a curved route paralleling the Pan-Philippine Highway (Maharlika Highway) from Calamba to Santo Tomas, Batangas. The expressway then curves as it enters Santo Tomas before it ends at kilometer 57.5, continuing towards Batangas City as the STAR Tollway. History Planning and construction The South Luzon Expressway was originally built during the late 1960s as the Manila South Diversion Road, South Superhighway, or Manila South Expressway as newer roads used to travel from and to Manila. Located then in the province of Rizal, the original stretch of the expressway, spanning approximately from EDSA (Highway 54) in Magallanes, Makati to Alabang Exit in Muntinlupa, was constructed beginning in 1967 and was completed on December 16, 1969. It is the second roadway project completed by the Philippine National Construction Corporation, after North Luzon Expressway. In the late 1970s, the expressway was extended by another from Alabang up to Calamba, Laguna through the Manila South Expressway Extension project. It included the Alabang Viaduct, which crosses over Alabang. In 1982, South Superhighway from Magallanes to Calamba was renamed to Dr. Jose P. Rizal Highway, after the Philippine national hero Dr. José Rizal, by virtue of Batas Pambansa Blg. 264. In 1989, it was renamed to President Sergio Osmeña Sr. Highway, after the Commonwealth President Sergio Osmeña, by virtue of Republic Act No. 6760. The act was amended through Republic Act No. 7625 in 1992 to rename its portion from kilometer 28.387 in San Pedro, Laguna, southwards to Dr. Jose P. Rizal Highway. In 1995, the rehabilitation of the portion of SLEX from Magallanes to Alabang began as part of South Metro Manila Skyway Project Stage 1 that also includes the construction of the elevated Skyway above it up to Bicutan area. Thus, the Alabang Exit, which was also the expressway's former southern terminus, was designated as the concession boundary as PNCC decided to split SLEX into two concessions – the section from Magallanes to Alabang is made part of the Skyway System as the Skyway At-Grade, while the remaining section from Alabang southwards retains the South Luzon Expressway concession branding. Expansion and rehabilitation Rehabilitation work on SLEX started in May 2006, with heavy traffic brought by construction work. Prior to its rehabilitation, the South Luzon Expressway section from Alabang to Calamba was mostly an expressway with a grass median and two lanes per direction. The Alabang Viaduct was widened from three to four lanes per