It was a big week for one of San Francisco’s busiest streets: On Wednesday much of Market Street -- a thoroughfare cutting right through the heart of the city’s downtown -- made the switch from car friendly to car free with with new rules banning all private traffic. On this edition of KCBS In Depth we take a look at how the first day of this car free conversion went and then examine where the broader movement for pedestrian-friendly cities might be headed next.  Guests:  Stan Bunger, anchor for KCBS Radio Holly Quan, reporter for KCBS Radio Karen Philbrick, executive director of the Mineta Transportation Institute at San Jose State University Marta Lindsey, communications director for Walk San Francisco Host: KCBS Radio reporter Keith Menconi