Around 30 protesters converged on the Leeds Arena construction site on Friday of last week.
The protest was part of the campaign against the victimisation of 48 Crossrail workers over union recognition and health and safety standards.
Electrician Pete Shaw said, “This is just the beginning of the fight to bring the construction companies back into line on union recognition and the strict observance of safety regulations.
“We know where the sites are. This campaign cannot stop until our workmates at Crossrail are reinstated.”
Activists also protested at the Bam construction site at Moorgate, London, and blocked the road during rush hour.