Any assessment of navigation must take into account the movements of both commercial and recreational vessels. Tidal lagoons have to consider the shipping lanes, ports and locations of any areas used for recreation within the assessment to ensure that all potential impacts have been considered.

The construction, operation and decommissioning of a tidal lagoon can potentially affect navigation via increased transit times due to:

  • the physical presence of the structure
  • increased collision risk due to reduced maneuvering space (physical presence of the structure) resulting from increased current speeds
  • indirect effects such as changes to the tides and sediment deposition impacting port access and navigation channels.

There is a plethora of existing data which can be used to gain a better understanding of the existing environment in terms of navigation and, in order to support this, additional Automatic Identification System (AIS) and radar surveys can be undertaken within a project’s study area. These surveys collect data on the vessel traffic within the given area and inform assessment of the likely impacts of any development.

Tidal Lagoon Swansea Bay

The Severn Estuary is an important shipping area with large ships from national and international destinations using the estuary’s ports and anchorages. In order to inform the assessment of Tidal Lagoon Swansea Bay, Tidal Lagoon Power commissioned a 14 day marine traffic survey (14 to 28 August 2013) using Automatic Identification System (AIS) data with the addition of radar/Automatic Radar Plotting Aid (ARPA). This was supplemented by observations of vessels within visual range from the shore based survey crew. Additionally, AIS data was gathered over 56 days (28 days in July 2012 and 28 days in October 2012). This time period was used to gather representative winter and summer data for the assessment and is an accepted Maritime and Coastguard Agency (MCA) method.

Case Study

Tidal Lagoon Plc


T: +44 (0)1452 303892

A: Pillar & Lucy House
Merchants Road
The Docks

Tidal Lagoon (Swansea Bay) Plc


T: +44 (0)1792 274006

A: 8th Floor
One Central Square
CF10 1FS

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