The Princes Motorway is a predominantly dual carriage untolled motorway that links Sydney to Wollongong and further south through the Illawarra region to . Part of the Australian Highway 1 network, the motorway is designated with the route number M1. The motorway is sometimes known by its previous signposting F6 (Freeway Route 6) and its previous name, the Southern Freeway, which applied to the sections between Waterfall and Bulli Tops as well as Gwynneville and Yallah. The section between Bulli Tops and Gwynneville was known as Mount Ousley Road, and was first built as a defence route and later upgraded to dual carriageway standards. In early 2013, as part of the New South Wales alphanumeric route conversion process, the entire motorway was renamed to its current name and signposted M1. It is the backbone of road traffic in the Illawarra. As Wollongong and Port Kembla are important industrial centres, freight traffic is heavy. Despite the current decline of the local steel industry, emergence of Wollongong as a commuter city of Sydney has kept the motorway busy. Sections In the north, the Princes Motorway route starts at Waterfall, taking more or less a parallel route with Princes Highway until the sprawling Bulli Tops interchange (with Appin Road (B69) and Princes Highway). There it continues downhill, avoiding the steep Bulli Pass, and bypasses Wollongong CBD, through Gwynneville and continues for , bypassing the suburbs of Yallah and Albion Park Rail, reaching the Albion Park interchange (with Illawarra Highway (Terry Street) (A48)) before connecting with the existing Princes Highway (A1) at the Oak Flats interchange. The motorway can be divided into four sections: between Waterfall and Bulli Tops (formerly Southern Freeway) between Bulli Tops and Gwynneville (also known as Mount Ousley Road) between Gwynneville to Yallah (formerly Southern Freeway) Albion Park Rail Bypass Waterfall to Bulli Tops section Construction of the section between Waterfall and Bulli Tops commenced in July 1970. At 22.9km, it was then the longest section of freeway to completed at one time, at a cost of $30.5 million. Financed by State Government bonds, from its opening on 24 July 1975, this section of freeway initially incurred a toll. This part of the freeway did not feature the Helensburgh Interchange (which subsequently opened in February 2000). The toll operated for 20 years, which was 10 years short of its intended operating length. The main reason for this was local residents