Question: when did the chesapeake bay bridge-tunnel officially open for traffic
[{'answer': 'April 15 , 1964', 'provenance': [{'wikipedia_id': '885929', 'title': 'Chesapeake Bay Bridge–Tunnel', 'start_paragraph_id': 1, 'start_character': 1048, 'end_paragraph_id': 1, 'end_character': 1063, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '885929', 'title': 'Chesapeake Bay Bridge–Tunnel', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 1218, 'bleu_score': 0.8529174273755401, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15665029560269398945}, 'section': 'Section::::Abstract.'}]}]