Route 156 was commissioned in 1932 as a 14.66-mile east-west route from Old Lyme to Waterford. The north-south segment of today's Route 156, between Route 82 and US 1, was originally numbered Route 86. In 1948, Route 156 annexed that portion and gained its ungainly shape.

Traffic engineers have paid the shoreline segment of Route 156 a considerable amount of attention over the years. Though US 1, and more recently I-95, have always handled non-local traffic, Route 156 has struggled with town, tourist and even marine traffic.

Relocations in Old Lyme

Old Shore Road, near the southernmost point of Route 156, is an old alignment that was bypassed in 1947. In 1955, the easternmost block became SR 578; in 1962, SR 578 was turned over to the town.

Traveling northwesterly into downtown Old Lyme, Route 156 originally followed McCurdy Rd. and Ferry Rd. to Neck Rd. The section of Shore Rd to the west is newer. In Feb. 1959, town residents voted 2-1 to approve the state plan for shifting Route 156 there. The new segment of Route 156, a 1.3-mile limited-access two-lane road, was completed in 1961.

The old Route 156 was retained in the state highway system as SR 528 for a year or so, and then turned over to the town on July 30, 1962.

Non-access designation

The 1973 Draft EIS for a new Niantic River bridge noted:

This term is new to me. My guess is not that there were freeway plans for Route 156; but instead, as sections were upgraded, the state reserved the right to declare them access controlled.

Improvements in Niantic

The town of Niantic and the Niantic River have been perennial chokepoints along Route 156. The original Niantic River Drawbridge, a low-clearance bridge built in 1922 (a draft EIS from 1973 says 1919), was being opened about 6,000 times a year by the 1960s, causing severe traffic backups.

In 1963, the state General Assembly directed the Highway Department to study improving or replacing the bridge. In 1965, it was determined that nearby segments of Route 156 also needed upgrading, and the Department approved a limited-access designation along the route from Old Lyme to Waterford. (This would generally limit access to newly constructed segments of Route 156 to major cross streets.) In 1966, Waterford First Selectman Hugh MacKenzie called for a relocated Route 156 from the bridge to the New London city line.

In 1967, the General Assembly called for a wider study. In 1968, the state released its findings for both the bridge and the highway.

Four alternatives for the bridge were explored.

• A higher drawbridge at same location, with a 35 foot clearance. This bridge would need to be opened only 500 times a year, instead of 6,000 times. However, the embankments needed for the bridge approaches would displace nearly all the developed properties between the bridge and Millstone Road in Waterford.
• A tunnel, 52 feet wide (four lanes), providing 15 foot depth of channel. It would be located about 150 feet north of the existing bridge. The cost would range from $20 million (for a 2,500 foot tunnel) to $28 million (for 3,500 feet).
• Fixed high-level bridge, 52 feet wide (four lanes), with sidewalks. Engineers determined that a 65-foot clearance would allow all marine traffic currently using the river; a 30-foot clearance would prevent over 20% of current traffic; but a 45-foot clearance, allowing all but 2% of traffic, would be an acceptable compromise. Cost was estimated at $2.6 million.
• New movable bridge at new location, with a clearance of 30 feet. This would be more expensive to build than the fixed bridge, and have higher recurring costs.

The higher fixed bridge was the preferred alternative.

The report also discussed three alternatives for relocating Route 156 east and west of the bridge. New sections would be limited access roads, generally two lanes, 40 feet wide.

• A: The new Route 156 would veer southeast at Roxbury Road, and transition to an alignment along the railroad. In downtown Niantic, it would rejoin present-day Route 156. East of the river, it would follow the railroad again to end at US 1 and Clark Lane.
• B: This alternative strayed from Route 156 in the same areas that Alternative A did, but would stay closer to Route 156 than the railroad.
• C: This alternative would bypass Niantic entirely to the north, crossing the river near Daniels Road, and returning to Route 156 near Spithead (with a "P") Road in Waterford.

Alternative B was preferred in the report. The cost in 1969 was estimated at $13 million.

Route 156 was never relocated here. In 1969, town officials were concerned about local impacts, and the state was considered "lukewarm" on the topic. At some point, the state moved to encourage motorists to use other routes by posting a Route B detour, using Niantic River Road, US 1, and Route 161.

Studies and hearings for a new bridge continued.

In July 1973, a draft Environmental Impact Statement by the DOT proposed a fixed bridge, height 55 feet, with 1.8 miles of 2-lane controlled access roadway along Route 156.

In 1975, funding problems led the state to put aside plans for a high, fixed bridge in favor of a smaller, moveable bridge.

A new bridge was constructed in 1991 just south of the old one. It's higher and appears to be fixed, but clearance data is not available. As of the late 1990s, the "Route B" detour is still signed.

Proposed relocation near eastern end

In 2002, there was talk of relocating a small section of Route 156 near its eastern intersection with US 1 in Waterford. A proposed community campus, to open in 2004, would have included land and buildings on both sides of Route 156 in the area: a high school, senior services, sports fields and a preschool. To make it easier and safer to walk there, planners were looking at restricting vehicle traffic, or providing pedestrian overpasses.

One option: "end Route 156 at the intersection with Avery Lane" (across from Route 213), and presumably route it north to US 1.

The first public brainstorming session was held in July 2002. Town First Selectman Paul B. Eccard noted that there is state precedent for moving state highways to accommodate community needs: US 1 in Fairfield and Greenwich; and unspecified highways in Storrs, Newington, and Willimantic.

In November 2002, a traffic consultant favored a $900,000 plan that would redirect Route 156 to meet US 1 at Wild Rose Avenue. A short segment of US 1, from Wild Rose to Vivian Street, would be widened to four lanes.