The 101 York Road project combines a multitude of unique features and elements, including construction in a tight urban setting, complex site work and multiple building structures. From wood-frame construction to post-tensioned concrete, and deep excavation to an expansive retaining wall, this project required strategic planning and nontraditional solutions to get the job done.
Located in the heart of Towson, Maryland, 101 York Road is a new student housing building with:
- 248 units and a total of 611 beds
- 187,000 square feet of parking spread among four levels
- 10,600 square feet of retail space
- 9,000 square feet of amenity space, including a fitness center with tanning beds, an exercise room and four lounges
- An outdoor courtyard with a movie wall, gas fire pits, full kitchen, lighted game area, televisions and comfortable seating
- Three green roofs
Urban Setting, Site Constraints
Located on Towson’s main thoroughfare, this project is surrounded by Towson University, heavy vehicular and pedestrian traffic, multiple adjacent businesses, a Maryland State Highway Administration road and a local stream. In addition, the building’s footprint occupies 95% of the project site, leaving limited options for crane locations.
Reaching all areas of this building’s unique shape required the use of two tower cranes. Traditional tower cranes with horizontal jibs required air rights over the five adjacent properties – a Jiffy Lube, a Maryland State Highway Administration road, a residence hall owned by Towson University, a Starbucks and an American Legion. However, the air rights were unattainable, so an alternate plan was needed.
By utilizing tower cranes with luffing jibs, we were able to control the cranes’ reach and limit their movement, even when sitting idle overnight. This ensured the jibs did not enter any unauthorized air space.
These impressive cranes were 200-feet-tall (400+ feet from the concrete footings) with a 200-foot jib and lifting capacities of 27,000 and 36,000 pounds. Foundations for the tower cranes required between 180 and 240 cubic yards of concrete.
Due to the size of the cranes combined with the tight site constraints, no construction activities could take place while they were erected. Through thorough coordination and extended hours, erection of both cranes took only five total days.
Complex Site Work
Kinsley self-performed the site work, including clearing a wooded site, removing copious amounts of trash and debris, and demolishing an existing structure. Once the site was clear, our team was faced with a new set of site work challenges.
Storm Pipe: Erosion and sediment controls mandated that a new 60-inch storm pipe be in place and active prior to constructing the building. An added challenge, a portion of the pipe was to be installed directly above one of the building’s footings, which could not be poured prior to installing the pipe. By working with our excavation specialists, we designed a trapeze that suspended a temporary pipe above the ground, then excavated five feet below the bottom of the pipe to make room for the footing. By coming up with this creative solution, our team met the erosion and sediment control requirements while also keeping the project on track.
Retaining Wall Outfall: With a local stream running adjacent to the project site, the stormwater management system required installation of a 30-foot-tall retaining wall with a spill way to carry water from the pipe into the stream. Given the soft soils created by the stream, we drilled 55-foot, galvanized steel I-beam piles, set in concrete with reverse tiebacks, to support the wall. Typically, tiebacks are angled so they don’t interfere with construction and may be removed after they serve their purpose. With the wall sandwiched between the stream and the building’s large footprint, we had to reverse the tiebacks into our site and excavate around them. Once again, our team’s solution avoided project delays.
Support of Mass Excavation: The stream located adjacent to the site was re-routed roughly 30 years ago, leaving residual groundwater in the subsurface which resulted in excess water and soft soil conditions. Originally, the building was designed with undercuts between three and six feet, but due to the poor soil conditions, undercuts had to be between eight and 15 feet, pushing the limits of our support of excavation (SOE). By working closely with our subcontractor, the SOE was redesigned to include various systems on the site:
- Traditional cantilevered piles
- Piles with tiebacks (the system used at the retaining wall)
- Piles with whalers and corner bracing to prevent the use of rakers
- Piles with permanent rakers
- Piles with temporary rakers for undercuts, which were later filled back to foundation grade
With these systems in place, we excavated roughly 35,000 cubic yards of dirt to create the two-story, 25-foot, underground parking structure.
Construction Sequence: Originally, the building was to be constructed in a clockwise direction. Because we had to delay pouring the building footing until after the storm pipe was in place, we reorganized our sequence of construction and moved to the opposite end of the building footprint. This allowed building construction to move forward while we poured the delayed footing, helping to keep the project on schedule.
The building is comprised of three structures tied together, totaling 155 feet tall with 25 feet below grade. The main 15-story tower is a concrete support structure with post-tensioned concrete decks. Four- and five-story wood-frame structures are being built atop a four-story podium deck and located on either side of the tower.
The post-tensioned concrete creates thinner, stronger and longer-lasting slabs that will support large high-rise structures while reducing time and material costs. These are constructed by pouring columns and walls, then forming the deck using post shores and topping with a polished-finish plywood (for easy removal and a smooth concrete finish). Post-tensioned cables (or tendons) are set between layers of rebar at varying heights, concrete is poured and set, and is then stressed to create a post-tensioned, prestressed slab of concrete. To ensure the structural integrity of the building, bracing cannot be removed on any floor until it supports at least three levels of poured and stressed concrete slabs.
Between the building’s size and the multiple structures, the project has required a voluminous amount of material and an extensive number of contractors. Our team has utilized expert planning, coordination and problem-solving to ensure the project moves forward without delay.
We have recently completed two of the underground concrete slabs and have begun constructing the next two. These will be complete prior to construction of the two wood-framed structures, followed by the 15-story concrete tower.
Because we will eventually perform tenant improvements in the shell retail space, our virtual design and construction team worked with our subcontractor to use laser scanning to capture as-built conditions prior to pouring the slabs. Surveying these conditions will allow for a cost-effective and accurate pipe penetration design once the retail space is fit-out.
Proper Planning Gets Results
Despite its unique features and challenges, this project is on track for its original August 2020 completion date. For every situation and problem encountered, our team worked collaboratively with the owner, designers and subcontractors to ensure the project moved forward, avoiding delays and implementing recovery schedules when necessary.
At Kinsley, we meet schedules – no exceptions. This project is a testament of our dedication to overcome any obstacle to deliver a project on time.