Sustainable Tram Track Structure
Design of a more durable and sustainable tram track structure on soft soil
R. van Noort (TU Delft - Civil Engineering & Geosciences)
Valeri Markine – Mentor (TU Delft - Railway Engineering)
RBJ Brinkgreve – Graduation committee member (TU Delft - Geo-engineering)
Z Yang – Graduation committee member (TU Delft - Railway Engineering)
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Abstract
In the borough of IJsselmonde in the city of Rotterdam, there are significant problems with the tram track geometry. The subsoil consists of soft soil types, such as peat and clay. At certain locations, settlements result in severe irregularities of the vertical alignment. At the roundabout at the Groeninx van Zoelenlaan, the track deflections are so severe that the protective shield underneath the front end of the tram touches the surface level and the emergency brakes are activated, which is very uncomfortable for the passengers. The tram track structure is only 18 years old, which is significantly lower than the intended life span of 30 years. This research aims to balance and optimise the sustainability and durability performance of the tram track structure and therefore, the following research question is defined: “To what extent can the durability and sustainability performance of a tram track structure on soft soil conditions be improved while preserving the vertical track geometry?”
PLAXIS 2D and PLAXIS 3D simulations are performed to investigate the structural performance of the tram track superstructure for the current situation and for a situation where light-weight filler materials are used. This study reveals that Rockwool, foam concrete and EPS are suitable as a foundation to reach the intended life span of 30 years. When considering the carbon footprint over 30 years, installing EPS and Rockwool result in a reduction of 3.4% and 1.5% respectively. Further CO2-reduction can be obtained when embedding the track in olivine ballast and producing rails from recycled steel in Electric arc Furnaces. This leads for a track built on Rockwool or EPS to a carbon footprint reduction of 72.3% and 74.4% respectively. When taking into consideration that Rockwool can be used as water buffer and therefore contributes to a more climate-resilient neighbourhood, this is considered to be the most sustainable alternative. So overall, when Rockwool and EPS are used, the sustainability and durability performance of the tram track structure on soft soil improves while preserving the vertical track geometry.