Construction on New Hampshire Department of Transportation's (NHDOT) massive Spaulding Turnpike Rehabilitation Project in Newington and Dover, New Hampshire, recently passed the seven-year mark, with work on three of the five contracts completed, a fourth contract underway, and a fifth contract under review for possible advertising next year.

Work on a 3.5-mile stretch of the Turnpike, the principal arterial linking the seacoast area and I-95 with Concord via U.S. 4, and with the Lakes Region and White Mountains via N.H. 16, has been underway since 2010.

With a price tag exceeding $250 million, this ambitious 10-year improvements project extends north from the Gosling Road/Pease Boulevard Interchange (Exit 1) in the Town of Newington, across the Little Bay Bridges, to the Dover toll plaza, just north of Exit 6.

NHDOT and consulting engineers broke the project into five separate contracts: 11238L, M, O, Q and S. Four of these contracts are related to preceding and succeeding contracts in an intricate overlapping pattern that involves multiple, complex traffic shifts and construction phases presenting difficult challenges for contractors.

According to NHDOT, the construction is necessary to improve long-term mobility and safety along this section of highway, which has experienced many vehicle crashes over the years. The agency notes that a study of accidents on this section of the Turnpike between January 1997 and December 2003 showed there were well over 1,200 vehicle crashes The Turnpike has closely spaced interchanges, substandard geometry and shoulders, and limited capacity for handling weekday morning and evening commuter travel. Currently, the Turnpike carries more than 70,000 vehicles per day, with 94,000 vehicles per day forecast for 2025. NHDOT says that if the Turnpike were not improved, weekday traffic congestion would spread to additional hours of the morning and evening, and safety conditions would continue to deteriorate.

Key Project Elements

As part of the construction, the existing Little Bay Bridge (LBB) is being widened, and five of the Turnpike's six interchanges in this stretch of roadway are being consolidated or reconfigured. Exit 2 and 5 are eliminated and Exits 3, 4 and 6 will provide full access in all directions. Four lanes of Turnpike are created in each direction (three general purpose and one auxiliary lane) between Exit 3 and Exit 6, while three lanes in each direction are built south of Exit 3 and north of Exit 6.  This compares with two lanes in each direction for the old Turnpike.

The LBB widening encompasses two separate contracts and is the largest and most complex of six bridge jobs included in the project. The existing LBB is actually two side-by-side girder bridges - one for northbound traffic, the other for southbound - that carry U.S. Route 4, N.H. Route 16 and the Spaulding Turnpike across Little Bay at the confluence with the Piscataqua River. The twin bridges each have two travel lanes and share eight foundation piers, but separate hammerhead columns at each pier support the bridge superstructures.

The first bridge was opened in 1966. It supplemented an older bridge across the bay, the General Sullivan Bridge, a riveted, nine-span through-deck truss structure built in 1935.

As traffic continued to increase, a second, 1,600-foot bridge was built alongside the first one in 1984. When the second bridge was opened, NHDOT closed the General Sullivan Bridge to vehicle traffic. The agency plans to have this landmark structure rehabilitated to serve as a recreation facility for pedestrians, cyclists and fishing enthusiasts.

The status of each of the five contracts is presented below:

Contract L (2010-2013)

In spring 2010, Cianbro Contractors of Maine was awarded Contract L. The principal component of this $54.1 million effort was the construction of a new LBB located between the existing nine-span LBB on the east and the General Sullivan Bridge on the west. Eight concrete pier bents support the superstructure of the four-lane addition between the north and south abutments, with each bent comprised of three circular columns built in turn on foundation shafts drilled into bedrock. It was a tight fit, with only a 21-foot space between the foundations of the new bridge and the General Sullivan Bridge to the west, and an even narrower, 14-foot space between the foundations of the new LBB and the existing LBB to the east. Built-up steel plate girders were placed on pier bents to support the deck, which consist of precast/poured-in-place concrete composite topped with bituminous concrete pavement.

Cianbro also built portions of a wider southbound barrel (SB) of Turnpike from the LBB in Dover approximately 800 feet north, stopping just short of the existing Spaulding Turnpike. This contract was completed in the fall of 2013, with SB and NB traffic shifted onto this new bridge in 2015.

Contract M (2012-2015)

Meanwhile, Alvin J. Coleman & Son Inc. of Conway, New Hampshire, started work on Contract M in the spring of 2012. This $47.5 million project constructed the Exit 3 interchange, discontinued Exit 2, built the Spaulding Turnpike from the southern limit of work to the Exit 4 area, and completed the Exit 4 SB ramps and the NB off-ramp.

The Exit 4 NB on-ramp required an interim match to the proposed SB barrel of the Spaulding Turnpike while R.S. Audley rehabilitated the existing LBB in Contract O.  The interim roadway connection of the proposed Spaulding Turnpike in Dover to the existing Spaulding Turnpike occurred in this contract together with the reconstruction of the Exit 5 ramps. These connections allowed the SB and NB barrels to be shifted onto the new LBB that was constructed in Contract L by Cianbro.

Coleman also constructed "wet extended detention ponds" alongside the Exit 3 NB on -ramp. Completing the ponds allowed the contractor to finish all required drainage work. Most of the water in the highway corridor will go through one of these ponds where debris, sediments, and pollutants are collected and filtered out. Coleman completed Contract M in the fall of 2015.

Contract O (2015-2017)       

Contract O, awarded to R.S. Audley of Bow, New Hampshire, for $20.4 million, was launched by the contractor in spring of 2015. Audley rehabilitated the existing LBB while traffic was shifted to the SB barrel of the new LBB by Coleman in Contract M.  Minor roadway approach work along the Spaulding Turnpike was included in Audley's contract. 

Audley's project included installing shielding under the old northbound bridge, removing and replacing the concrete deck, and rehabilitating both abutments A and B (Newington and Dover ends). Existing structural steel on the ends of the bridge was removed in order to rehabilitate the abutments, bridge seats were rehabilitated and repairs were made to the face of existing concrete piers.

In 2016, crews formed and placed a new concrete deck over the four easterly existing structural steel girder lines. This deck then became the work platform for Audley personnel as they set new structural steel (six girders lines) between the existing LBB and the new LBB constructed by Cianbro in Contract L.             

Audley essentially completed its work in the fall of 2017.  Traffic was not shifted onto the completed bridge until Severino Trucking, awarded Contract Q, subsequently finished roadway approach work.

Contract Q (2016-2020)

Severino Trucking Co. Inc. of Candia, New Hampshire, commenced work on its $70.6 million project, Contract Q, in September 2016. Contract Q is one of the most complex projects let by the NHDOT, with staged construction taking place through nine different traffic shifts. This project completes the majority of the Spaulding Turnpike improvements in Dover and opens up all of the Spaulding Turnpike improvements.

Roadway construction involves the widening of the Spaulding Turnpike from the Woodbury Avenue interchange 3.2 miles north to a point 3,000 feet past the Dover Toll Plaza.  It will create eight lanes between Exit 3 and Exit 6 on the Spaulding Turnpike, and will provide the final roadway match to the new Little Bay Bridges (the combined new LBB and existing LBB, which are renamed Southbound Bridge No. 201/024 and Northbound Bridge No. 201/025, respectively).  

Work on this project will also include the reconstruction of the Exit 6 Interchange, including the following items: replacement of the U.S. Route 4 Bridge; the construction of a roundabout at the intersection of Route 4 and Boston Harbor Road, a local road; and improvements to Dover Point Road west, another local road and Boston Harbor Road, and the construction of noise abatement wood panel soundwall from the Little Bay Bridge to a point north of the Dover Toll Plaza.  

Besides widening the Turnpike, Severino will eliminate Exit 5, construct a full access interchange at Exit 6, and remove and replace the existing US Route 4 Bridge over the Turnpike. The Route 4 Bridge footings are supported by high modulus columns constructed by jet grouting to mitigate liquefaction and settlement of insitu soils. This project also entails micro tunneling for new water and sewer lines under the Turnpike. Other work consists of improving Boston Harbor Road and Dover Point Road west.

Work quantities for the project are substantial: 210,00 cubic yards of excavation, 231,000 cubic yards of embankment-in-place, 250,000 cubic yards of select materials, 85,000 tons of pavement, 262,150 square feet of wood panel soundwall, 31,000 linear feet of drainage pipe, 468 drainage structures, two sewer pump stations, 3,700 linear feet of sewer pipe, and 3,000 linear feet of water pipe. Severino is scheduled to complete Contract Q in fall of 2020.

Contract S (2018-2022)       

The last construction contract for the Spaulding Turnpike Improvements Project in the Town of Newington and City of Dover is Contract S for the rehabilitation of the General Sullivan Bridge (GSB), with design currently under review by NHDOT.

Opened in 1934, the GSB was the first span in New Hampshire to be designed as a continuous arched truss, i.e., without structural breaks at its supporting piers. According to NHDOT, GSB is considered one of the most significant historic bridges remaining in New Hampshire as an early example of continuous span bridge design. This iconic bridge is a nine-span steel deck- and thru-truss with an overall length of 1,528 feet, a 32-foot-wide deck, and a substructure consisting of two reinforced concrete abutments and eight concrete piers with granite block facing and caps.

Vehicular travel on the bridge was discontinued in 1984 when the second LLB was opened.  Since then, the GSB has been a bay crossing for bicycles and pedestrians. Bridge engineers recently reported the superstructure (truss, deck, and floor system) to be in critical condition and substructure (piers and abutments) to be in fair condition, based on thorough inspections.  

 The aim of the proposed GSB rehabilitation is to maintain the historic landmark structure to provide pedestrian and bicycle access and allow for fishing use. Work will include removal and replacement of the deck and floor system, replacement of 1930s rivets with high-strength bolts as necessary, and removal of the north embankment and portions of the north abutment.

Special thanks for photos and information provided for this article by NHDOT's Keith Cota, P.E., Chief Project Manager, and the following NHDOT Bridge Design staff: Robert Landry, Robert Juliano, Nickie Hunter, and Denis Switzer.