Philadelphia Freedom

The City of Brotherly Love welcomes completion of I-95’s “missing link.”

B. Pietrini & Sons Concrete Pumping has made a solid name for itself pumping some of the tallest buildings in the Philadelphia metropolitan area. So it’s a bit ironic that the company responsible for getting concrete to the top of the 58-story Comcast Tower would also prove invaluable pumping 40-feet up to an elevated road deck. Working as a subcontractor to James J. Anderson Construction Co. Inc., Pietrini is using a number of boom pumps to tackle the final segment of a groundbreaking highway job in downtown Philly — but capitalizing on the inherent strengths of one unit in particular. When complete, the company’s performance will be an example of how truly “far reaching” a pump’s advantages can be.

Filling the Gap
Built in the 1960s, the Girard Avenue Interchange is a key artery in the Philadelphia metro highway system. The interchange, which parallels the Delaware River on Philadelphia’s southeast side and handles nearly 160,000 vehicles day, is undergoing a massive rebuilding process which, when complete, will greatly improve capacity, safety, and city access. It is also a component of a larger overall effort designed to fill the only remaining gap in I-95’s 1,900 mile trip from Miami to Maine. It is this long-standing headache that the Pennsylvania Department of Transportation (PennDOT), is working to change. According to Bill Smith, superintendent for James J. Anderson Construction (JJA), the new interchange will resolve a host of issues.

“This structure has been a sore spot for anyone who either lives here or regularly travels through the city,” he said. “Since its initial construction, the offramps from the interchange have dumped traffic down to red lights, almost always resulting in traffic being backed up onto I-95. It was pretty much obsolete by the time it was built. Granted, it was better than going through surface streets but there were a lot of problems right from the beginning.”

The Girard Avenue Interchange has been considered for reconstruction many times in the past but, because there is so much industry in the immediate area and because of the effort needed to relocate utilities, structures, etc., doing so was always shelved — until 2017 when it was finally green-lighted.

All Pans on Deck
The interchange project is divided into six separate phases, the first four of which have been awarded to JJA as the lowest bidder. The centerpiece of the current phase, named GR-4, includes the reconstruction and widening of a 6,900 ft. viaduct that carries northbound and southbound I-95 as well as a series of on- and off-ramps. Concrete subcontractor, B. Pietrini & Sons (King of Prussia, Pa) used a number of pumps to pour the pan decks which ranged in size from 8.5” to 9.5” with thicknesses of about one foot at the girders. According to “Tank” Stolzfus, Pietrini’s operator, even on a project that was nearly a mile long, accessibility was often an issue.

“The viaduct is elevated ranging from 15’ to 40’ or so and everything was pumped from below,” he said. “That meant dealing with whatever was adjacent to the pour area at the time. In one segment where we were using our S 58 SX pump, we had to get the boom up between the bridge and an on-ramp to pour. To make that happen, however, it was obvious we needed to short-rig the unit. Fortunately for us, that 58-meter pump features Schwing’s EASy Flex system and we were able to safely short-rig the outriggers when needed. That made all the difference and kept us on track.”

Integrated into Schwing’s VECTOR Controls, the EASy system ensures the safety of the pump and its operator by monitoring the location of the outriggers and position of the boom sections.

The project had no shortage of inherent challenges. For example, the original interchange, which was demoed as part of the GR-3 phase, was built extremely close to existing commercial buildings. So, in order to accommodate the updated design with its added lanes and new exits, a surface street needed to be moved and the new interchange was pushed 50’ to the east.

Unfolding Situation
With GR-4 in full swing, Pietrini & Sons had the opportunity to draw upon every pump at its disposal — they own more than a dozen boom pumps alone — but focused on a newly-purchased Schwing S 47 SX III. According to Stolzfus, it was the unit’s five-section boom that drove that decision.

“The five-section design was key for us because of the elevated nature of the decks,” he said. “When we were setting up, because of that initial height above ground, we would have lost considerable reach with a four-section boom. One full section would be taken with the vertical, leaving us with only three sections to reach across the deck. Instead, we were able to use the first section for the lift we needed and still have four sections remaining for reach — that bailed us out on more than one occasion.”

It’s important to note that the GR-4 project was more than a simple bridge rehab. The amount of advance work needed to make the project ready was impressive by itself, since five major sewers that run under the site had to be protected, as did lines for water, electric, communications, etc.

“And, because this Mid-Atlantic region sits on a major fault line, there was also a need for seismic upgrades,” said JJA’s Smith. “The problem with older structures is that, even if they’re not failing, they don’t meet the seismic requirements, so they can’t be renovated. As a result, everything from the ground up is brand new: pilings, foundations, and so on. There are 54 new pier footings, each of which had 4 to 6 columns on it and was newly-capped. Though some of that activity was pumped, a good deal was crane and bucketed simply because of crane availability.”

Sign of the Times
Access and clearance seems to be the order of the day for the GR-4 project. Faced with several situations in which both were in short supply Pietrini’s reliance upon the 47-meter pump seemed downright prescient.

“In addition to the situation mentioned earlier, there were a number of other times when things were so tight we’ve had to short-rig out there,” said Stolzfus. “For example, at one point, we were working in an area adjacent to a billboard. While the sign itself was at road height, the podium extended downward right into the area where we needed to set up. We once again drew upon the unit’s EASy Flex system which allowed us to set up tight to the base without fully extending the weak side outriggers, then safely pump up and over the sign.”

Because the interchange viaduct extends for nearly a mile, there were also times when logistics dictated that Pietrini pump literally from under the bridge. In those cases, said Stolzfus, they got creative but, once again, benefited from the five-section design of the 47-meter pump.

“On several pours, we had three-quarters of the pump under the bridge, with the turret just barely extending out from underneath,” he said. “In order to unfold, we had to pick the boom out of the cradle a bit and then swing all the way to one side before we could begin to unfold. You really don’t realize it until you have it, but that fifth section truly can make all the difference.”

Getting Specific
Staying with an updated version of the original method of construction, engineers on the GR-4 project spec’d both steel plate and Bulb-Tee girders. The latter is a long-span concrete girder that incorporates the benefits of both an I-beam design and a precast slab deck. Rebar, more than 5,500 tons of it, was heavy throughout the project, ranging in size from #4 to #18 bar. Concrete for the decks, supplied by SJA Construction, Inc., featured a 4,000 psi mix design (AAAP) with a 5-inch slump.

Stolzfus said the fact that they were pumping a PenDOT mix immediately got his attention. “I always joke that PenDOT mixes are so heavy in aggregate that if there is one extra stone in a 10-yard truck it might not be pumpable. But we’ve had no problems.”

Smith added that the AAAP design utilized a plasticizer both to retard the setting and reduce the risk of cracking

“There were hundreds of unique pours on this entire job, he said. “Deck pours were done in segments, with the average segment involving a pour of between 350 and 450 yards. Between SJA’s satellite plant, located directly across from the GR-4 project and the main plant south of the city, they probably ran 30 trucks for this phase of the job. I’m extremely proud of our people — we have some of the best in the business — and we’ve kept Pietrini busy since they came on board at the end of GR-3.”

He adds that their relationship with Pietrini and Sons — and Stolzfus in particular — has been great as well.

“The fact that we have such a good relationship with Pietrini is important. There are a lot of tough setups here, given the power lines, adjacent buildings, underground utilities, and so on. This project is not in a cornfield; anywhere you walk on this job, you are over a sewer, a duct bank, a gas main — you need a concrete team who understands and appreciates that. We also have a great safety record to maintain, no small feat considering we have 100+ people on site every day, counting subcontractors. So, care has to be taken with every setup and they give us that day after day. Through both their operators and their equipment, they’ve been a great partner to work with.”

The GIrard Avenue Interchange project, which has been slightly delayed by the COVID-19 pandemic, is now slated for a 2022 completion.

SPECS:

Owners: Pennsylvania Department of Transportation.
General Contractor: James J. Anderson Construction Co., Inc, Philadelphia, Pa.
Designers: (Prime) AECOM Consulting Engineers, Conshohocken, Pa.; (Sub Designers) Gannett Fleming, Inc., Valley Forge, Pa. & Dawood Engineering, Inc., Enola, Pa.,
Pumping Contractor: B. Pietrini & Sons Concrete Pumping, King of Prussia, Pa.
Concrete Supplier: SJA Construction, Philadelphia, Pa.
Equipment: Schwing S 39 SX, S47 SX III, and S 58 SX truck-mounted concrete pumps with placing boom.