Two ice-breaking tug boats are hard at work on the Delaware River these days. WPVI

PHILADELPHIA (WPVI) -- The icy weather doesn't just cause trouble for the roads but for the waterways as well.Every day when ice starts forming, the crew of the Coast Guard icebreaker CAPSTAN casts off the lines and head out into the Delaware River - never knowing what they'll find out there."We look forward to the winter every year. This is what the boat is built for, this is what we are out here to do," said US Coast Guard BM1 Matt Bailey.The CAPSTAN is one of two ice breakers working 140 miles of the Delaware River.The ice breaker was built in 1961 and can still handle ice up to 18 inches thick."Usually once it gets above two feet we usually call in a bigger boat, such as a 175 footer, but we can handle everything up to about two feet," said SCBM Christopher Stover, US Coast Guard.On Wednesday, the ice ranged from paper thin to eight inches thick.If the river freezes over, it can bring shipping commerce to a standstill.The big tankers and freighters can handle the ice but smaller vessels like flat fronted barges can easily get stuck.However more important than commerce is safety."What we focus on, first and foremost, is search and rescue and coastal security of all the vessels out on the water, then we look into vessels that are in urgent situations that may need our assistance breaking out of the ice,: said SCBM Stover.A buoy, discovered 165 yards out of position, is an example of a safety issue.That's because the ice grabbed ahold of it and dragged it with the tide.A large ship could have gone aground if CAPSTAN hadn't sent out notice of the wayward buoy.On Wednesday, the CAPSTAN cleared the shipping channel from Philadelphia to Trenton and they'll do it all again on Thursday.