Port Authority's West Library park-and-ride lot will shut down Sunday and remain closed through Oct. 28.
The lot is being temporarily used to store equipment so Port Authority can replace the nearby Latimer Bridge, which carries the light-rail line over a stream.
Commuters can instead park at the nearby Library Station park-and-ride lot, which normally has about 100 empty spaces on weekdays, the Port Authority said.
Other alternate parking spots for light-rail transit commuters include the Lytle lot in Bethel Park and the South Hills Village garage.
The West Library "T" station on the Library Blue Line will remain open for those who walk except for two periods -- the last weekend of September and another weekend in October that has not been announced.
For the duration of the project there will be single-track service between the Mesta and Sarah stops that could lead to some delays during peak hours.