Workers for ATC, a joint venture between Alstom, TSO and Costain, reportedly have to walk long distances to go to the toilet as there are no portable toilets at a tunnelling site.
ATC has been contracted by Crossrail to fit out and commission tunnels underneath the streets of London, between Royal Oak, Pudding Mill Lane and Plumstead Portals in the west, east and south east of the city.
Barckley Sumner, head of press at construction union UCATT, told IOSH Magazine: "Our understanding is that working conditions aren't nearly as good as they should be on such a high-profile project."
A spokesperson from Crossrail said: "There are concerns around workers walking a long way to go to the toilet [-¦] We have asked the contractor ATC to investigate these issues."
One worker told Construction Enquirer: "We haven't had a mobile toilet in the tunnel down here for weeks now. We have to walk all the way to Tottenham Court Road which is two miles away."
IOSH Magazine contacted Alstom, which is leading the joint venture, but a spokesperson declined to comment.
The demonstration will start shortly before 7am at the Fisher Street site entrance in Holborn and is expected to last approximately one hour.