“To unlock the real value of collaboration between the design and construction teams on challenging sites requires construction engineering – that is, engineering services to aid the means and methods of a contractor, but not typically the responsibility of an engineer or architect of record. This role bridges the gap between design intent and construction requirements and finds opportunities to make construction activity safer and more efficiently delivered.” – Dave Douglas, Associate

One of Construction Engineering’s earliest champions and founders at Entuitive, Associate Dave Douglas, works out of our New York office. Recently, we sat down with Dave to discuss trends he’s seeing in the New York City CE space.

Trend #1 – Challenging Sites

The physical map of New York City is not getting bigger. As a result, the number of “clean” sites available to developers and property owners for new developments is limited. Instead, new projects often require the demolition or retrofit of a structure that is already there, which adds unique challenges and extra steps to the development process.

These projects typically involve an investigation phase to determine what’s there on site before we can get to the design phase. We’re looking to understand things that typically impact the construction process like space, noise/vibration, protection, permitting, and sequencing. We must also account for the fact that during the investigation phase, new challenges can be found. And to further complicate matters, these buildings frequently remain partially occupied while construction is taking place.

While this is by no means an exhaustive list, these considerations take center stage in project scheduling, which informs the design intent and requirements. And, once we have this information, we can begin the process of working with the architect, contractor, fabricator, and other stakeholders to create a constructible design that will ensure a project is delivered safely and as efficiently as possible.

Challenging Sites in Action

At the Manhattan West Platform, Entuitive was part of a team that designed the solution to building on one of the most challenging sites in New York City. In this case, our challenge was how to build over an active railway corridor feeding the busiest transit facility in the Western Hemisphere. By incorporating segmental precast bridge construction, cast off-site and tensioned together on a temporary platform, and then erected via a moveable gantry crane, the team of construction engineers devised a way to minimize touchdown points at track level and lift the deck into place in 16 modules, each spanning the full width of the tracks below.

The crane load at the Manhattan West platform.

This technique was then turned 90 degrees at the 550 Washington site, where Entuitive once again employed segmental precast, post-tensioned concrete for the building’s new elevator and stair cores. In a first-of-its-kind application, this novel approach to building erection saved months on the schedule, permitted a single trade to erect both steel and concrete using the same crane, and allowed for core construction to take place off-site while other design work was progressing, and the enabling works were taking place at the existing building. Such an innovative building technique would not have been conceived without the artful interplay of both construction and engineering.

The first tilt table test at the 550 Washington site.

Trend #2 – Increased Use of Alternative Procurement & Delivery (APD) Methods

With speed-to-market being a common priority for owners, developers, and agencies looking to capitalize on market trends or funding opportunities, the building and infrastructure community is seeing an increase in the number of projects utilizing alternative procurement and delivery (APD) methods. While there are several methods, those most common in New York are Design-Build for projects over $10M and DBFM (Design-Build-Finance-Maintain) or P3 (public-private-partnership) models for projects over $500M. Also, construction managers are seeing the value of bringing in key trades during the design development to function in the “Design Assist” role.

The primary reason to pursue an alternative delivery method is to start and finish both design and construction work earlier. APD projects also allow for risks to be shared between the design and construction entities. Naturally, bringing together designers and contractors with a common goal engenders a spirit of collaboration that is not always present with traditional Design-Bid-Build projects, and this can often enhance efficiency when present. This relationship also provides an opportunity for both the engineer and contractor to revisit the traditional lines of responsibility for the strategic benefit of the team.

For example, construction staging diagrams or 4D modelling (a 3D model which is constructed and assembled virtually to show sequencing and validate design assumptions) can be incorporated into the designer’s role (after necessary input from the contractor), rather than delegated to a third party. When working in occupied buildings, a combination of construction engineering for the design of temporary works with construction-stage pedestrian modelling can be a powerful tool to demonstrate to authorities or external stakeholders that public safety and impact has been sufficiently considered by a Design-Build team.

Alternative Procurement & Delivery Methods in Action

Our experience working on signature projects in New York City (NYC), like the Moynihan Station gridshell skylights, has shown us the value of alternative project delivery methods because it provided an opportunity to implement construction engineering services. Moynihan was originally designed via a conventional procurement approach. As the project evolved and the parties coalesced, it became a design-build project, with the engineers, architects, contractors, and developers all aligned. The design engineers of the gridshell skylights who were a part of the design build team also provided design assist and erection engineering services to the specialty subcontractor who fabricated and erected the skylights. The various methods for teaming and procurement created the environment that ensured that the process would result in something both functional and beautiful.

Installation of the gridshell skylight at Moynihan Station.

On the Union Station Enhancement Project in Toronto, delivered under several project types including Design-Build and the Alliance models, Entuitive modelled the impacts to transit and station customers as a result of construction staging and barriers, using our dynamic pedestrian modelling capabilities. These models characterized and quantified the influence of construction activity on passenger behavior and platform clearance times, which ultimately assisted the contractor in their approvals for intended work plans and provided project stakeholders with a better understanding of interim project outcomes.

Trend #3 – Sustainability and the Growth of Retrofit & Renewal Projects

Local Law 97 was introduced in 2019 and requires buildings over 25,000 square feet to meet reduced operational carbon goals by 2024 and more ambitious goals by 2030. Many building owners are looking for ways to meet the new energy targets and to increase the value of their asset. One of the more prevalent steps being taken to achieve these goals is the introduction of high-performance building envelopes to replace outmoded or low-performing façades. Not only do these alterations breathe new life into a building, they also can significantly contribute to achieving a better performing building and a healthier living or workspace. Depending on the building, these changes can be achieved through either a removal and replacement of the existing façade, or through what is called an “overclad”. Often, they are applied to existing buildings which are at least partially occupied.

Entuitive’s experience with façade improvements has shown us that both strategies – re-clad and overclad – present their own benefits and challenges. In both cases what often drives the strategy, and the schedule, is the level of “invasiveness” into the occupied space within the building. This is where construction engineering comes into play.  A thorough understanding of the existing structure combined with establishing thoughtful means and methods for the construction activities, like those referenced above but also load checks, travel paths, temporary supports and rigging, use of cranes, etc., means that a building envelope team and owner will have the requisite information to devise a work plan. That work plan might then be shared with tenants or other stakeholders in advance of bringing a contractor on board. When a contractor has been selected, construction engineering acts as the conduit between all parties to bring innovation to life.

Sustainability and the Growth of Retrofit & Renewal Projects in Action

Entuitive has several examples of such projects, where we were involved inthe permanent design as well as the construction engineering of a façade replacement or renewal. One specific award-winning example is the MacKimmie Tower Redevelopment project:

The  project is a retrofit of an existing fifty-year-old library building at the University of Calgary. A specific point of interest is the double skinned façade (interior glazing line and 4’ wide interstitial space with exterior glazing), which has several innovative features, including active shading systems and fully automated operable windows both at the inner and exterior glazing line.

The MacKimmie Complex and Professional Faculties Building Redevelopment project continues in June 2019 at the University of Calgary.

Immediately after the existing precast panels and asbestos were removed, the interior glazing line was installed to ensure the building was enclosed as quickly as possible. This enabled work on the interior finishes to advance in parallel with the installation of the exterior glazing skin. As a result, the trades were able to work on the interior and exterior façade in tandem, thereby significantly reducing the construction schedule. In fact, the University used a phased approach to gradually allow staff to move into the new building. The building was half-occupied by U of C staff while exterior work continued. As is more common than less, understanding how these replacements can be accomplished with minimal interruption to building occupants can be as important as the replacement itself. Rationalizing approaches where temporary shoring or hoarding through tenanted space contributes significantly to the success of the project.

Thank you for sitting down with us today, Dave. We learned a lot!

Read more about Entuitive’s construction engineering services here. You can also reach out to Dave directly here.