Crossrail engineers leaving for HS2 is ‘a big risk’ for London project Crossrail chief executive Mark Wild has conceded that there is a "big risk" of specialist engineers leaving the project to work on High Speed 2 (HS2) before the Elizabeth line is open. As Crossrail nears completion and work ramps up on HS2, concerns have been raised about Crossrail’s ability to hang on to specialist engineers needed to complete the job. The London Assembly transport committee will publish a paper on Crossrail later this week. It is expected to raise concerns about staff leaving to work on projects such as HS2.