Context: Airport construction boomed during the 1960s with the increase in jet aircraft traffic. Runways were extended out to 3,000 m (9,800 ft). The fields were constructed out of reinforced concrete using a slip-form machine that produces a continual slab with no disruptions along the length. The early 1960s also saw the introduction of jet bridge systems to modern airport terminals, an innovation which eliminated outdoor passenger boarding. These systems became commonplace in the United States by the 1970s.

Question: Why did airport construction boom during the 1960s?
Answer: increase in jet aircraft traffic

Question: How far were runways extended out?
Answer: 9,800 ft

Question: What was constructed out of reinforced concrete?
Answer: The fields

Question: When were jet bridge systems introduced to modern airport terminals?
Answer: early 1960s

Question: In what year was there a boom in jet bridge systems?
Answer: Unanswerable

Question: How far were jet bridge systems extended to?
Answer: Unanswerable

Question: When was using reinforced concrete a common practice in the US?
Answer: Unanswerable

Question: What did airport construction eliminate in the 1970's?
Answer: Unanswerable

Question: What were jet bridge systems made of?
Answer: Unanswerable