The R&D Tunnel, or Boring Test Tunnel is a 1.14 miles (1.83 km) tunnel in Hawthorne, California for testing hyperloop and "loop-based transportation". It was completed by The Boring Company in late 2018. The single-bore tunnel was constructed during 2017 and 2018 using a 14-foot (4.2 m) diameter tunnel boring machine, giving a finished 12-foot (3.8 m) internal diameter.