DOVER – With the start of construction on the Dover side of the Spaulding Turnpike widening project, N.H. Department of Transportation officials are planning a public information session in the city to review the scope of the work and introduce the contractor, Severino Construction.

DOT officials also want to discuss four options for the old Gen. Sullivan Bridge that range from wholly rehabilitating the circa 1935 span to replacing the structure. It currently serves as the only pedestrian/bicycle connection over the Piscataqua River and Little Bay between Dover and Newington.

The Gen. Sullivan Bridge closed to motor traffic in 1984 and has been used since by pedestrians and bicyclists. But its condition and safety have deteriorated over the years, prompting transportation officials to review options on how to maintain pedestrian and bicycle access between Dover and Newington.

Cota said an engineering analysis of the bridge prompted four options:

– For $32.7 million, rehabilitate the entire bridge, including replacing rusted trusses and steel, repainting it, and restoring it to its original look;

– For $32.4 million, maintain and restore the center span, but replace the approaches on either side with narrow decking;

– For $31.7 million, keep the piers in Little Bay that hold up the bridge, but replace the entire cement and steel superstructure with something more narrow and smaller – a sort of “Mini Me” version of the current bridge;

– For $44 million, design and build an entirely new bridge that replaces both the piers and the superstructure.

Cota said any options beyond fully restoring the existing bridge will have to gain approval of the Federal Highway Administration and N.H. Historic Preservation Office, a division of the state Division of Historical Resources.

Federal funding that helped build the new Little Bay Bridge for the turnpike widening came with a proviso that the Gen. Sullivan Bridge, which is an historic example of a deck truss bridge, be restored.

A contract – called Contract Q – awarded to Severino is worth $67.1 million. It is one of several contracts that are part of the Route 16 widening project that has a total cost of about $270 million.

“Severino will be seen in this corridor over the next four years,” said the DOT’s Keith Cota, pointing to a completion of the Dover end of the project in October 2020.

“The work you are seeing right know is prep work in advance of the heavy construction that will be completed over the next several years,” he said. “They have several small objectives to complete by end of this year that will not directly affect traffic movements in this corridor.”

Included in the work are the establishment of staging areas, tree clearing operations, construction of erosion control measures and construction of roadway widening and embankments in the Exit 6 area to facilitate construction of the new Route 4 Bridge, and partial soundwall construction. Road work signs have been placed along Route 4 advising motorists of the construction zone ahead.

Recent tree clearing was done with advice from federal wildlife officials relative to the northern long-eared bat, which the U.S. Fish & Wildlife Service deems an endangered species.

There was concern, according to Cota, that trees in the construction zone were being used for roosting by a significant population of the bats. But he said testing by the wildlife service – using sonar equipment – found the numbers “were not to the point where we have to put restrictions in the contract.”

Ultimately, the turnpike will be widened to four lanes in each direction between the new Exit 3 in Newington and what will be a new Exit 6 in Dover over new and rehabilitated bridges over Little Bay. Work on the Newington side of the project was completed last spring. Work on the Gen. Sullivan Bridge as a pedestrian/bicycle path is a companion contract to the widening project.

Besides widening the turnpike, specific work in Contract Q includes:

– A reconfigured Exit 6 interchange that will allow traffic both east and west on Route 4. Currently, only Route 4 west access to Durham is possible;

– A new Route 4 bridge to accommodate the new traffic patterns on the new Exit 6. Cota said the new bridge will be constructed offline just to the south of the existing overpass. Then traffic will be moved to the new bridge to allow demolition of the old overpass. With the new traffic pattern, motorists will be able to get on Route 4 east (Dover Point Road) to Dover, an option not available now;

– A so-called “hybrid” roundabout to replace the traffic lights at the intersection of Route 4, Boston Harbor Road, and Spur Road at the foot of the Scammel Bridge. DOT said repaving of the Scammel Bridge is included in the contract. This is needed, said Cota, to prepare the lanes for the approach to the new roundabout;

– Repaving and new sidewalks for the length of Boston Harbor Road. The current sidewalk ends at the Department of Motor Vehicles. The sidewalk will be extended to beyond Newick’s Restaurant to Hilton Park;

– Soundwalls to dampen traffic noise on the north- and southbound lanes of the turnpike near Pomeroy Cove. The state considered transparent soundwalls to allow a continued view of the cove from the roadway, but Cota said cost factors require cement and timber soundwalls.

“It came down to a cost analysis of an additional $1 million,” he said of the transparent soundwalls.