direction with the viaduct's rehabilitation was completed in November 11, 2008, and the construction of Skyway Stage 2 from 2009 to 2011 caused traffic disruptions on the Bicutan–Alabang section (though mitigated by the use of the sosrobahu method to build and position the bridge piers). Rehabilitation work was finished in June 2009, expanding the Alabang–Santa Rosa section to eight lanes (four lanes per direction) and the Santa Rosa–Calamba section to six lanes (three lanes per direction). One year and six months after the Alabang Viaduct was rehabilitated and widened and eleven months after the completion of rehabilitation and modernization of the expressway's Alabang–Calamba section, the operation and maintenance of the expressway was transferred from the government-owned Philippine National Construction Corporation (PNCC) to South Luzon Tollways Corporation (SLTC) and Manila Toll Expressway Systems (MATES) on May 2, 2010. An extension of the expressway from Calamba to Santo Tomas was constructed from 2007 to June 2010 and opened on December 15, 2010, with the name Alabang–Calamba–Santo Tomas Expressway (ACTEX) and eventually connecting South Luzon Expressway to the STAR Tollway. To decongest traffic, the SLEX Elevated Extension project, originally known as Skyway Extension project, was constructed along the shoulder of the expressway in Muntinlupa from 2019 to 2021 and has connected the expressway's segment south of the Alabang Viaduct to Skyway Stage 2. Future Toll Road 4 The South Luzon Expressway Toll Road 4, also referred to as Toll Road 4 (TR4), is a extension of South Luzon Expressway from Calamba (near its boundary with Santo Tomas, Batangas) to Lucena. Construction will be divided into five segments, with one additional extension to Mayao in Lucena on the revised project outline. The extension project is implemented by the Toll Regulatory Board and will be operated by the SMC SLEX, Inc. (formerly South Luzon Tollway Corporation). The extension would decongest the existing national road between Santo Tomas and Lucena, and provide a modern alternate route for travellers from Quezon to the Bicol Region. Right of way has been acquired for the first three segments between Santo Tomas and Tiaong, and ongoing for the remainder between Tiaong, Candelaria, and Tayabas. Right of way acquisition is ongoing as of 2019, and the groundbreaking ceremony was held on March 26, 2019, alongside the beginning of construction. The future expressway will start near the Ayala Greenfield Estate toll plaza in Calamba rather than in Santo Tomas after various project