seven lanes of I-76, and carries approximately 120,000 vehicles per day. Connecting to Northeast Philadelphia are the Betsy Ross Bridge, a six-lane bridge linking the Bridesburg neighborhood of Philadelphia with Pennsauken, New Jersey, and the Tacony–Palmyra Bridge, a three-lane drawbridge spanning the Delaware River between the Tacony neighborhood of Philadelphia and Palmyra, New Jersey. Schuylkill River The Schuylkill River, a main tributary of the Delaware River, is crossed by 20 roads in Philadelphia. The oldest bridges were built and operated by private companies, and were initially wooden until the advent of iron and steel bridges. The Market Street Bridge, opened in 1805, was the first permanent bridge across the Schuylkill River. West Philadelphia has many bridges spanning across the Schuylkill River, including three expressways. University City is connected to Center City by five surface roads. Pedestrians and bicycling 37% of Philadelphia workers commute without a car, compare to 33% for Chicago and 45% for San Francisco. According to a UC Berkeley study, 13 percent of Philadelphia households do not own a car. Philadelphia also has recently expanded their network of bike lanes and has implemented a bike sharing network, Indego which debuted on April 23, 2015 with 60 stations and 600 bikes. Underground transit concourse Philadelphia has a underground transit concourse in Center City, which connects the SEPTA Regional Rail lines with local rail and trolley lines. Throughout the entire concourse are underground entrances to adjacent buildings, as well as the "MetroMarket," a group of small shops and eateries near Suburban Station. Within the underground concourse, it is possible to walk between 8th Street & Market and 18th Street & JFK Boulevard, or from City Hall to Locust Street. Trails Philadelphia has several multi-use river trails. A segment of the Schuylkill River Trail passes along the Schuylkill River from Locust Street northward to Valley Forge, near the King of Prussia mall. In Philadelphia, most of the trail runs through Fairmount Park. The trail to Valley Forge totals , and when completed, will total to Hamburg, Pennsylvania. The Wissahickon Trail branches off from the Schuylkill River Trail and runs along the Wissahickon Creek, terminating near Germantown Avenue. The Pennypack Trail runs along the Pennypack Creek, from the Delaware River to Fox Chase Farm. Sections of the Cobbs Creek and Tacony Creek also have trails. Buses SEPTA City buses SEPTA lists 117 bus routes throughout Southeastern Pennsylvania, with most routes being within