CARY — A construction worker who was trapped for two hours Tuesday in a collapsed trench remains in critical condition at Duke Medical Center. Cary Fire and Rescue workers were able to save the man by using a newly acquired unit designed specifically for such accidents.

It took just about everything you could imagine for Cary Fire and Rescue to pull Mark Swartwood to safety. The 33-year-old builder was trapped after a 12-foot trench at a housing development site collapsed around him.

Cary's Rescue team responded with a brand new trench rescue unit filled with shoring devices, air braces and more. Cary Fire and Rescue Capt. Gene Pope says, without it, it would have taken hours longer to free Swartwood without that equipment.

Using the new unit, rescuers were able to free Swartwood within two hours and get him to the hospital quickly. The trench has now been filled, but investigators will be focusing on whether it had a proper shoring device, something designed to protect workers in the event of a collapse.

OSHA Director, Bob Andrews says there's a lot at stake.

Andrews says trenches fail because of vibrations from heavy machinery, poor weather conditions such as excessive rain, and a lack of adequate trench bracing. It appears that all those factors could have been factors in Tuesday's collapse.

OSHA won't comment on the specifics of its investigation, but it encourages builders to attend its trenching safety classes. The organization also urges people to call them if they see a trench that looks dangerous.