the Alice Springs–Birdum road to Darwin. During the wet season, the road north of Birdum was impassable, which meant that a single railway line was the only connection through to Darwin. Construction was underway by October 1941, once again at a fast pace in an attempt to finish before the next wet season. The road was nearing completion in July 1942, although some sections were yet to be bitumenised. Speed limits There was no absolute speed limit in the Northern Territory before 1 January 2007 but maximum speed limits are now posted throughout the Stuart Highway. Previously, drivers were simply required to drive at a safe speed to suit the conditions. Thus, the Northern Territory section of the Stuart Highway had no speed limits at all. The Northern Territory traffic laws were updated from 1 January 2007 to be similar to the rest of Australia. This included placing a speed limit on all roads ( on major highways such as the Stuart Highway) and significantly increasing penalties for speeding. The South Australian section is signposted as outside built-up regions, between Port Augusta and the Northern Territory border. In October 2013 the NT Government announced a trial period of reverting to an open speed limit on the stretch between Alice Springs and Barrow Creek, beginning 1 February 2014. In September 2015, following the conclusion of the trial, a stretch of the highway had its speed limits derestricted. However, speed limits were restored to this stretch in November 2016; the highest is . In March 2021, the road was closed due to a serious accident 500 km north of Adelaide at Wirraminna where the road collapsed due to burning diesel fuel that melted the road's plastic culverts. Plastic culverts had been used in place of concrete as they were seen as the best material for this particular location as the flood plain of the river is acidic and can destroy concrete culverts. The road was closed while repair works took place. The asphalt also had to be given time to cure and the section of road underwent testing with a road train. With this now complete, both lanes are reopened with speed restrictions in place. Traffic signage is now in place and road users are asked to take extra care while travelling through this section of road. Junctions Motor racing Motor races have been proposed or undertaken on the highway since the