BALTIMORE (AP) — Maryland state transportation officials are warning drivers to avoid the Baltimore Harbor Tunnel this summer as a $3.9 million construction project gets underway.

Beginning June 20, motorists are expected to encounter rush-hour and weekend delays of up to an hour as construction crews replace the concrete decking on a four-lane bridge south of the Interstate 895 tunnel toll plaza. The work will be done in four phases and is expected to be completed in October.

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Engineers believe the worst delays will come during the first two weeks of August, when the two southbound lanes close and two-way traffic shifts onto the renovated northbound lanes.

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The Maryland Transportation Authority is urging motorists to use the Francis Scott Key Bridge or Fort McHenry Tunnel during the construction project.

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