NH Rt. 12A bridge over the Sugar River is scheduled to begin rehabilitation in 2023.
Claremont, N.H., residents recently identified traffic impact and safety as primary concerns about the state's plan to rehabilitate the NH Rt. 12A bridge over the Sugar River, which is scheduled to begin construction in 2023.
Officials with the New Hampshire Department of Transportation (NHDOT) met with residents on Nov. 16 to discuss the state's upcoming bridge overhaul on Jarvis Hill Road, a section of NH 12A.
The $3.3 million project, targeted in New Hampshire's current 10-year plan for transportation infrastructure maintenance, aims to remove the bridge from the state's "red list," a lineup of bridges that require interim inspections due to their poor condition.
Originally constructed in 1967, the two-lane steel structure is 276 ft. in length and was last rehabilitated in 1991. Its girders are "heavily rusted in spots" and concrete beneath the bridge deck is crumbling, according to NHDOT Project Engineer Anthony Weatherbee.
He told the Eagle Times that the proposed work will replace the deck, girders and other steel components as well as install countermeasures to protect the piers from the elements during flooding or other high-water events.
The Claremont newspaper reported that the biggest anticipated challenges during construction may be controlling and minimizing the impact on traffic.
For logistical reasons, Claremont officials, including the city council and a traffic advisory committee, want to keep the bridge open during the rehab, according to Weatherbee. To achieve this, the bridge must be converted to a one-lane, two-way bridge during active construction, with traffic signals installed at each end of the span to control the northbound and southbound traffic flow. Crews will work on one side of the bridge while cars and trucks travel on the other.
But NHDOT acknowledged that the bridge's physical location also poses noticeable challenges in terms of safety.
Its north end is less than 100 ft. from the busy intersection of Route 12 and Route 12A, which brings a steady flow of traffic to and from Vermont, as well as vehicles from the Upper Connecticut River Valley and Claremont's manufacturing district.
Street lighting in and around the bridge also is nonexistent, according to the Eagle Times.
"Whenever we have this kind of temporary traffic control setup, my biggest concern is frankly the middle of the night, when everything is quiet," said Teresa Sandell, a project consultant from Missouri-based TranSystems Corp. "So, we want to make sure that we are being as obvious as possible [in our signage and lane designs] in which direction is allotted at that given time."
Traffic Congestion a Concern During Rehab
NHDOT engineers also want to avoid unsafe backups around the intersection. While bridge traffic is often lighter in comparison to the traffic on nearby NH 12, both roads see heavier usage during morning and evening commutes, as well as heavy usage from commercial trucks and agricultural vehicles.
Without proper traffic modifications, the short distance between the bridge's north end and the intersection could potentially create a backup into the intersection of vehicles waiting to cross the bridge.
"So, the traffic signal at the NH 12 intersection will have to be coordinated with the [temporary] traffic signals at the bridge," said Weatherbee at the November public gathering. "They are all going to work together to try to alleviate some of the traffic concerns."
In addition, the project team plans to create two dedicated turn lanes on NH 12, one for left-turns and one for right-turns, "so vehicles wanting to make that turn onto the bridge won't hold up through-traffic or traffic coming from the other direction," Weatherbee noted.
Sandell said that while analysis has shown that some traffic backup occurs during peak hours at the intersection, those backups usually last less than a minute.
"A lot of the management will come down to adjusting the traffic signal times," she added. "We don't expect to see major delays or backups."
The state transportation agency noted that it is still working out the dimensions it could accommodate for wider vehicles to cross the river, such as agricultural equipment, during the bridge's rehabilitation.
Claremont, NHDOT Must Agree on Lane Closures
City leaders, in their meeting with project engineers, preferred keeping the bridge open to two-directional traffic to the alternatives provided by the state, the Claremont news source reported.
Other options included fully closing the bridge — which would have shortened the project length to a single construction season — or limiting the river bridge's use to only one direction of traffic, Weatherbee said. But both alternatives would have required detouring traffic, including commercial trucks and large vehicles through the center of Claremont, which the city is currently working hard to limit.
Preferable detours were rejected because of clearance issues or laws that require New Hampshire to only create detours on state-owned roads.
The bridge rehab is scheduled to begin construction in 2023 and take two construction seasons. Weatherbee said the unforeseen delays, such as material shortages or contractor scheduling, could push the start of construction to 2024.
To keep the bridge open during construction, it must be converted to a one-lane, two-way bridge during active construction, with traffic signals installed at each end of the span to control the northbound and southbound traffic flow.
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