Due to overhead wire, track and station improvement projects, Southeastern Pennsylvania Transportation Authority (SEPTA) Trolley Routes 10, 11, 13, 34 and 36 will not operate in the Center City tunnel from 10 p.m. on Friday, August 1, through 4 a.m. on Monday, August 18. During the closure, SEPTA's in-house Engineering, Maintenance & Construction Division crews will work around-the-clock on key maintenance and construction tasks to improve safety and service reliability. Members of SEPTA's Track Department will work inside the tunnel, as well as outside at the 40th Street Portal. Crews will weld together long rail strings and install more than 14,000 feet of new rail on the eastbound track of the tunnel from the Portal to 22nd Street Station. At the Portal, crews will also replace two concrete-embedded track switches. This work will include demolishing existing concrete surface track and steel, constructing new track switches and pouring the new concrete surface. SEPTA's Power Department will replace nearly 24,000 feet of worn overhead contact wire throughout the tunnel and almost 5,000 feet of wire support assemblies and protection board on the westbound side of the tunnel between 19th and 30th Street Stations. "This blitz concept is used in the transportation industry because it allows organizations to maximize productivity during improvements projects while minimizing the period of inconvenience to passengers and communities we serve. This is especially true when there is a single track operation, like our trolley tunnel," said SEPTA Deputy General Manager Jeff Knueppel. "Because the Center City tunnel is used 24 hours a day and is a five-mile, single track operation, it is difficult for our crews to get productive work windows. Without this blitz and 17-day closure, we'd have months of nighttime and weekend shutdowns to complete all of the projects." Other work that will be completed during the trolley closure includes replacing worn track components and cleaning the track drains and stormwater system throughout the tunnel; completing maintenance work on the tunnel's signal system and on key components near 34th and Ludlow, where the Route 10 separates from Routes 11, 13, 34 and 36; testing back-up and emergency lighting cables and making numerous station repairs and improvements such as on stairs, lighting and platforms.