Concrete Encased Steel Beams

A few weeks ago I did a routine inspection of a concrete encased steel beam bridge. The bridge is located in Tiverton RI. The five concrete encased beams span 35.1'. To access the underside of the bridge we used a small boat which halfway through the inspection sprung a leak. The remaining time was spent in waders, which happened to also have leaks. 

The beams exhibit spalling to the encasement along the undersides exposing the steel bottom flanges. The exposed steel bottom flanges have areas of section loss up to 44% of the original thickness. We were able to find the remaining thickness with a D-meter after spending some time cleaning the surface and making it smooth enough the get a reading.

The concrete deck has several spalls in each bay with exposed and severed rebar.

Just upstream from the bridge there is a spillway with a fish ladder. The damned off pond has large schools of fish and it was a crazy site since they were probably farmed fish and were not afraid of people.

Overhead Tunnel Inspection

The Tip O'Neill Tunnel was opened 10 years ago and carries the Central Artery below Boston's downtown area.  The overhead inspection consists of the exhaust plenums, roof slab, utilities and lighting.

The tunnel's ceiling is has fireproofing throughout the underside which makes it difficult to determine the condition. Areas of the ceiling fireproofing have been removed to access utilities and allow inspectors to view the roof slab. The exposed areas of the slab show localized hairline cracks.

The lighting along the top of the walls have been connected with metal clips which are prone to failing and now have six acetal zip ties. The majority of the metal clips are in place with six ties but a few of the lighting structures have loose clips or broken ties causing displacement and cracked lenses. 

To access the tunnel the we piggybacked with MassDOT as they cleaned the tunnel. It was pretty interesting being able to see how the tunnel was cleaned. First the safety walks were cleaned of debris using some sort of leaf blower. Secondly the walls were sprayed with some type of soap solution at a high pressure. Next they were scrubbed. After that the walls were scrubbed by a dozer with a brush attachment. After the brushing a water truck with attached power washer sprayed off the wall. Finally the lanes were cleaned using street sweepers. The entire time the exhaust fans were blowing to help clear out any dust. It's great to see them maintaining the structures since we don't always get to actually witness it.