a modern trolley car). Four cars are anticipated for service on this line. No funding sources were identified. No further action on this proposal has taken place since the October 2012 release of the study. Proposed airport extension One of the biggest gaps in the San Diego Trolley system is the lack of a connection to the San Diego International Airport. The MTS says the extension presents engineering challenges and would be costly, but the agency's polls and outreach show the extension is one of the most desired projects among the public. Over the years there have been several proposals, with the most serious coming as part of the proposed "Elevate SD 2020" transit tax. That project would have created a new line that connected the airport to both the 12th & Imperial Transit Center and the Old Town Transit Center with a wye spur between the Middletown and Little Italy stations. In April 2020, MTS decided not to pursue the transit tax ballot initiative. However, an extension of the trolley to the airport is included as an alternative proposal as part of SANDAG's Central Mobility Hub project for the airport, which is in the Draft Environmental Impact Report phase . Connecting service between The Trolley and the airport is provided by local bus Route 992 that serves the Santa Fe Depot/America Plaza transit area. A secondary service is the airport's rental car shuttle, which has a stop on its route between the terminal and the rental car center that is a block from the Middletown trolley station. Proposed Purple Line The Purple Line is a proposed San Diego Trolley line that would run from San Ysidro Transit Center at the United States–Mexico border to Kearny Mesa with a possible extension to Carmel Valley. It would run along, or close to I-805 and I-15. In April 2011, the San Diego Association of Governments (SANDAG) released a draft of its 2050 Regional Transportation Plan, which was approved by the SANDAG Board of Directors on October 28, 2011. An inland Trolley line from San Ysidro to Kearny Mesa, though not yet called the Purple Line, was included in the plan. In 2016, SANDAG had a measure on the ballot to fund development of the Purple Line. It failed to pass. In April 2019, the MTS again included the Purple Line in a final version of a November ballot initiative to increase the