Thresholds for infrastructure projects considered by the Planning Inspectorate

The thresholds for infrastructure projects that will be considered Nationally Significant Infrastructure Projects, as set out in the Planning Act 2008:

Power stations

  • In England or Wales; minimum 50 megawatts (MW) generating capacity if onshore; minimum 100 MW if offshore

Electric lines

  • In England or Wales, including lines that run into (but not within) Scotland
  • Above ground, minimum 132 kilovolts (kV) capacity

Underground gas storage / liquefied natural gas (LNG) facilities / gas reception facilities

  • In England and Wales; minimum 43 million cubic metres working capacity or 4.5 million cubic metres maximum flow rate


  • In England; minimum 800 millimetres diameter and minimum 40 kilometres (km) length


  • In England; trunk roads and motorways where the Secretary of State is or will be the highways authority


  • In England; will be capable of handling a minimum 10 million passengers per year or 10,000 movements of cargo
  • Extensions will need to increase airport capacity by at least 10 million passengers per year or 10,000 movements of cargo


  • In England and Wales; for container ships, a minimum 500,000 twenty-foot equivalent units (TEU); for roll on roll off (ro-ro) ships, minimum 250,000 units; for facilities for cargo ships of any other description, minimum 5 million tonnes.


  • Wholly in England; part of the railway network

Rail freight interchanges

  • In England; at least 60 hectares in area; at least 4 trains per day, from more than one consigner and consignee

Dams and Reservoirs

  • In England; more than 10 million cubic metres for new developments
  • An increase of more than 10 million cubic metres for extensions

Transfer of water resources

  • In England; more than 100 million cubic metres per year; not piped drinking water

Waste water treatment plants

  • In England; capacity exceeding a population equivalent of 500,000

Hazardous waste facilities

  • In England; if landfill or deep geological storage, 100,000 tonnes per year; in other cases, 30,000 tonnes per year
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