Context: Pre-project 2018
Worldwide, railway companies are being faced with increasing public and political pressure to reduce the environmental impact of their operations, particularly by cutting back on herbicide use. This needs to be done without jeopardising transport and personal safety, however. In addition to a number of other projects with this focus, the SBB (Swiss Federal Railways) has ordered a feasibility study (2nd semester of 2018) on the greening of railway rights-of-way.
A study of the literature revealed this research subject to be technical and scientific virgin territory, although ample experience that could serve as a reference point exists in related fields – viz. tramway greenturfs and the greening of roofs. An expert panel concluded that a greening of rights-of-way could be successful and would indeed offer potential ecological advantages, provided that safety risks were avoided.
The expert panel recommends comprehensive tests in field trials, in-situ under real conditions and ex-situ under controlled conditions. At the sites in question, several treatments will be evaluated in replications via two vegetation surveys per year.
Based on the feasibility study, 81 plant species that were likely meet the safety and ecological requirements of a rights-of-way greening were selected from among thousands of taxons occurring in Switzerland. Taking account of natural plant communities, four mixtures were then created which are now being tested in field trials.
Plant species and monitoring:
- Choice of potentially suitable plant species
- Creation of mixtures based on natural plant communities
- Observation of development via two vegetation surveys per year
After careful consideration, sites were chosen on the Swiss Plateau only, since this region has the highest-density rail network and since – in the event of the project’s successful conclusion – the greening would be implemented in this region first.
Field trials of different design on several sites:
- Experimental trials at three in-situ sites (three plant mixtures)
- Empirical trials at two in-situ sites (one plant mixture)
- Experimental ex-situ trials under controlled and semi-controlled conditions at one site (four mixtures)
Motto: “Sow rather than control”
- Check for successful plant establishment: Do these indigenous plants sown in mixtures establish successfully under special railway rights-of-way conditions?
- Check for successful suppression of competition: If the indigenous plants establish successfully, do they inhibit / suppress the growth of spontaneous vegetation, especially neophytes?
- Clarify safety aspects: If the plant species establish successfully, do they comply with operational safety criteria (height, root depth, accessibility etc.)?
- Identify the evolution of biodiversity: If establishment is successful, can it be assumed that the greening of the railway rights-of-way with indigenous plants will result in the connection of different habitats for indigenous fauna and flora, owing to the corridor effect?