Question: when did network rail take over from railtrack
[{'answer': '2002', 'provenance': [{'wikipedia_id': '26081', 'title': 'Railtrack', 'start_paragraph_id': 1, 'start_character': 187, 'end_paragraph_id': 1, 'end_character': 191, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '26081', 'title': 'Railtrack', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 589, 'bleu_score': 0.9531501622378341, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11250539650901749095}, 'section': 'Section::::Abstract.'}]}]