After two and a half years of construction, preceded by decades of proposals for the site on which it now resides, 150 North Riverside is open for business in downtown Chicago.

The 54-story, Class A office tower, located at the confluence of the three branches of the Chicago River, is significant - perhaps even remarkable - for several reasons:  it adds 1.2 million square feet of office space to the heart of the city; much of the site is devoted to a new public park, amphitheater, and river walk; its cantilevered design and rippling facade have already made it a Chicago landmark; and it was built on a notoriously challenging, hard-to-develop tract of land that has sat vacant for many years.

The skyscraper, which Chicago Mayor Rahm Emanuel has called "the newest jewel in Chicago's architectural landscape" rises on the eastern edge of a 2-acre site on the Chicago River's west bank. 150 North Riverside offers 1.2 million feet of high-quality office space, but with its unique superstructure design, only covers 25 percent of its site - thus meeting the city of Chicago's requirement that developers set aside part of lot size for public park space.

Designed by Goettsch Partners, the building features a modern architectural style with steel structure, concrete core construction, and floor-to-ceiling glass. The building's facade has a rippling texture, created by undulating fins affixed at each vertical mullion in the unitized curtain wall system. Its lobby is surrounded by a structural glass fin wall system.

Construction on the project started in the summer of 2014, with the foundations and river wall reconstruction.  Work on the tower commenced in the spring of 2016 and was completed this past January.  Tenant contractors began their construction on the individual floors in the fall of 2016, and the first tenants moved into the building in February of this year. 

A Less Than Ideal Site

The land where 150 North Riverside now stands sat vacant for decades, largely due to its "hemmed-in" location. The lot, which is only 85 feet across at its widest point, sits adjacent to the Chicago River; seven active railroad tracks run directly through the site; and three elevated roadways border its north, south, and west sides.

Throughout the last several decades, many developers believed that building on a site with such constrictive features was highly improbable. However, this did not stop others from trying, says Tony Scacco, Executive Vice President of Chicago's Riverside Investment & Development, the firm that ultimately purchased the parcel and two adjacent parcels which consisted largely of air rights above the rail lines.

"This is one of the last trophy development sites in Chicago," Scacco states.  "It's in the heart of the city, it's right on the river, and it's at the center of a transportation hub. But the site came with a lot of fundamental technical complexities. It's adjacent to the water and to the railroad tracks. There were no utility services to the site because of the tracks, and only one surface road into and out of the site."

Riverside's purchase of the air rights above the adjacent Amtrak tracks facilitated the construction of an overbuild, ultimately destined to house a hidden parking level topped by a green plaza, but utilized during the construction phases as a surface-level staging area by general contractor Clark Construction Group and its various subcontractors, Scacco explains.

"The defining feature of the building is the base and the superstructure design. This helped solve the site constraints that prevented development on a very prominent Chicago site for close to 80 years."

In addition to Riverside, Goettsch Partners, and Clark, the project team included structural engineer Magnusson Klemencic Associates, MEP consultant Cosentini Associates, landscape architect Wolff Landscape Architecture, and lighting designer One Lux Studio. Scacco reports that the team worked very closely with Chicago alderman Brendan Reilly during the intensive planning of the project's outdoor spaces.                                                                               

Innovative Design Creates Smaller Footprint

A signature facet of the 150 North Riverside tower is the way the office floors cantilever out from the central core. While the building is constructed with a smaller base for its first seven stories, it then cantilevers out to the full size of the office floor space. This design features a small building footprint that allows for a dramatic, light-filled lobby while providing efficient, column-free office floors above. Emulating the river, which the tower overlooks, vertical mullions undulate along the building's east and west facades.

"How the building meets the ground, and how it interacts with its surroundings at the base, is an important aspect of this project," comments Joachim Schuessler, Principal at Goettsch Partners.  Below the eighth floor, the building is driven by the site, while above that it is more typical of Chicago office buildings.

"Riverside wanted the best office building in Chicago, both in terms of aesthetics and efficiency.  Our goal was to provide an urban space that interacts with the surrounding urban area and contributes to the city - not just a space that could be walked through, but with additional elements to experience." 

Goettsch has previously worked with executives at Riverside Investment & Development on several other Class A office building projects, Schuessler reports, and has established its expertise in such projects over the last decade. Over the course of the design process, many community meetings were held between his firm, the developers, and city officials.                     

A Mammoth Feat of Engineering and Planning

Construction of 150 North Riverside was indeed a feat of engineering, complicated by tight constraints, the risks and challenges of building on top of tracks, and off-peak hour construction necessitated by the location. Chris Phares of Clark Construction Group, who served as the Project Executive, reviews some of the issues with which his team was confronted.     

"It was a very difficult site to access and build on. There was not a lot of land to work with, and there was a rolling embankment into the river.  We had to stabilize the land to be able to work from it.

"The area is a busy railroad hub with multiple tracks," he continues. "Plus, there's an elevated light rail on the north end of the site. But we looked at every constraint, particularly the river, as an opportunity."

One significant way the Clark team kept the project on schedule, Phares reports, was by developing a floating platform system that allowed them to place a 662-ton Manitowoc 888 Ringer Crane on a barge in the river as a lifting platform.

In addition to constructing 150 North Riverside, Clark completed infrastructure improvements, reconstructing the site's river wall and upgrading several traffic and pedestrian signals. Additionally, the team completed the final link in the city's riverfront pedestrian walkway system by connecting to the river walk at River Point Plaza, which Clark constructed under a separate contract. 

A major component of the project's infrastructure was in the creation of the plaza, which capped off the railroad tracks and isolated them from the site. Says Phares, "No vertical construction was done until the tracks were covered. The plaza overbuild also tripled our staging area and allowed us to use a big expanse rather than a small sliver of land.

"We worked a lot with Amtrak around their schedules, and they also moved some trains to different tracks. We're happy to report that there were zero train interruptions over the nine-month period from grade to track cover."

He also points out that the 150 North Riverside project used the highest capacity micropiles - at 300 tons - ever used in Chicago, and 70 KSI structural steel was utilized for the first time in the United States.

A New Icon for the City

150 North Riverside has now taken its place among Chicago's architectural icons. It is already featured in architectural boat tours, and has been called by one architecture critic as "a persuasive blend of the pragmatic and the dramatic." The firms that teamed up to bring this project to fruition see it as a positive response to changing philosophies for urban buildings.

Scacco states, "Our objective as a developer is to create places and spaces that help occupants and users go about their day efficiently.  Urban areas now expect more of their office spaces, and it's incumbent on us to use good design and planning."

"Cities are getting increasingly dense, and sites are more complicated, so we have to learn to find new solutions," says Schuessler. "Policies and regulations are now meant to make cities better for the residents, and 150 North Riverside does an excellent job of this." To these comments Phares adds, "This project is a great example of where urban centers are heading, requiring more imagination from developers, designers, and builders to utilize sites like this amid dwindling available land."