PHILADELPHIA - Closed roads, limited train service and metal detectors that pedestrians are required to pass through will complicate travel in downtown Philadelphia as preparations begin for Pope Francis' weekend visit.

A vehicle ban around the sites of Francis' major events will remain in effect through the weekend. Some streets were closed Friday morning for use only by emergency vehicles. They include: Vine, 22nd, Lombard and Market, east of City Hall.SEPTA's regional rail line is operating on a Saturday schedule and its Suburban Station will be closed. Subway service also is altered. The Market-Frankford line stations at 5th and 15th streets and the Broad Street line's City Hall station will be closed. The 15th Street trolley station will also be closed.Additional transit restrictions go into effect Saturday.A secure perimeter going into effect around the Benjamin Franklin Parkway and City Hall will mean pedestrians must pass through metal detectors to access certain parts of downtown beginning Friday morning.Other restrictions will take effect later Friday.At 6 p.m., vehicles won't be allowed to enter a nearly 5-square-mile area of downtown. Driving will be permitted within the zone, but cars won't be let back in after leaving.At 10 p.m., the nearly 2-mile-long Benjamin Franklin Bridge between Camden, New Jersey, and Philadelphia and 25 miles of highway will be shut down.Interstate 76 will be closed eastbound from I-476 to I-95 and westbound from I-95 to U.S. Route 1. Interstate 676, known as the Vine Street Expressway in downtown Philadelphia, and 2 miles of U.S. Route 1 near where Francis is expected to stay, also will close.A security zone around Independence Mall will go into effect at that time as well.The vehicle-free perimeter went into effect Thursday night. Three exits on the cross-city Vine Street Expressway also were closed.The roads are expected to reopen by Monday morning.Organizers expect about 500,000 people for a festival and concert featuring Francis on Saturday and more than a million people at his Mass on Sunday, both on the parkway.About 40,000 people are expected for the pope's speech on immigration and religious freedom at Independence Mall on Saturday.Access to a section of the parkway between 20th Street and where Francis' altar is being built at Eakins Oval will be restricted until Saturday morning.For the papal events on Saturday, metal detectors will open at 6 a.m., about 3 hours before Francis is scheduled to land at Philadelphia International Airport.