PORTLAND, Ore. (AP) -- Portland International Airport is beginning a runway improvement project that managers say will keep the airport fully operational while minimizing the noise impact on neighbors.

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An Alaska Airlines plane takes off from the airport.

The major improvements to the airport's two primary runways will begin May 1 with the first phase of the extension and rehabilitation of the north runway.

The extension from the current 8,000 feet to 9,827 feet will make the runway long enough to serve large passenger and cargo aircraft, including international flights to Europe and Asia, when the 11,000-foot south runway closes for rehabilitation in 2011.

The Port of Portland is mailing postcards and placing newspaper advertisements to prepare area residents for the construction project.

Flight delays are not expected, and airlines may adjust their schedules if necessary.