Project Detail

Penobscot Narrows Bridge & Observatory

Prospect & Verona Island, ME

This bridge is unique to the State of Maine, as it is the only cable-stayed bridge and will become the tallest occupied structure in the State of Maine

Scope of Work

Cianbro constructed a 2,119-foot long, 57-foot wide cable-stayed bridge including twin columns/pylon reaching 440 feet in the air. The Prospect side pylon includes an elevator and observatory area.

Project Details

  • Performed 20,000 cubic yards of structural earth excavation and 2,700 cubic yards of structural rock
  • Drove 288 each HP 14 by 117 H-pile
  • Erected two 60 foot by 70 foot by 17-foot cast-in-place footings including 1,200,000 pounds of reinforcing steel, 2,600 cubic yards of concrete in Pier 1 footing and 3,300 cubic yards of concrete in Pier 2 footing
  • Constructed two cast-in-place lower pylons with #18 rebar, including 1,500,000 pounds of reinforcing steel, and 3,050 cubic yards of 6,000 pound per square inch concrete
  • Constructed two cast-in-place upper pylons including 5,200 cubic yards of 6,000 pound per square inch concrete placed in 15 lifts and 580 tons of #10 rebar 
  • Constructed the mainspan/backspan segments including 14,000 cubic yards of concrete placed in 91 mainspan segments and 90 backspan segments 
  • Installed 40 cable stays ranging from 283 feet to 1,136 feet in length
  • Installed 1,000,000 pounds of transverse and longitudinal post-tensioning: 305,000 pounds of post-tension bars, 250,000 pounds transverse post-tension strand, and 324,000 pounds drape and continuity post-tension strand

Lean, Innovative, and Unique Project Solutions

The cables were strung through the pylons rather than attached to the pylons eliminating attachment stress points. The cable passes through cradles designed to hold the individual strands of the cable in place avoiding strand-to-strand contact with the cable, which could possibly weaken the strands.


American Society of Civil Engineers Outstanding Civil Engineering Achievement Merit Award
ACM Build Maine Award