The project followed a two-step design-build procurement, including a qualifications phase followed by a proposal phase. Teams were evaluated based on the best value between technical proposal and price. The owner, Metropolitan Transit Authority (MTA), directly employed the contractor to execute both design and construction.

A key advantage of this model was the ability to develop and submit ATCs during the bid phase. These concepts focused on reducing excavation, improving constructability, minimizing impacts on rail operations, and lowering schedule and cost risk. Because design and construction were integrated under a single contract, these ideas could be evaluated early and incorporated directly into the final design.

The design-build model was also reflected in the organizational structure. MTA retained separate consultants for design and construction management oversight, while the contractor held the design team under the design-build contract. This configuration enabled direct collaboration in advancing ATCs from proposal through implementation.

The Eastbound Reroute is part of the East Side Access program. Its purpose was to reconfigure Harold Interlocking by shifting and realigning the main line tracks to remove at-grade conflicts between Long Island Rail Road and Amtrak trains. The new alignment enables eastbound Amtrak trains entering Harold Interlocking to be routed into the Hell Gate Line on Track 2, decreasing the number of conflicts and allowing Amtrak to increase service.

One of the most significant ATCs advanced during procurement involved the tunnel profile. The preliminary design showed a deeper structure to pass beneath two Long Island Rail Road tracks crossing at a skew. Under design-build, the team evaluated whether that depth could be reduced without compromising clearance or safety.

By reviewing vehicle envelopes for both Long Island Rail Road and Amtrak equipment, assessing life-safety requirements, and analyzing structural thicknesses, the team determined the profile could be raised.

Raising the profile reduced excavation, limited work below the groundwater table allowed shallower approach walls and resulted in a more economical structure. The ability to evaluate and implement this ATC before construction began demonstrates how design-build allows engineering decisions to directly influence cost and schedule outcomes.

Underpinning Honeywell Street Bridge was another area where ATCs were evaluated. Several approaches were studied, including drilled shafts with temporary jacking and micropile-supported systems.

Under design-build, these options were compared for structural performance, constructability, and outage impacts. The selected approach combined supportive excavation with permanent support using hand-dug button piers. These piers were constructed in sequence while the bridge remained supported on its original foundations.

The tunnel roof slab was constructed with openings to accommodate the existing piers. After completion, bridge loads were transferred to the new structure, and the original foundations were removed. This approach improved construction phasing and reduced risk in an area with extremely tight tolerances, reflecting the practical advantages of evaluating ATCs within a design-build framework.

The project included six rail system design packages covering track, catenary, signals, communications, and 750V DC traction and facility power. The diamond crossover installation and long-term outage for the eastward pass and line 3 enabled construction of the box structure and placement of the Reroute track into service.

Under design-build, systems design was coordinated directly with construction sequencing, and ATCs were advanced to improve constructability. This enabled:

• Light detection and ranging (LiDAR) scanning to confirm coring locations into existing manholes.
• Casting conduits into the structure before communications hut installation.
• Aligning catenary sectionalizing with outage windows.
• Developing installation details tailored to field conditions.

Direct coordination between design and construction reduced rework and allowed systems integration within a highly constrained operating environment.

The Eastbound Reroute increased reliability, reduced delays, and added operational flexibility at Harold Interlocking.

Through design-build delivery, ATCs were practical tools used to reduce excavation, improve constructability, and manage project delivery schedules. Integration of design and construction enabled real-time coordination across structural and rail systems in one of the nation’s most complex rail operating environments.

By removing at-grade conflicts at Harold Interlocking, the project unlocked the full potential of the East Side Access program and demonstrated how design-build and ATCs can transform complex rail infrastructure.