Rachel Lowe, from Network Rail, said a minor defect in the rail was identified in an inspection on 12 November, and again on 21 November, but there was "no visible crack in the rail at all and it was managing within normal standards".

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Dr. Chaim Lotem said the hole, measuring 1 to 2 millimeters, is a minor birth defect found in 15 percent to 25 percent of people.

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