Transforming rail on Manhattan’s East Side

Grand Central Terminal in Midtown Manhattan needs no introduction. With its Beaux-Arts architecture and breathtaking interior, the world-famous landmark is a mainstay in film and television, making it one of the top tourist destinations in the city.

Along with being a retail and dining destination on the east side, Grand Central serves five different subway lines and the Metro-North commuter rail from upstate New York and Connecticut. Prior to the pandemic, Grand Central saw around 750,000 commuters and visitors every day.

This hub of activity and transportation is one of only two commuter rail terminals serving all of New York — the other being Penn Station, where three different rail providers bring commuters into the city. New Jersey Transit trains arrive from the west using it as a terminus; Long Island Rail Road (LIRR) trains arriving from Queens and Long Island in the east also terminate here, and Amtrak’s trains use it as a through station on the route from Boston to Washington, DC.

With record levels of ridership, Penn Station is regularly overcrowded, as are the six different subway lines that connect here to take commuters to their offices on the East Side of Manhattan. The solution is the East Side Access program, the first expansion of commuter rail in New York in more than 100 years.

Completed in 2023, this megaproject provide new commuter rail service from Long Island and Queens to the East Side of Manhattan in a new, eight-track terminal and concourse below Grand Central Terminal, providing relief to Penn Station. It encompasses work in multiple locations in Manhattan, Queens, and the Bronx and includes around 9 miles (15 km) of tunneling.

The Metropolitan Transportation Authority (MTA) began planning the project as early as the 1950s, but more recently it has been the MTA Capital Construction agency — formed in 2003 to manage expansion megaprojects for the city’s transit network — that has been responsible for making it a reality. Constructing the required infrastructure is a feat in itself, but working in the midst of one of the world’s busiest cities presents additional challenges. Funding constraints and delays, and the involvement of third-party stakeholders, have added another layer of complexity to the project.

As part of the Program Management Consultant delivery team, Mott MacDonald handled both the engineering challenges and these project constraints by relying heavily on open communication, innovation in the face of adversity, and working collaboratively. Developing this project-wide culture and building trust has been the key to delivering the East Side Access project.

Background and vision

East Side Access has been years in the making, with the plans being refined and adapted.

East Side Access will route LIRR commuter services through new track connections in Queens, new tunnels under the Harold Interlocking (the country’s busiest rail junction), and through the existing 63rd Street Tunnel under the East River into Manhattan, where new tunnels will curve south under Park Avenue and enter a new LIRR terminal beneath Grand Central, which comprises two enormous caverns.

In an earlier iteration of the East Side Access project dating back to the 1960s, the LIRR trains would have ended their journey in the existing lower level of Grand Central used by Metro-North. However, with major financial problems plaguing the city in the 1970s, the project stalled until the 1990s.

In those intervening decades, patterns of commuter ridership changed significantly, and it became clear that the existing lower level terminal at Grand Central could not handle more passengers. The project therefore evolved towards building a bilevel terminal — essentially, two caverns — beneath the existing terminal's basement.

Other potential solutions were explored in the 1990s — including rail tunnels connecting Grand Central and Penn Station — but were discarded. One constraint was that when the 63rd Street Tunnel was originally dug in the late 1960s, using federal funding, it was stipulated that the lower set of tunnels (below the upper set that house New York City Transit's F train) were to be used for future LIRR service. If they were not used for this purpose, the money spent on constructing them needed to be returned — a requirement which meant alternatives to using the 63rd Street Tunnel were effectively ruled out.

Scope and expectations

Working within one of the world's busiest cities presented a host of challenges for the project team.

Mott MacDonald’s Colin Lawrence joined the project in 2000, as the Manhattan program manager and chair of the project-wide contract packaging and scheduling working group. Andy Thompson started on the project in 2006, initially as the package manager for one of the major tunnel construction contracts and later becoming a program executive appointed by the MTA. In discussing the scope of the project and the various complexities in its planning and construction, both are certain there is really nothing in the world like East Side Access.

The underground environment presented a host of obstacles and limitations, including high-rise buildings with deep basements, 100-year-old cut-and-cover subway lines built by rival private railroads, water tunnels and, in the instance of Grand Central Terminal, a maze of high-pressure steam tunnels.

“The planning for this project occurred pre-digital and even before computers. Understanding in three dimensions the underground constraints is a nightmare in Manhattan,” Lawrence says. “And East Side Access inherited these legacies. It’s easy to be clever now when we’ve got digital twins where you can see underground in a virtual world. We weren’t working with modern solutions.”

The construction could not cause any disruption to the already overcrowded transit systems in the vicinity of the project’s numerous worksites. No additional truck traffic could be added to Manhattan’s streets. Initially, tunnel boring machines (TBMs) had not been considered for the excavation, just drill and blast. This was the backdrop for delivering the largest public works project in the country.

An evolving solution

The new caverns designed for the East Side Access project are worthy of the iconic status of the station.

The project's signature component is the new 500,000-square-foot terminal at Grand Central. Its end users are not limited to rail providers and their passengers: There is space for retail in the concourse and the project team was dedicated to ensuring that the caverns would become an attractive destination that would acquire iconic status and blend into the historical Grand Central Terminal.

Inevitably for such a massive structure that has been planned over two decades and has so many third parties and potential users to accommodate, the project has continued to evolve over time.

As the team began to realize it was working with the practicality of blasting the entire project in a post-9/11 city, it pushed for the use of other additional excavation methods including TBMs and roadheaders, which would be a boon for the project schedule in years to come.

While the team determined the configuration of construction sequencing for the caverns in Manhattan, on the other end of the project it was doing much the same for the Harold Interlocking portion of the project. This portion saw between 15 and 20 revisions of track realignment to accommodate working in, around and under operational track.

“Given that all of that planning was going on in only a two-year time frame, it’s quite impressive that we got to the next stage,” Lawrence recalls.

Funding and procurement

Funding for the East Side Access project came from the MTA and the Federal Transportation Authority.

In 2002 it was agreed that the federal government would contribute $2.2 billion and the MTA would match it for a project budget of $4.4 billion. However, funding issues caused uncertainty in the years that followed.

The MTA is a state agency, funded by the New York State legislature on the basis of five-year capital plans. For a project like East Side Access with a long-ranging timeline, the budget needed to run across multiple capital plans. In 2008, as the financial crisis loomed, the MTA was in the midst of trying to secure the funding for its 2010-2014 capital plan.

It wasn’t until 2011 that the plan finally secured approval. The approved budget, however, was less than requested, meaning the project team had to review the upcoming procurement schedule and identify the components that were needed to keep that critical path going.

To extract noncritical works and repackage the contract to keep the critical path moving forward, the team decided to look five years out and work backward to help inform these difficult decisions. For example, without ensuring all necessary infrastructure was built to enable the SCADA backbone installation, nothing could be connected, so this was prioritized.

Dividing up the project

Originally the contract packaging envisaged a few large construction contracts.

The contract package to excavate the Manhattan caverns and associated shafts, for example, also contained clearing and demolition, building new access points and creating ventilation shafts, among other preparatory work. But when only one bid was received — which was above budget — the team decided to split this massive contract into seven, and procure each of them in the same time they had planned to procure the single contract.

The complexities of the situation continued to grow. Splitting out work created new predecessor contracts. “Immediately we had introduced seven interfaces that we didn’t have before, and all the difficulties and risk in managing those multiple interfaces,” explains Thompson.

Risk management

All underground construction contracts were procured as requests for proposals, and could be negotiated.

This was particularly helpful for the contracts covering soft ground tunnels in Queens, an extremely high-risk job. Through protracted negotiation sessions, risks were identified and risk-sharing mechanisms established within the contract.

“The biggest area of concern was on cutterhead interventions,” Thompson recalls. They agreed the first 800 hours of interventions would be covered in the contract price, and any following hours would be based on set parameters.

Working together they established the rates during the negotiations, and the program development team also established liquidated delay costs to further build trust between the contractor and the client.

“That particular job did not have a geotechnical baseline report because they were using slurry TBMs,” Thompson says. “Instead we baselined the contractor’s schedule and required them to submit very detailed cycle times together with cutterhead usage, tool usage, cutterhead interventions, and so on, as part of their bid. This became contractual as part of the contractor’s schedule.”

The program team reached an agreement with the contractor that if they could prove the ground caused delays based on this schedule, there would be potential for a claim. And in the end there were none. “In fact, despite all the underground work we did, there was only one minor successful differing site condition claim across the $2.2 billion of underground work on the project,” Thompson says.

“That’s the attention to detail we had on all the jobs in terms of potential for risks, how we wrote contracts and that changing ground condition clause. We wanted to make it as easy as possible to assess, pay, and resolve.”

“This approach worked because on our side of the fence we had people with a lot of experience and an understanding of how that risk could go wrong, and how it could be managed,” he explains.

Aboveground restrictions

Just beyond the 63rd Street Tunnel in Queens is the Harold Interlocking and Sunnyside railyard, a 1.5-mile-long rail junction that sees more than 800 trains per day.

East Side Access effectively extends the 63rd Street Tunnel by about one mile by excavating new tunnels under the existing bilevel facilities. However, before the project could even begin to tackle these engineering challenges below ground, the junction required extensive upgrades.

The way the Interlocking previously operated, Amtrak trains had to cross over the LIRR tracks before entering the East River Tunnels, which are south of 63rd Street.

Should either rail provider have an issue with a train, both timetables would be impacted. As part of East Side Access, the MTA built new cut-and-cover tunnels for the rail providers to bypass and reroute around each other. Other reconstruction work installed five miles of new tracks, as well as building and updating support structures including access roads, power substations, ventilation facilities, and new systems for communications, signals, and power.

800 trains per day going through Harold Interlocking and Sunnyside railyard

As part of this agreement, the MTA also committed to doing all the upgrade work, the rerouting, and the tunneling with no adjustments to the operational timetables of the trains through the junction. From an engineering perspective this was no small task, and the challenge really bloomed when the program delivery team fully understood the logistic and resource constraints they were facing.

Limited to requesting night-time and weekend outages, as part of the project delivery they established an entire team dedicated to planning and managing all of the railroad outages, including people solely focused on scheduling the work in the junction.

Both LIRR and Amtrak had finite resources available to support work not only on the East Side Access project but on their other capital and maintenance projects. Planning for the use of resources was undertaken in the months ahead of planned outages. However, unplanned staff absences, for example due to crews focusing on snow clearing or service restoration after storm events, could cause a planned outage to be canceled, leading to knock-on schedule effects that could prove difficult to recover.

This complex work at the Harold Interlocking, and its extensive stakeholder management, was a major driver of schedule issues on the project. Any time the project team couldn’t take advantage of planned outages, substantial time was lost in the schedule.

While there were no alternatives or solutions for completing this work when third-party resources were limited, the project delivery team found ways to be agile and sought out opportunities to save schedule elsewhere.

Connecting Queens underground

Tunneling work has been performed by rock and slurry TBMs, sequential excavation method through frozen ground, and a combination of blasting, roadheaders, and even a TBM in the mammoth caverns.

To connect the mainline tracks in the Harold Interlocking to the existing 63rd Street Tunnel, two separate contracts were awarded to mine through Queens’ boulder-ridden glacial till and manmade fill. Two slurry TBMs, each 23 feet in diameter, excavated four running tunnels for a total of about two miles, with precast segmental linings. These machine configurations were a first for the local mining workforce.

“Slurry TBMs potentially offered greater control of ground movement than an Earth Pressure Balance Machine (EPBM)," Thompson says. “This was particularly important for passing 30 feet beneath the 60-mile-per-hour tracks in the Interlocking.”

To undertake this highly-complicated stretch of tunneling, the program delivery team relied on a collaborative approach with all stakeholders, as well as its innovative baseline method in place of a Geotechnical Baseline Report.

The soft ground tunnels contract was completed on budget and ahead of schedule. However, for these tunnels to connect into the existing 63rd Street Tunnel, the alignment needed 37 to make one more critical crossing under a major highway, Northern Boulevard.

This section is only 120 feet long, but required an excavation 66 feet wide through soft ground with sprayed concrete lining — another first for New York. Above the crossing is a five-track cut-and-cover subway box, the highway, and an elevated metro line. The bottom five feet of the excavation was in solid rock. “The risk and complexity of this is difficult to quantify, but it is very real,” Thompson says.

The elevated metro line was supported by the subway box and piles, and the excavation would have to mine through those piles to cross the highway. Collaborating with the contractor, the designer, specialist contractors, and numerous third parties, they developed a solution for supporting the infrastructure above ground, using ground freezing to create a freeze arch around the excavation under the subway box.

“We also drilled compensation grouting holes so if the freeze heaved the subway box upwards, we could inject hot water,” Thompson explains. “At the same time when we later took the freeze off if we had any settlement we were prepared to do grouting to compensate to jack the subway box back up.”

Next the contractor had to underpin the elevated subway in preparation for mining through the piles, which it successfully did, completing the excavation without any major settlement nor disruption to the transportation above it. The crossing took three years and worked out to be almost one million dollars per foot to excavate.

Tunnels take Manhattan

On the other side of the East River the geology is drastically different from the soft ground of Queens.

Excavating in the Manhattan Schist, which varies in strength from 68 to 275 MPa, the contractor did eight separate TBM drives ranging in length from 1,600 feet to  1.5 miles, working out of a shaft in Queens at the east end of the existing 63rd Street Tunnel. Contractors built all of the underground works in Manhattan by bringing every building material through the tunnels and carrying the muck back out with conveyors.

7 miles of running track mined

43 feet production rate, averaged per day

From the 63rd Street Tunnel they have mined approximately seven miles of running tunnel. The contractor launched the TBMs in a starter chamber made by enlarging part of the existing tunnels and mined toward 5 Wye, a vertical separation point where the running tunnels split into the upper- and lower-level drives.

From this point, four tunnels head south beneath Park Avenue. Shortly before entering the station caverns, there are crossover caverns at both the upper and lower levels. Once through the crossovers, the running tunnels bifurcate and four tunnels pass through the caverns on each level before the eight tunnels reunite to create four tunnels that run to 37th Street.

The contractor selected two hard-rock TBMs with a combination of rockbolts, mesh, and full-circle steel for the initial support. In reality, less than 5% of the tunnel needed the full-circle ribs, and they were used in areas where the pillar between tunnels was less than eight feet to provide resistance to gripper loads. TBM operations were undertaken on a five-day, three by eight-hour shift basis and production rates averaged 43 feet per day.

“A major challenge was relaunching the TBMs, as there was no shaft at the southern end, meaning that the TBMs had to reverse through the completed tunnels,” Thompson says.

The contractor removed segments from the cutterhead, creating sufficient clearance to enable one of the TBMs to reverse. For the other, a shielded TBM, they needed additional clearance. While they would be able to remove the steel ribs installed during mining, this would require a staged re-support to be created, using rockbolts drilled into rock with mesh and sprayed concrete lining before dismantling the ribs. For this they used a custom-built gantry to ensure workers stayed under supported ground.

Phasing these TBM backups and providing connections between the tunnel drives had to be carefully planned because access ahead of the TBM would be blocked.

“At times only one tunnel was available for mucking and material delivery to the active TBM and the relaunch operation,” Thompson explains. “Because there were a number of locations where the future running tunnels bifurcated and caverns had been excavated, we could create the space that we needed to do these relaunches.”

Two methods were used to create the space for TBM relaunches in the wye caverns. The original design of the wyes provided enough space for them to be reused for relaunch with only a short starter tunnel required to create gripper pads.

After they completed the first relaunch and the TBM had mined through the cavern, the contractor could use a roadheader to excavate to the finished dimensions. The success of this inspired the contractor, designer, and MTA to revise the excavation method for three more TBM relaunch locations and where they mined through the lower-level crossover.

This method involved reversing the TBM to a location upstream of the relaunch location, installing a concrete plug in front of the TBM, then driving the TBM into and through the concrete plug. “This gradually engaged the cutterhead into rock along the new alignment with the plug acting as a temporary gripper surface,” Thompson says.

Once this method was proven, they redesigned the permanent structures to take advantage of the reduced excavation profiles and some 530,000 cubic feet of excavation was eliminated at each wye and crossover location. Besides significantly reducing the amount of excavation required at the wye caverns, the use of the plug reduced the time needed for TBM relaunch from four months to six weeks.

With these wyes and crossovers located below the main interlocking for Grand Central Terminal, the alternative to blasting proved beneficial for numerous stakeholders and third parties.

Cavern sequencing

Another constraint, familiar to any tunneling project in any city, is that contractors needed to excavate these caverns plus the approach tunnels, five escalator shafts, and construct a concourse without a laydown area. Thompson describes it as “building a ship in a bottle, with the cork in it.”

The MTA’s Environmental Impact Statement declared there would be no additional truck traffic to Manhattan. Cavern construction overlapping with TBM tunneling on the Manhattan side of the project prevented access for cavern contractors to the worksite in Queens. This created an immense problem for delivering supplies to the Grand Centeral Terminal’s cavern worksite.

With the sheer amount of concrete needed on the project, it was recognized that it would not be possible to bring concrete through the existing tunnel. The team managed to secure a revision to the Environmental Impact Statement to accommodate concrete and explosives deliveries, but trucking muck through city streets remained restricted.

The solution required not only ingenuity on the part of the project delivery team, but also building trust with rail providers. For the concourse built at the lower level of Grand Central they had direct track access from a previous midday storage yard where they could maintain two tracks through the construction period.

“We bought 25 train cars and two locomotives that were purchased for Metro North RailRoad,” Thompson explains. “We actually operated our own railroad.”

The railroad connected to a staging area about nine miles north of Grand Central in the Bronx North Yard. All supplies including site offices, reframing steel, glass, marble, and even portable toilets traveled in and out of the city on these railcars.

While innovative, this solution did bring further demand for precise and well-prepared scheduling. The program delivery team hired a company to run the railroad, and set up a team to coordinate every load with every contractor, 10 days in advance, which was the only way they could guarantee availability on the six railcars it could run at one time.

Initially the rail provider offered two train trips per day, which wasn’t near the capacity needed. Collaborating with Metro-North and adhering to a strict timetable, they were able to run these deliveries into and out of the city in between the commuter trains.

It was a massive logistical challenge that also required every car and load to be inspected before it was allowed on the system, to ensure everything was properly secured and nothing would cause a disruption to the regular service. “That’s a contract in and of itself on a lot of other projects, but it became just a normal, everyday thing that we did,” Thompson says.

Even with concrete trucks allowed in the city, thanks to the EPA waiver, the team still faced the logistical challenges of the busy city streets surrounding Grand Central, and the lack of aboveground access to underground works. The project delivery team investigated the surrounding streets for any locations where they knew the subsurface provided direct access to the project, and that the road width had ample space for them to take a lane with minimal traffic disruptions.

Working with the Department of Transportation, the project delivery team would take possession of a parking lane, screen it off from the public, break out an access hatch in the sidewalk and create concrete drop pipes. These five facilities allowed the trucks to deliver concrete, in some cases for up to three years.

However, this did require proactive third-party management — Grand Central’s neighbors include well-known financial, commercial, and other institutions — as well as stakeholder coordination. At the same time, these drop pipes had to be shared by the project’s various contractors. The team maintained ample resources to ensure this ran as smoothly as possible.

“One entire part of our schedule was concrete drop pipe availability,” Thompson says, “we had to be efficient.” The caverns are more than 1,200 feet long, 66 feet wide and 66 feet high, and will house eight platform tracks. In some locations, these have been constructed with as little as 43 feet of rock between the cavern arch and the operational tracks of Metro-North Rail above them.

Drill and blast excavation in Midtown Manhattan, beneath the city’s historic and beloved rail station, with live rail operations, made many people nervous. The project team relied on extensive coordination with third parties, collaboration among stakeholders, and a groundbreaking approach to instrumentation to maintain trust and keep the project moving forward. Working with Metro-North, as well as the New York City Fire Department, they established a schedule between trains of 20-minute windows to blast, up to five times a day.

Once the caverns started opening up the project could sink shaft 5 to meet the TBM drives, providing a new access to the underground for the workforce. The project delivery team saw an opportunity to reduce the number of blasts they’d need to do by driving the TBMs through the caverns.

“The TBM bores gave massive relief to the blasting,” Lawrence says. “From a peak particle velocity perspective it really helped reduce it.”

He explains how this solution also stemmed from needing to correct a scheduling error based on faulty excavation methods. “The original concepts called for burn cuts on the caverns, with long round lengths, which wouldn’t have worked, but the original schedule assumed they would,” he says.

In the end the contractor performed 2,365 blasts without causing a single train cancellation or delay, nor any damage to Metro-North’s rail operations. Reusing the TBMs saved time. And the project continued to move forward into the next phases.

Collaborative environment

The team attributes their ability for finding alternatives to save time or overcome an obstacle imposed by a third party to the environment they created on the project.

“Looking back at the things we did, so much of it was really challenging, and we just took it in our stride,” Thompson says. “We had a very good team who rose to the challenge and we tried to encourage an atmosphere where people were prepared to bring solutions to the table, no matter how off the wall.”

No more so is this true than in the instance of the cavern walls. Going against the grain of conventional wisdom in both New York and London, the team introduced sprayed concrete lining using hand spraying techniques, over standard rebar against PVC membrane. “We found a way to do it because we had so many complex shapes in the wye caverns, which were constantly changing.”

Finding an effective way to use sprayed concrete lining had an array of benefits for the project’s schedule. They could change the geometry of the wyes and use the TBMs to mine them, eliminating formwork, which would have needed to be up to three stories tall.

Without the formwork there was more access space in the tunnel because the nozzlemen used scaffolding to spray the shotcrete. “We cut out 20,000 cubic yards of excavation, which is schedule, which is time, which is money,” Thompson says. “This is nothing brand new, but it’s the way we got everyone to work together to use it in the caverns for the fit-out that’s so significant.”

They developed a hybrid design where all vertical elements were either cast in place or shotcreted, while all the horizontal elements — what was needed to create the bilevels — were precast. This required bringing 6,000 pieces of precast, driven through the tunnels from Queens to Manhattan, on the back of trucks and installed in the caverns. “We did all the concrete in both caverns in nine months,” Thompson recalls. “And because we did precast for those pieces it was a much better finish.”

Conclusions and outcomes

Mott MacDonald, as part of the program management consultant team, oversaw 35 separate construction contracts.

This included pre-contract packaging and chairing the contract managing working group for developing 75 contract packages. These range from the $1.2 billion Manhattan tunnels construction package to a $2 million instrumentation installation contract in Queens.

Extensive and detailed planning over the past decade enabled this complex and stealth tunneling to take place. While open communication and a spirit of collaboration were both valuable for the project, the team nevertheless encountered constraints with third parties that could not be negotiated.

The solution was to rely on innovation, which could only be delivered by gaining the trust of the client and contractor. “While risk management was applied to the job, there was nothing to draw from, in terms of what are all the risks that could impact the schedule or the budget,” Lawrence concludes. “This project is an achievement. It’s unprecedented in terms of the scale and complexity, as well as what it will provide for New York City.”

From the extensive upgrade work in the Harold Interlocking, which eases conflicts between rail providers, to discreetly blasting below active rail operations in Midtown Manhattan, the project delivery team made sure no commuter’s daily journey to and from work experienced disruption related to the project.

“It’s all about attitude and ability,” Thompson says. “The team was capable of thinking three months ahead in the schedule, and they knew each contract better than the contractors because we needed to build a working relationship with our stakeholders. That’s the only way we could succeed, by helping our contractors to succeed. And we developed that culture.”

This culture extended beyond the client, contractors, and third parties. The team improved the safety culture on the project, and created safety measures that MTA Capital Construction later adopted on other projects.

With Thompson in a project executive role they also established stronger and more proactive resources for public outreach by increasing the full-time staff doing communications, holding more open days, and creating a public website for progress photos and updates.

The project on January 25, 2023, opened with limited service to Jamaica Station in Queens. Full service began on February 27, 2023. Ridership was expected to serve as many as 160,000 commuter trips per day. Commuters from Long Island now have a one-seat ride to Grand Central and the upper east side of Manhattan.

With the completion of East Side Access, the MTA can move forward with other projects to improve transit in the region. For example, the Penn Station Access project would add four new rail stations in the East Bronx, significantly cutting travel times to and from Manhattan.

$11.1 billion estimated cost at completion