several other activities have also been identified as contributing significantly to environmental impacts of the infrastructure: transport of materials by lorry, land clearance as well as land transformation. Regarding the rolling stock, goods wagons generate most of its environmental impacts.

Scenarios based on the LCA model have been developed. Several electricity supply mixes were investigated, lifetime of railway components (sleepers, rails, and pads) and goods wagons was extended, use of secondary steel was introduced in the maintenance phase, and transport of materials was decreased. Results indicate that increasing the share of renewables in the electricity supply mix leads to the most significant impact reduction in climate change, fossil depletion, particulate matter formation and terrestrial acidification. Despite having a more limited impact reduction, the use of secondary steel and lifetime extensions have the potential to reduce freshwater eutrophication, human toxicity, and mineral resource depletion impacts. A combination of these various strategies is therefore suggested to improve the overall environmental performance of the SGR in Tanzania.