The main beam team, which was refurbished at Robbins’ manufacturing facility in Solon, Ohio, achieved the substantial completion of the factory acceptance test in October. The machine, rebuilt in partnership with contractor Kiewit, will excavate the 1.5km-long Ellicott City North Tunnel, a critical flood mitigation project in Howard County, Maryland.
Robbins says the 5.6m-diameter TBM has a distinguished global track record. It has excavated tunnels totalling more than 18km and is now entering its next chapter as part of Maryland’s largest stormwater infrastructure project to date.
“Robbins and Kiewit share a long-standing partnership focused on quality TBM rebuilds and performance,” said Robbins vice-president Doug Harding. “We are marking not only the acceptance of the machine, but also a continued commitment to delivering durable tunnelling solutions that meet the evolving demands of major infrastructure projects.”
The Ellicott City North Tunnel is central to Howard County’s Ellicott City Safe and Sound plan. Designed to divert stormwater run-off away from the historic downtown – an area hit by multiple catastrophic floods in recent years – the tunnel will convey up to 26,000 gallons (98,000 litres) of water per second during major storm events.
The TBM will bore through a mix of granitic rock beneath Ellicott City.
Kiewit area manager Christof Metzger said Robbins and Kiewit had worked together over the past year to achieve “this milestone of substantial completion of the FAT”.
“Synergy efforts were required and well delivered to get the TBM to increased technical and safety standards,” he said.
Excavation is expected to start in the coming months following TBM assembly and launch shaft construction in Maryland. The TBM’s performance will be supported by Robbins’ field service team to ensure smooth operations throughout the project’s duration.
