South Eastern Freeway is a freeway in South Australia (SA). It is a part of the National Highway network linking the state capital cities of Adelaide, SA, and Melbourne, Victoria. It is signed as the M1. It carries traffic over the Adelaide Hills between Adelaide and the River Murray, near Murray Bridge, where it is connected via the Swanport Bridge to the Dukes Highway, which is the main road route to Victoria. It was formerly signposted as Princes Highway, which refers to the coastal route from Adelaide to Sydney via Melbourne. It is often referred to by South Australians simply as the Freeway, as it was the first freeway in South Australia, and is still the longest, and the only one with "Freeway" in its name rather than "Expressway" or "Highway". The South Eastern Freeway includes twin-tube tunnels, the Heysen Tunnels, in the descent towards Adelaide, the first of their kind on the National Highway. Route South Eastern Freeway starts at the intersection with Glen Osmond Road, Cross Road and Portrush Road in Glen Osmond. It heads southeast as a six-lane, dual-carriageway route. It travels across the Adelaide Hills. It goes through a hill, via the Heysen Tunnels. The freeway is a major freight route. It has arrester beds and concrete median barriers, with street lighting between Glen Osmond and Crafers. The freeway narrows to four lanes just before it bypasses Crafers. It continues in a south-easterly direction, past Stirling, Hahndorf and Mount Barker, before narrowing further to a two-lane, single-carriageway. It crosses the Murray River over the Swanport Bridge, and ends just east of the crossing in Long Flat, south-east of Murray Bridge. History Prior to the initial construction of the freeway in the 1960s, inbound and outbound road traffic between Adelaide and south-eastern South Australia or Victoria used a two-lane highway originally built in the early part of the 20th century. With growth in Adelaide's population, issues of congestion and safety mandated reconstruction. Studies began in 1962 for a freeway commencing from Crafers, that endpoint selected arguably due to the massive expenditure required with the precedent upgrade of the Mount Barker Road. Road construction began in 1965 from Crafers. The first stage of eastbound traffic lanes were opened in 1967. The first westbound section opened in 1969. The freeway was opened in stages as construction progressed. The final section bypassing the town of Murray Bridge and connecting to