The phrase "a key station" is correct and usable in written English.
It can be used to refer to an important or central location in a network, such as in transportation or communication contexts.
Example: "The city’s main transit hub serves as a key station for commuters traveling to and from the suburbs."
Alternatives: "a crucial station" or "an essential station".
One NATO official in Afghanistan spoke in stark terms about the attack, saying it had "effectively shut down a key station".
Since the closure of the U.S. Embassy in Damascus, in February , 2012 it has become a key station for coördinating Washington's Syria strategy.
Bamfield, British Columbia, was a key station on the fragile line of telegraph cables that kept London talking to its farthest-flung outposts.
Jiangsu Province that borders Auhui to the east is presumed as a key station for the spread of EV71 to other regions of the Yangtze River Delta.
But plans for Russian scientific experiments have been grounded by the country's recent decision to sell NASA thousands of hours of station time earmarked for research by Russian cosmonauts for $60 million needed to complete a key station component (Science, 9 October, p. 206).
The town of Kufra in Libya's distant southern desert is a long way from anywhere - historically it was a key trading station and place of rest for travellers between central and northern Africa.
It was also a key transit station on the trade routes from Rumelia (Ottoman possessions in the Balkans) to Anatolia.
It has begun to repair a key pumping station in the event the system needs to be drained to allow workers to fix it.
It's an unprecedented process, and a key weigh station in Venezuela's long road back, not just from elected autocracy, but from a subtle and pernicious disease of the public sphere: Chávez Derangement Syndrome.
Tajik authorities are notoriously thin-skinned about anyone prying into their fraught relations with ethnic minorities in Badakhshan, which happens to be a key weigh station on the drug trafficking route between Afghanistan and Russia.
But all of that did happen, because at some point someone decided that, on a relatively small island packed with people, a key power station should be located a couple hundred feet from a river, and until the folly of that decision was quite literally made brilliantly clear, it seemed foolish — too difficult, too expensive — to move it.
