I-95/I-91/Route 34 Interchange Reconstruction

The Connecticut Department of Transportation (CTDOT) I-95 New Haven Harbor Crossing (NHHC) Corridor Improvement Program is an extensive transportation improvement initiative intended to increase capacity and improve safety along the I-95 corridor between New Haven and Branford. Located on this section of I-95 is a major interchange with I-91 and Route 34. The reconstruction and reconfiguration of this interchange forms Contract E of the NHHC program.

As the prime engineering consultant for Contract E, Lochner performed complex interchange, roadway, and structural design to reconstruct the high-volume, multilevel I-95/I-91/Route 34 interchange. The design incorporated lanes from the new Pearl Harbor Memorial Bridge and improved the existing connections between the three major routes. To improve the existing configuration, a number of entrance and exit ramps were removed, and new connections were constructed—notably, the I-95 southbound to I-91 northbound connection, which was increased from one to two lanes. Lochner was also responsible for the design of 20 ramp or bridge replacements under the contract. In addition, the portions of I-95 and I-91 within the interchange area were reconstructed to include full shoulders, a new median barrier, drainage, signing, and lighting.

Maintaining the traffic flow throughout the reconstruction of this large, multilevel interchange was a major design challenge. Lochner drew not only on its design expertise but also on its considerable experience in construction engineering to develop comprehensive maintenance-of-traffic and construction staging plans. These plans optimized the construction schedule while maintaining traffic operations between the three high-volume corridors. Construction of the interchange began in 2010 and was completed in late 2016. Over this six-year period, Lochner responded to changing client needs and made numerous additions to the project design plans under expedited time frames so as not delay the overall project schedule. Lochner also placed a full-time senior liaison engineer on site throughout construction as a representative of the design team, which added significant efficiency and responsiveness to the post-design phase of this complex project.

Lochner was also the prime consultant for three related subcontracts. Contract E1 concerned an old harbor site within the interchange area, which was filled with organic material. The compression of this material was a necessary precursor to Contract E construction. Lochner provided design services for soil preloading at the site, including drainage and utility relocations, and oversaw the monitoring of the soil settlement. Contract E1 was completed in 2004.

Contract E2 was located at the southern project limit and linked the new construction to the existing roadway conditions in the Long Wharf area. Under the E2 contract, Lochner designed temporary tie-in facilities, which CTDOT intended to replace at a later date. The plans included a flyover from I-95 northbound to Route 34 westbound; eight new retaining walls; the complete or partial construction of three bridges; the deck replacement and widening of an existing structure; and the demolition, reconstruction, and relocation of several other ramps and bridges within the project bounds. In addition, Lochner’s design increased the I-91 southbound to I-95 southbound connection from one to two lanes.

On completion of the Long Wharf environmental assessment—which investigated the impact of the proposed tie-in facilities—the City of New Haven and CTDOT selected the no-build alternative. The NHHC Program Manager therefore issued a third subcontract, under which Lochner revised and expanded its design plans to provide a permanent design solution between the southern limit of Contract E and a future construction project that was planned for the West River area. Lochner designed a series of alternatives that would increase the capacity of the corridor between I-95 Interchanges 45 and 47 yet minimize impacts to a nearby park and nature preserve. Lochner’s final plans widened I-95 to accommodate an additional auxiliary lane between the two interchanges, which increased the weave distance by 40% between the Long Wharf Drive on-ramp and the Route 34 flyover. Lochner also designed the reconstruction of all structures impacted by the roadway widening, including overhead signs, retaining walls, and the bridge carrying I-95 over the Long Wharf Extension. Lochner coordinated throughout the design with the engineering consultant for the West River project to ensure the compatibility of the new facilities. The construction of the Long Wharf improvements was completed in 2016.