Bridge construction projects have considerable impact on the public, creating longer travel times in congested work zones and increasing the risk of accidents. Full-depth precast deck panel systems offer short construction times, high-quality plant production, low permeability, less variation caused by shrinkage and temperature changes during initial curing, and lower maintenance costs as compared to traditional methods.
The New York State Department of Transportation (NYSDOT) considers accelerating projects wherever possible to save time and minimize traffic disruptions. NYSDOT supports usingAccelerated Bridge Construction (ABC) practices where they result in a net positive outcome. As per the Governor’s “Driver’s First” initiative, “any increase in construction costs associated with using an accelerated schedule is weighed against the resulting reduction in traffic congestion and delays,” explains Nick Choubah, PE, NYSDOT Region 2 Regional Director.
Choubah adds, “While it isn’t feasible on all projects, it may be possible to reduce both the time a roadway is out of service and overall construction costs using ABC techniques. For example, prefabricated bridge elements eliminate the need to wait for cast-in-place concrete to cure. In some cases, entire structures have been built off-site and floated in on a barge or wheeled into place in only one day.”
To decide which projects warrant ABC, the total value of the project as well as individual constraints are evaluated. Given the width of this structure, using traditional methods on Route 8 would have taken several stages and lasted 1- 2 construction seasons. The benefits to the travelling public outweighed the additional cost of ABC.
The goal of this project was to maximize the service life of the structure while minimizing construction impacts to the traveling public. Precast concrete fit into this scenario as one of the tools available. By using precast concrete deck elements, approach slabs, and Ultra-High Performance Concrete (UHPC) closure pours, the bridge deck could be removed and replaced in only 4.5 days. The Route 8 bridge was closed on Friday at 6 p.m. and opened to traffic again on Wednesday morning at 6 a.m.
“We required that the contractor perform the deck replacement over a weekend to reduce weekday traffic disruption,” explains Jimmy Piccola, Public Information Officer NYSDOT.
Fort Miller cast the precast bridge deck panels, center median barriers, and approach slabs. The precast components were delivered to a staging area a short distance away where they were stored on trailers awaiting installation.
Rich Anderson, President of Vector Construction Corp., the General Contractor recalls that “the schedule was originally 84 hours and was actually completed in 95 hours.”When the construction duration is measured in hours and not weeks or months, even minor issues stand out. UHPC was specified for shear keys and panel to panel joints. There were some issues in the flowability of getting it into the small pockets. “It took longer than we expected and when the sun came up the mix was starting to set up and got sticky,” describes Anderson. Ultimately the UHPC was poured a ½ inch higher and the precast deck was ground down for a smooth riding surface.
“We had all of our crews on hand for this one,” says Anderson.The existing deck was removed and the substructure needed only minor repairs. “The single span remained in place, but there was a bit of delay while we waited for the concrete to cure that was used to cap the back walls. Then we were ready to erect the precast deck panels as well as the precast approach slabs,” describes Anderson.
The Route 8 Bridge included details recently developed by NYSDOT for this type of project. “Any time we are rehabbing or building a new deck we try to remove the expansion joints completely,” says Choubah. The details on this project lent itself to the use of a “jointless over the backwall” detail that accommodates thermal movement while avoiding the long-term maintenance of an expansion joint.
The crane set up in three locations to install the precast pieces. From below on Genesee Street as well as one set up on each end of the bridge.
Some of the precast deck slabs contained an integral median barrier. Because the bridge had been widened, a side bridge railing was specified to minimize load on the structure.
It was a very tight schedule especially with the sub-contractors that had to be coordinated. There were subs on site to install bridge rail, as well as for grooving and grinding. “Originally scheduled in the morning, they had to be pushed back to afternoon,” says Anderson.Looking back, he believes that it could not have been achieved without the precast panels.
Extensive public outreach made a difference and was positively received. Residents were impressed that the impact was reduced from a potential 2-year construction schedule to a long weekend. Many locals watched the progress with fascination over the brief 4.5 days of construction.
In addition to minimizing the impact to the community, we also coordinated with first responders and all other stakeholders,” explains Piccola. The bridge is vital to the village of New Hartford and just north lies the city of Utica. “Six to eight months in advance we were getting buy-in from residents and their interest was piqued to see how our team could pull this off,” says Piccola. While the detours were not long depending on travelling direction, the benefits to the travelling public were key. The schedule also intentionally avoided special events and was wrapped up before school started.
With the location of the bridge in the middle of the village – there was the additional impact to business owners as well as the travelling public. A portion of Genesee Street was closed for the duration of the project and the on-off ramps were used to divert traffic northbound. While the impact was significant for short duration, weighed against a long construction schedule, the public, media, local officials and residents were on board.
The construction industry has become more familiar with and more comfortable with aspects of ABC including the use of precast full depth deck panels. NYS and other DOTs are using “best value” instead of a low bid process. In combination with ABC, the process leads to an increased pool of interested contractors. For projects like this where schedule is critical, using “best value” results in the most advantageous outcome considering technical, cost, and other evaluation factors.
Working with Fort Miller to optimize the precast concrete design and construction, much of the effort was front loaded and completed before August 17, 2018 in order to make everything run smoothly during the critical path of the long weekend on site.
“Our goal is to provide the most durable, cost-effective structure possible while minimizing construction impacts to the travelling public. For this accelerated bridge deck replacement project, precast concrete deck panels helped to achieve that project goal to maximize service life of the structure while minimizing construction impacts to the traveling public,” summarizes Choubah.
Given the success of this project, the use of precast and ABC are tremendous tools to have in the arsenal. To replace the whole deck in 4 ½ days was a challenge but rewarding to see the final result. “This was the first project in our region and we look forward to doing more of this sort in the future”, says Choubah.