Changes in Material Stocks and Flows of a Century-old Rail Network Caused by Refurbishment

The main objective of the paper at hand is to investigate material flows and stock changes of subway infrastructure associated with its refurbishment. Specific attention is given to the relation between recycling, reuse and virgin material flows. Furthermore, the extent to which policy targets are achieved in a specific refurbishment process is investigated. Thereto the refurbishment of a subsection of Vienna’s subway network was chosen as a case study. To fulfil the objective, a bottom up material flow analysis (MFA) of the refurbishment process on the subsection was performed. Results show that the overall material stock is 360,000 t, of which three-fourths remained unchanged within the refurbishment. Within the refurbishment process, in total material with a mass of around 155,000 t was built into the system. The share of recycling material was significantly higher than the use of virgin material. In detail 39% virgin construction material, 15% recycling construction material, 41% on site-recycling construction material and 5% reuse construction components were built into the section.