Tunnel boring machine (TBM) 1 Elizabeth is underground again after a brief ‘pit stop' while passing through Norwest. On 21 January the first mega tunnel boring machine reached a historic milestone when she broke through into the future Norwest Station area.When Elizabeth first emerged after the 2.1 kilometre journey from Bella Vista she was dirty and had a few bumps and bruises but her overall condition was good. Over the previous four months the 900-tonne tunneller had excavated more than 206,000 tonnes of crushed sandstone and shale and installed more than 7,300 concrete segments to line the new rail tunnel.As she moved slowly through the Norwest Station area Elizabeth was ‘pampered' by maintenance crews who attended to her every need. They especially focused on the cutter head which had chewed through all that rock. Thirty single cutters were replaced and five twin-disc cutters, as well as the bucket lifts which remove the spoil and dump it onto the conveyor system. After being prepared for the next leg of her underground assignment, Elizabeth's massive cutter head began revolving again in early March and she pushed forward into the sandstone and shale between Norwest and Showground.