The Promenade Apartments

One of the items that makes this such a desirable location for tenants also created one of the biggest obstacles for executing the work, perhaps one of the reasons why the work had never been tackled in any year prior. The building boasts an additional, separate elevated structural deck immediately along the river that runs the entire length of the main plaza, accessible from a staircase that comes down off the main plaza. This veranda places the viewer right alongside the water, albeit 50 foot in the air above the river. It’s only when you hear the sound of a transit train’s horn is when you realize you are literally standing above the MTA’s train tracks on the ground below.

With active train service nearly 24 hours of the day, and with a significant portion of the plaza cantilevering over these riverside rails, the protection of these tracks with the installation of a protective barrier was a major work items for this project. A special set of track space entry permits had to be issued by the MTA. Contrac¬tor’s crews needed to be trained not only on the installation of the protective platform but also on the rules of safe entry over the train tracks. This platform protection could only be installed while the train service stopped running for the day, and work activity had to cease if a train had to use that corridor at any point during the 11pm to 5 am. Additional measures had to be taken if concrete demolition had to take place over any of this platform.

After the concrete topping was removed, the old waterproofing needed to be stripped off. Utilizing 3’ diameter planetary grinders attached to large dust collecting vacuums, the membrane was cut off structural concrete sur¬face. After all the overburden had been stripped away and the old waterproofing removed and disposed of, the structural repairs could take place and the new drains installed. The plaza parapet wall required stabilization, and the new parapets and curbs could be installed. After these conditions were all met, the new waterproofing membrane could be applied. The waterproofing used was a polyurethane, polyester reinforced system. With the help of a saturator, the installation went smoothly with large areas of waterproofing being installed on a daily basis.

One of the original issues discovered during the initial survey was the corrosion of the steel framed, concrete pedestrian bridge, which served as the primary entrance for tenants to access the building main lobby. The steel beams connecting the bridge to the plaza structural steel had deteriorated significantly, mainly due to the failed expansion joint between the bridge and plaza, and years of utilizing snow and ice melt.

The entire pedestrian bridge was deemed unsuitable for service and hence demolished and removed. New Steel beams were brought in for the elevated bridge spans, and the connecting girder and support column at that corner of the plaza were spliced with new steel sections. The pedestrian bridge was widened to maximize the width of the entry, which could not be accommodated using metal decking. The concrete deck had to be formed and poured, so with the help of wire saddle hangers that rested on the new steel beams, the bridge deck could be formed without have to shore down to the ground over 30’ below.

The building entrance was also widened where it met with the city sidewalk at the entry point. Ownership was insistent on creating clear lines of sight from the city sidewalk straight to the front door of the building lobby, so a portion of ledge rock was also removed so the sidewalk could be widened at that location. The remaining rock would then serve as the backdrop for the building’s new sign, which would mount to a bracket that was anchored directly into the exposed rock. 

The pedestrian bridge was completed with traffic coating for extended service life also. A new aluminum guard wall was installed using anodized aluminum railings and decorative panels to match the ones throughout the plaza. New aluminum light posts were also incorporated into the fence design and provided light to the pedestrian bridge after dark.

The parking garage was also rehabilitated extensively. Full depth concrete repairs throughout the 100,000 SF garage were executed while maintaining occupancy for the buildings tenants. Brokk robotic breakers were again used to break structural slabs and skid steers were used to shuttle the debris to the hoppers and debris chutes with numerous drains added throughout the garage as well. 

Throughout this project, the primary method for getting ready mix concrete to the work locations was to utilize a concrete pump. Steel concrete pipeline was attached to be buildings framing starting at the sub cellar, and was run vertically to the different levels of the garage and the plaza. When concrete had to be poured, the pump was brought below the building and connected to the pipeline, and trucks would drive under the building and discharge into the concrete pump. The pump was used for various size pours throughout the duration of the project. 

Once the structural repairs in the garage were complete, new expansion joints with cover plates were installed at all the joint locations. There were vertical repairs along the perimeter spandrel beam/curb, and new bollards and fencing installed as well. Finally, a traffic coating was installed to preserve these repairs and give the garage an extended service life.