The first part of the North Coast line was built between Casino and Grafton in 1905, as an extension of a line from Murwillumbah. It was extended from Casino to Kyogle in 1910 and South Brisbane in 1930. The section from Maitland junction to South Grafton was opened progressively between 1911 and 1915. The Clarence River at Grafton was the most difficult river to cross, and was the last section to be opened in 1932, upon completion of the Grafton Bridge. A number of private lines were built to connect the South Maitland coalfields (discovered in 1886) with the Great Northern Railway at East Greta Junction near Maitland. By 1918 most of these had been merged into the South Maitland Railway. A narrow gauge railway was built by South Australian Railways from Port Pirie to Broken Hill, in 1888 to serve its silver and lead mine, which was becoming the largest and richest of its kind in the world. Since the New South Wales Government would not allow the South Australia Railways to cross the border, the last was built by a private company as a tramway, the Silverton Tramway from Cockburn to Broken Hill. In 1970 the line was replaced by a standard gauge South Australia government line, completing the standard transcontinental gauge line from Sydney to Perth. The Bryon Bay Train is passenger service in Byron Bay using a 620 class railcar converted for solar operation. Sydney's Dulwich Hill Line, also known as the Inner West Light Rail, runs in the city's Inner Western suburbs from Central to Dulwich Hill. Services on the line are operated by Transdev Sydney. A number of other private railways have been built in New South Wales to serve coal mines, steel works, notably the Port Kembla steel works, formerly operated by BHP (now BlueScope) and quarries, especially in the first half of the 20th century. Because parts of New South Wales are closer to adjacent states than the state owned railway, foreign lines of different gauges have extended short distances into New South Wales. These include:  The Deniliquin line was the first gauge line to be extended into the state. Permission was granted to the Deniliquin and Moama Railway Company by the New South Wales Government in 1874 to construct a line long line from Moama to Deniliquin, connecting with the Victorian Railways system at the Murray Bridge, near Echuca and the line was opened in 1876. This was followed in 1906 when an agreement was made between both states for the Victorian Railways Goulburn Valley line to be extended north into Tocumwal.