If you live west of Downtown, pay close attention to bus route changes.

The first phase of construction on the outbound ramp of the Fort Pitt Bridge and the 10th Street Bypass to Fort Duquesne Boulevard will turn Downtown into even more of a public transit tangle. When it all starts Thursday, a substantial number of Port Authority riders will face shifting stops and detours to get out of the Golden Triangle.

Service is being affected because the ramp from the 10th Street Bypass and Fort Duquesne Boulevard to the Fort Pitt Bridge will be closed for up to three months because of restrictions around the West End Circle.

Bus riders on 20 routes have been advised to expect delays in travel times, mostly in the outbound direction, but the Port Authority isn’t predicting the length of the delays.

"We don’t think anybody knows at this point," authority spokesman Bob Grove said. "We think it will take about a week for things to settle down and for us to learn what to expect."

The changes will affect, "basically, all of the western part of Allegheny County," said Fred Mergner, an authority planner.

Coming Downtown will not be as problematic as getting out.

During construction, some stops Downtown, in the West End and on Carson Street will temporarily be discontinued and moved to other streets.

Commuters using buses to get to the Duquesne Incline from Downtown must use routes 21A-B-C-D-F.

To prepare riders for the change, the Port Authority has begun distributing yellow stop/change cards, and notices at bus stops will appear soon.

For now, the Port Authority has no plan to alter trolley service. It expects to be able to accommodate ridership increases for passengers hoping to avoid driving into Downtown without adding cars or trips.

The Port Authority is pushing its 34 park-n-ride sites as an alternative. The sites, which offer free parking, are as far out as Indiana Township and hold 4,816 parking spaces. Plans are under way to expand the Castle Shannon, Washington Junction and South Hills Village T-stations in the South Hills by 1,370 spaces. In the east, at the lot on Route 48 at East Allegheny High School, plans are under way to add 20 spaces.

For the past three years, the Port Authority has been engaged in a $6 million program to expand facilities. In the works are 25 additional park-n-ride sites with more 6,000 spaces. Among the locations are Rankin and Neville.

Staff writer Joe Grata contributed to this report.