halt is a test technique called test-to-fail, where a product is tested until failure. here the steam turns back into a liquid which then cools the water. his tenure is normally for 3 years. these passages were at a higher level than before, so the bottom landings of the lifts and the emergency stairs were raised by  to match them. they had been working near high-frequency equipment all day. all double deck carriages have two doors per side per carriage, with a vestibule at each end at platform height. 