PITTSBURGH — Sir Andrew Davis resigned as the artistic adviser of the Pittsburgh Symphony Orchestra, citing his increased workload as the music director of the Lyric Opera in Chicago.

Davis joined the Pittsburgh Symphony in September 2005 after musical director Mariss Jansons left. Davis resigned Friday with about a year left on his three-year contract, which ran through September 2008.

Davis headed a team that included principal guest conductor Yan Pascal Tortelier and endowed guest conductor Marek Janowski.

The orchestra announced in January that Manfred Honeck will become musical director in 2008, so Davis said he felt able to leave now.