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.

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.

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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