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Understanding Dredging


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How to Manage Light Emissions to Avoid Migratory Songbird Collisions at an Offshore Construction Site

€ 20,-


Presented during:

WODCON XXIII - Dredging is changing - The Practice. The Science. The Business.


U. Zeidler, G. Nehls, S. Bräger, V. Kosarev, J. Flamme


"Birds migrating across offshore areas at night under certain weather conditions become attracted by artificial light and approach and even collide with vessels. In order to mitigate these effects during the construction of an Immersed Tunnel across the Fehmarnbelt between the Danish island of Lolland and the German island of Fehmarn, the German Plan Approval decision requires light mitigation measures and monitoring of the bird collision risks during the migration periods. It requires an Environmental Construction Inspection (ECI) to oversee the following mandatory measures as outlined in an official light management concept. The Fehmarnbelt Tunnel is the first Project required to implement a light management for offshore construction works to protect nocturnal bird migration. As it proved to be a challenging task to coordinate this Project over several years with over 50 work vessels, a new approach was developed by ECI together with the Project Owner and the Contractors how these obligations can be fulfilled: The core of the approach is the self-monitoring of the construction vessels and the relevant vessel crews are trained to respond to events when birds approach the vessels at night. ECI monitors bird migration by two far-reaching weather-radar stations and it identifies conditions which might lead to an increased collision risk. Crews are then informed through evening warnings sent to all project vessels. This presentation shows how a supervised self-control of the Contractor can fulfil the requirements on light management to protect bird migration and evaluate the approach based on first experiences of five months of migration."

Keywords: bird migration, collision risk, crew induction, light management, self-monitoring, offshore construction



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