Филадельфийская Высокоскоростная Линия Норристауна

Interurban rapid transit line in Philadelphia

) is a 13.4 mile (22 km) interurban light rapid transit line operated by SEPTA, running between the 69th Street Transportation Center in Upper Darby and the Norristown Transportation Center in Norristown, Pennsylvania. Originally the Philadelphia and Western Railroad line (which is why the line is referred to by locals as "the P&W"), the line runs entirely on its own right of way. By 2020, the Norristown High Speed Line had an average weekday ridership approaching 11,000 passengers. The Norristown High Speed Line is unique in its combination of transportation technologies. Originally chartered as a Class I (steam) railroad, the line is fully grade separated, collects power from a third rail, and has high level platforms common to rapid transit systems or commuter rail systems such as New York City's Long Island Rail Road and Metro North Railroad, but has onboard fare collection, mostly single car operation, and frequent stops more common to light rail systems. Previously, the Norristown High Speed Line was considered to be a light rail line, according to a 2008 SEPTA budget report; however, the line is currently considered an interurban heavy rail line, according to a 2009 SEPTA business plan, and subsequent capital budgets. It has also been categorized by the American Public Transportation Association as "Intermodal High Speed rapid rail transit". The service is similar in design and use to the Ashmont Mattapan High Speed Line in Boston. The purple color coded line was formerly known simply as Route 100, but was officially changed to its current name in September 2009 as part of a customer service initiative by SEPTA. From 2024, the NHSL is to be rebranded as the M Line. The line has been subject to multiple accidents. The first recorded crash occurred near an Ardmore stop on January 26, 1987 injuring 19. The operator tested positive for drugs and was convicted on reckless endangerment. In August 2017, there was a crash involving an unoccupied railcar at the 69th Street Terminal that injured more than 40 people. As a result, the maximum operating speed on the line was decreased to from .

The Norristown High Speed Line began service in 1907 as the Philadelphia and Western Railroad (P&W), which ran from the present 69th Street Terminal in Upper Darby Township, Pennsylvania to a converted farmhouse station in Strafford, Pennsylvania. In 1911, the line was extended 0.47 mile (1 km) west to a new Strafford P&W station adjacent to the Pennsylvania Railroad's Strafford station, allowing easy interchange between the two lines. In 1912, a 6.2 mile (10 km) branch was constructed from Villanova Junction, 0.33 mile (1 km) west of the existing Villanova station, to Norristown.

From Norristown, the P&W RR connected its tracks with the Lehigh Valley Transit Liberty Bell Route to provide direct electric train service from 69th St. Terminal to Allentown, Pennsylvania. However, in 1951, the Lehigh Valley Transit Company ended its service on the Liberty Bell Route, and in 1953 the company ended all its remaining rail service. Two years later, the P&W RR was taken over by the Philadelphia Suburban Transportation Company (PSTC), which was more popularly known as the Red Arrow Lines. In 1956, the Red Arrow abandoned the original branch between Villanova and Strafford, leaving only electric MU train service between 69th Street and Norristown, as it is today. Part of the Strafford branch right of way has been converted into the Radnor Trail. The PSTC was absorbed into SEPTA in 1970, The bridge, which was built in 1911, had been deteriorating and needed to be rebuilt at a cost upwards of $30 million, though this repair project was budgeted at $7.5 million. The bridge was reopened in November 2013. The remaining $30 million renovation of the entire bridge structure is currently unscheduled. After a period of public comment, SEPTA revised its plans to primarily refer to the line as the "M Line," without number designations.

The fare for a single ride as of January 2020 is $2.50 using cash or $2.00 using the Travel Wallet feature on a SEPTA Key card. Until September 1, 2014, the line used a "pay as you exit" fare collection system on trains towards 69th Street Transportation Center. As part of a general change on several routes approaching 69th Street, passengers now pay onboard upon entering the train. Starting February 22, 2021, fares at 69th Street Transportation Center and Norristown Transportation Center are collected from station turnstiles at all times. The service runs seven days a week from 5 AM to 2 AM. Local trains from 69th Street to Norristown stop at all 22 stations, and the trip lasts approximately 30 minutes. Occasionally, local trains may run only between 69th Street and Bryn Mawr, stopping at ten stations, or 69th Street and Hughes Park, stopping at 18 stations. Before 2019 during weekday peak periods (6:00–9:00 AM, 2:15–6:45 PM), the Norristown High Speed Line featured express and limited services, which stop only at select stations, therefore decreasing travel time between 69th Street and Norristown. Norristown Express service, denoted by red destination signs, travels between 69th Street and Norristown in approximately 22 minutes, stopping at only 16 stations. Norristown Limited service, denoted by blue destination signs, travels between 69th Street and Norristown in approximately 26 minutes and stops at 8 stations. All trains share the same two tracks, so a limited leaving Norristown, for example, will be immediately followed by a local, which stops at more stations, and therefore is spaced farther from the previous train. The next limited will catch up with it. Similarly, a local may leave Bryn Mawr right after an express stops there, and get to 69th Street just before the next express or limited catches up with it. A former Hughes Park Express service, which was denoted by green destination signs, traveled nonstop from 69th Street to Beechwood–Brookline and made all stops from there to Hughes Park in approximately 22 minutes.

Before December 7, 2020, if passengers wanted to board the train at the station, they would have to press a button on the platform, which turns on a light that tells the engineer to stop at the station. The train would only stop if it was scheduled to stop at the station; otherwise, trains did not stop even if the passenger pressed the button. All trains stopped at terminals. After December 7, 2020, if passengers want to board the train at the station they have to be physically visible to the engineer for the train to stop. This is the same as on a light rail or tram/trolley line. In both cases detraining passengers must press a button on board to request the train to stop. LocationMiles (km)StationNotes/ConnectionsWeekdayRidership (2018)Upper Darby0.0 mile (0 km)69th Street T. C. SEPTA Rapid Transit: Market–Frankford Line SEPTA Suburban Trolley: , SEPTA City Bus: SEPTA Suburban Bus: 4,9650.7 mile (1 km)66Haverford1.4 mile (2 km) SEPTA Suburban Bus: 831.9 mile (3 km) 2882.5 mile (4 km)2103.1 mile (5 km) 1403.4 mile (5 km) SEPTA Suburban Bus: 5003.9 mile (6 km) 1164.5 mile (7 km) 145Radnor5.4 mile (9 km) 5625.9 mile (9 km)656.4 mile (10 km)5626.8 mile (11 km) 7.0 mile (11 km) SEPTA Suburban Bus: 3577.9 mile (13 km) SEPTA Suburban Bus: 462Lower Merion8.6 mile (14 km)149.4 mile (15 km) 32Upper Merion10.3 mile (17 km) SEPTA Suburban Bus: 57711.0 mile (18 km)339Bridgeport12.3 mile (20 km) SEPTA Suburban Bus: 31412.8 mile (21 km)106Norristown13.4 mile (22 km)Norristown T. C. SEPTA Regional Rail: SEPTA Suburban Bus: 1,441