A key section of the Harbor (110) Freeway through downtown will be closed for six hours this morning in what Caltrans is calling a ``swarm maintenance'' of the downtown freeway.

Hundreds of Caltrans employees and other workers will be deployed between 6 a.m. and noon on about four blocks of the southbound 110 from Third Street to Wilshire Boulevard, according to Caltrans.

Transition ramps from both directions of the Hollywood (101) Freeway to the southbound 110 will be closed at the Four Level Interchange.

Southbound traffic from the Arroyo Seco Parkway segment of Route 110 will have just two through lanes. Ramps at Third and Fourth streets will also be closed.

``Nearly 300 Caltrans personnel will use this closure to perform necessary maintenance to improve the safety and aesthetics of the interchange and perform routine bridge inspections,'' Acting Caltrans District 7 Director of Maintenance Herby Lissade said, adding that nearly $150,000 will be saved by ``condensing several weeks of work into six hours.''