A wall collapse at the north end of the State Route 99 tunnel in Seattle, US has injured four people working at the site.
The men were working on an elevator shaft to install rebar for a concrete wall at the tunnel’s north portal work zone. They fell 25ft when the wall collapsed.
According to reports, none of the men received life-threatening injuries.
A statement from design and build contractor Seattle Tunnel Partners said emergency procedures were followed throughout the incident.
The cause of the collapse is currently under investigation.
The Seattle tunnel project, which will replace the Alaskan Way Viaduct, has been beset with delays, most notably caused by the breakdown of a tunnel boring machine, known as Bertha.
The recent wall collapse occurred about two miles north of the 120ft-deep recovery shaft that has been created to access and repair Bertha.