A form of Traffic Order, which traffic authorities have the power to impose without consultation. The powers to do so are contained in Section 9 of the Road Traffic Regulation Act 1984.
Once an ETO is in place, there is a statutory 6 month period in which objections must be considered, and within 18 months a decision must be made on whether to make the changes permanent. Without a decision the ETO lapses and the changes must be reverted.
ETOs have advantages over TROs/TMOs in that they allow changes to actually be trialled on the ground, to try things without having to initally face public opposition.