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, in partnership with Reed & Reed, Inc., constructed a 2,119 ft long, 57 ft wide cable stayed bridge including twin columns/pylon reaching 440 ft in the air where the Prospect side pylon includes an elevator and observatory area.

Project Details

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


2007 American Society of Civil Engineers Outstanding Civil Engineering Achievement Merit Award
2007 ACM Build Maine Award