Service on Port Authority buses will be "extensively detoured" this weekend due to street closures for the Dick's Sporting Goods Pittsburgh Marathon and related events, the transit agency announced today.

Additional service will also be implemented on the busways, inclines and light-rail systems for runners to get to the downtown starting line.

The agency will detour approximately 50 buses from the start of service and until about 3 p.m. during the full marathon. Riders should anticipate delays and allow for extra time.

Here's some more information from an advisory the agency sent out today:

— In Downtown, buses will be rerouted to stops near Steel Plaza T station, where riders may transfer to the T for free. Routes normally serving Squirrel Hill and Oakland will not serve Oakland during the marathon, but a free shuttle will be available to take riders between the neighborhoods. Riders heading to Children’s Hospital from Downtown can use the rerouted 64 Lawrenceville-Waterfront bus route, since the 88 Penn won't reach the hospital because of street closures.

— Additional, smaller detours will be in effect in Downtown and on the North Side on Friday and Saturday for marathon events.

— On Sunday, light rail service will begin around 4 a.m. and both inclines will open at 5 a.Riders should anticipate delays and allow for extra time.

For more information, visit the authority's marathon information page, or call Customer Service at 412-442-2000 (TTY 412-231-7007).