Con Edison Harlem River Utilidor Tunnel
MRCE designed a power transmission “utilidor” tunnel under the Harlem River, between the Bronx and northern Manhattan, a heavily urbanized environment. An extensive monitoring program was put in place during construction to detect impact on the nearby Broadway Bridge, occupied office buildings, and a commuter railroad 20 feet from the northern shaft. Due to the limited turning radius of the transmission feeders, the transition zone between the shafts and tunnel required complex geometry with a large sloped, overhanging section. MRCE developed an innovative ground support design of the complex portal geometry, using numerical modeling and a detailed understanding of the rock mass. Anticipating difficult ground conditions in the marble bedrock, MRCE developed a probe drilling and pre-grouting program to ensure safe and timely tunnel construction.