Massive recharge basin excavation at Nicolls Road and Route 347 advances reconstruction

A large recharge basin excavation on the northeast corner of Route 347 (Nesconset Highway) and Nicolls Road signals active construction in the current phase of the Route 347 reconstruction, local aerial and on‑the‑ground views show and local reporting on Feb. 23 documented the work. A state DOT spokesperson said, “The work that’s happening now is for the current phase of the Route 347 reconstruction between Hallock Road and Nicolls Road.”

State materials and reporting link the excavation to drainage and stormwater upgrades within a broader corridor modernization plan. “The basin comes as part of a long-anticipated project aimed at modernizing the heavily traveled corridor with new traffic flow patterns, pedestrian and bicycle accommodations, and stormwater upgrades,” project descriptions state, placing the recharge basin squarely in the utility and drainage work needed before lane and intersection changes.

The immediate construction near Lake Grove is part of a nearly $45 million phase aimed at safety and traffic improvements. State highway crews “have started work on a nearly $45 million project near Lake Grove aimed at improving safety and traffic by adding an extra lane and more traffic signals along Route 347,” project documents say. For the Hallock-to-Nicolls segment that now includes the recharge basin, plans call to “add a third lane from Hallock to Nicolls roads on Route 347 to increase the flow of traffic. The speed limit will be reduced to 45 mph and new enhanced traffic signals and crosswalks will be added to one of Long Island’s most dangerous intersections for pedestrians.”

Safety data compiled as part of a regional dangerous-roads analysis underpins the urgency: “From 2014 to 2023, there were 586 crashes at the intersection, including 13 serious-injury crashes and one fatality,” the dataset shows, reinforcing the DOT rationale for signal, lane, and pedestrian-work investments at Nicolls and Route 347.

The long-term centerpiece for the corridor remains a grade-separated interchange at Nicolls Road. “Originally scheduled to start in 2034, the Department of Transportation is now progressing the project to begin construction on the bridge in late 2028 to minimize future construction costs while reducing travel times for motorists,” a state announcement says. State officials describe the project as a “new grade-separated interchange at Nicolls Road, replacing the existing at-grade intersection with a bridge intended to ease congestion and improve safety.” The bridge is expected to begin in 2028, reach completion in 2031, and is estimated to cost between $110 million and $140 million.

This work is the seventh phase of a 15-year effort to modernize 12 miles of Route 347 between Routes 25A and 454, with upcoming phases extending one mile east of Nicolls from Mark Tree Road to Old Town Road and then from Old Town Road to Route 25A, state officials say.

Community and planning advocates note the significance for Long Island’s development patterns. Elissa Kyle, an architect and placemaking director at Vision Long Island, said, “This part of Long Island was developed after building for cars was the norm. This place was farms before it was built for cars,” and called the project “a huge step in the right direction,” adding, “We need to see more of this on Long Island that offers more alternatives and safer ways to get around that don’t require people using cars.” She also described the work as, “a bit nerve-wracking and challenging,” reflecting local disruption as construction progresses.

Several technical details remain unreported in public materials: the exact dimensions of the recharge basin documented on Feb. 23, contractor identities and procurement terms, funding breakdowns for the nearly $45 million and the $110–$140 million bridge estimate, and the environmental permits tied to the stormwater work. With bridge work now accelerated to a late-2028 start and completion targeted for 2031, the excavation at Nicolls and Route 347 is the visible first step toward a multi-phase reconstruction intended to improve traffic flow and pedestrian safety along this critical Suffolk County corridor.