Precasting Operations In Full Swing At Sarah Mildred Long Bridge, Kittery, Maine - Portsmouth, New Hampshire
SEGMENTS, SPRING 2016, VOL. 60
The Sarah Mildred Long Bridge Replacement Project is an important regional crossing linking Maine and New Hampshire across the Piscataqua River as part of the US Route 1 Bypass. With a focus on safety, function, economy, and aesthetics, the bridge features concrete segmental spans for vehicles above and heavy rail below. Span lengths for the vehicular bridge include 162', 270', 283', 307', 320’, 2 @ 210', 319', 221', and 132'. The heavy rail bridge below has concrete segmental spans of 102', 3 @ 160', 135', 2 @ 69', 135', 2 @ 160', and 127'. The 56' vertical clearance over the navigational channel provides for passage of almost 70% of the vessels in the typical position. The four towers supporting the lift span, which goes up for 135' clearance and down for trains, are precast concrete segmental hollow sections uniquely shaped to accommodate the internal workings of the lifting mechanisms. The bridge was designed by FIGG/Hardesty & Hanover, Joint Venture, with FIGG accomplishing the segmental bridge spans.
In the fall of 2014, construction began with installation of work trestles in the river which are used to provide access for drilling and pouring the 10' diameter drilled shafts for the vehicular approach bridge, railroad approach bridge and lift tower foundations. For the segmental approach bridges, spread footings and piers are currently being cast-in-place on the New Hampshire side. The drilled shaft footings for river piers will be formed using a precast tub system designed by Cianbro.
Cianbro is precasting structural elements at three different locations:
- Lift tower segments are being precast by Cianbro adjacent to the bridge site at the Port of New Hampshire. This summer, Cianbro will erect the towers to half-height to start work on the mechanical andelectrical rooms.
- Vehicular approach and railroad approach segments are being precast at Unistress in Pittsfield, Massachusetts. Vehicular approach segments that are too tall to be delivered by truck will be delivered by rail.
- All railroad approach segments will be delivered by truck. Precasting of both railroad and vehicular bridge segments will continue into next year, with erection starting in the late summer.
- Drilled shaft foundation tubs are being precast at Coastal Precast in Chesapeake, Virginia, and will be complete this spring. The tower footing tubs are precast in nine segments using the short-line match cast method.
The new bridge will be open to traffic in September 2017.