escalators at Capitol Hill and University of Washington stations experienced several major failures and shutdowns in the two years since the University Link extension was opened. These failures were attributed to the installation of standard commercial escalators instead of stronger escalators designed for transit stations. A new escalator contractor was selected to provide preventative maintenance in lieu of a proposed replacement plan; new stairways and connecting passageways were also opened to allow for alternative access. The Tukwila section of the line was shut down over one weekend in October 2018 for major repairs after cracks were discovered in the rails on the bridge crossing Interstate 5. Renaming and Northgate extension Central Link was renamed to the "Red Line" as part of a systemwide rebranding in September 2019 by Sound Transit to prepare for the arrival of East Link (the Blue Line). Two months later, the agency announced that it would consider a new name after complaints due to the similarity of the "Red Line" with redlining, which historically affected residents of the Rainier Valley. A new designation, the 1Line (colored green), was announced in April 2020 and took effect in September 2021. In January 2020, Sound Transit began a ten-week construction project called "Connect 2020" that required trains to single-track in the Downtown Seattle Transit Tunnel. The closure of tracks for work on the East Link Extension where it meets the existing tracks at International District/Chinatown necessitated the construction of a temporary center platform at Pioneer Square for use by through-riding passengers. Sound Transit deployed four-car trains running every 13–15 minutes and implemented restrictions on carrying bicyclists on trains through downtown. The project was completed in late March after a week-long delay in testing, but the frequency restrictions remained due to the coronavirus pandemic and local shutdowns. Service was reduced to every 30 minutes in April and partially restored in September to every 8 minutes during peak hours and 15 minutes during most other hours. The first of the new "Series 2" light rail vehicles, based on the Siemens S700, entered service in May 2021. The third expansion of the 1Line, a northern extension from University of Washington station to the Northgate neighborhood of Seattle, was funded by the Sound Transit 2 ballot measure in 2008 and began construction in 2012. The tunnel was excavated between July 2014 and September 2016 using two tunnel boring machines, creating a pair of