Today is the first weekday and back-to-work day for thousands of public transit riders who have to find a different way to get back and forth between Pittsburgh and the South Hills while the Palm Garden Bridge is closed for six months of repairs.

The bridge carries the South Busway and about half of all light-rail traffic over Route 51 to and from the city. The bridge was closed yesterday, but some service changes began Saturday because of pre-construction activities.

Port Authority spokesman Bob Grove said he was not aware of any problems over the weekend. The true test is expected to come today, when commuters head back to work. Customer service representatives are expected to get a heavier volume of calls, he said.

Information about changes has been posted at every trolley stop and at select bus stops.

Some of the major service changes include:

All South Busway buses will be detoured. Inbound stops at Edgebrook and Pioneer and inbound/outbound stops at Dawn, Palm Garden and South Hills Junction will be discontinued.

42S South Hills Village via Beechview service will be discontinued to Downtown but will provide shuttle service between Castle Shannon and Beechview. Riders can transfer to other T routes or temporary bus routes established at the Dormont station and other points. 47S South Hills Village via Overbrook service will be expanded to operate seven days a week at peak and off-peak times.

47L Library rail service will operate normally during weekday peak periods but will be replaced off-peak and on weekends with 44L Library Short service, which will operate between Library Station and Washington Junction. Customers may transfer there free of charge to or from 47S rail service.

44S Castle Shannon-Beechview will provide rail service between Overbrook Junction and Traymore in Beechview.

The 37D Dormont Station bus route will operate between Dormont Junction Station and Downtown Pittsburgh via Banksville Road during weekday peak periods.

The Port Authority is spending $9.4 million to rehabilitate the 30-year-old concrete and steel span that crosses Route 51 near the south end of the Liberty Tunnels.

The Port Authority customer service number is 412-442-2000. Information is also available at www.portauthority.org.