January / February 2017

26

An RTG RM 20 pile-driving rig hammers battered piles in the shadows of a Penn-

sylvania Turnpike bridge abutment on a narrow strip of land between an embankment and a roadway on a warm October morning in 2016.

On driving an H-pile to refusal, the operator deftly executes a 180° turn within a confined space and crawls a short distance to retrieve the next sheet pile. A worker from PKF-Mark III hooks it up, the rig lures and secures it, and then travels back to the work site. The mechanical process repeats itself over and over.

The RM 20, preceded by the RG

19 T on the PA Turnpike/I-95 Interchange project, represents the willingness of the contractor to break with tradition to install bridge foundations. PKF histori-cally relied on a crane-suspended pile hammer. Its decision to rent pile-driving rigs from Equipment Corporation of America (ECA) is paying off.

CONNECTING THE MISSING LINK

Interstate 95 from Maine to Florida was completed in 1969 with no connection to the Pennsylvania Turnpike. Since that time, motor-ists have been forced to navigate crowded backroads to transfer between highways. The PA Turnpike/I-95 Interchange project – jointly owned by the Pennsylva-nia Turnpike Commission, Pennsyl-vania Department of Transporta-tion (PennDOT) and Federal Highway Administration (FHWA) – will create the missing link.

Newtown-based PKF has been ploughing through Section D10 since being awarded the US$142.9 million contract in August 2014. The firm is aiming to finish construction by October 2017. The contractor’s scope

includes reconstructing and widening 2.5 miles (4km) of the turnpike in Bucks County, building piers for the 14-span I-95 flyover ramp, replacing three mainline bridges, constructing a four-span bridge and repairing two bridges.

This project has special meaning to PKF as a local contractor, according to vice-president Larry Keough. “It’s one of those signature jobs we’ve been focused on for many years,” he says. “To have the privilege to be the first one out of the gate is pretty impressive.”

Piling superintendent Sabrina Villanti sits in a job trailer rattling off details on bridges as if she keeps a set of plans in her head. “All of our piling is in the main five bridges on this contract,” she explains over the muffled pound-ing of the RM 20 just outside.

This contract consists of several foundation elements, including 60,000 linear feet (18,288m) of H-piles, roughly 31,000ft2 of soil-nail wall earth support, 16,000ft2 of steel sheet pile earth support, and 6,000 linear feet of drilled shafts.

ABANDONING THE OLD METHOD

PKF has relied on a crane-sus-pended vibratory hammer with leaders since being founded in 1969. Breaking with tradition on a megaproject by switching to a pile-driving rig might seem risky, but PKF planned it carefully.

Keough clearly recalls the events leading up to the decision. The schedule dictated that PKF would need to run three pile-driv-ing operations concurrently. At the time, it was running two crawler cranes with vibratory hammers and the RG 19 T with a vibratory hammer. PKF considered renting a third crane and even purchased a second hammer.

“We were seeing productions that were leaving the crane-sus-pended vibratory hammer in the dust,” Villanti says of the RG 19 T. “We were doubling, if not tripling production, based on how many sheets we could drive in a day.”

PKF’s interest in the RM 20 had

PILING & FOUNDATIONS

Change of pacePKF’s bet on RTG pile-driving rigs pays off in the US, writes Brian M. Fraley

Below: PKF-

Mark III piling

superintendent

Sabrina Villanti

and ECA New

York/New Jersey

regional sales

manager Bruce

Langan worked

closely to keep

the RTG pile-

driving rigs

operating at peak

performance on

the PA

Turnpike/I-95

Interchange

project

PKF-Mark III

rented the RTG

RM 20 pile-

driving rig with

HRS 5 hydraulic

hammer in

August 2016 to

support several

foundation

elements,

including 60,000

linear feet of

H-piles

Visit us!

Silver Lots 1 & 2 –

S5420

March 7-11

BAUER Maschinen GmbH

BAUER-Strasse 1

86529 Schrobenhausen, Germany

www.bauer.de

BAUER Maschinen Group is the

world market leader in specialist

foundation engineering equipment

and in equipment for exploration,

development and exploitation of

natural resources.

PASSION FOR PROGRESS

January / February 2017

28 PILING & FOUNDATIONS

been piqued in winter 2015 during a demonstration at ECA’s Aldan, Pennsylvania, location. Although there was no need on the PA Turnpike/I-95 Interchange project at the time, ECA’s New York/New Jersey regional sales manager Bruce Langan arranged for the contractor to test the RM 20 on another project.

The RM 20 took centre stage in August 2016. PKF’s decision to scratch the itch and try out ECA’s RM 20 paid off. Its ability to double production allowed the contractor to eliminate the third set-up altogether. The contractor further capitalised by putting the unused second crane to work with a crew of carpenters.

PRODUCTION UP, LABOUR DOWN

The RM 20 also reduced man-power. The traditional set-up requires a crane operator sup-ported by a full crew of pile drivers, whereas the RM 20 requires an operator and a two-person crew.

The crew has adapted well with the RM 20 as the centrepiece of

the pile-driving operation. PKF has two operators, neither of which are piling rig operators.

The self-sufficiency of the RM 20 eliminated the need for one of the key foremen, according to Keough. “The RM 20 is so self-sufficient that you don’t need a key foreman,” he says. “You just need one person on the ground and another feeding the machine and that’s your crew.”

The primary operator boarded his first RTG pile-driving rig in summer 2015. ECA dispatched Langan and an ECA factory-trained service technician to the site at the outset to train the crew on the RM 20 and set the pace for a smooth transition.

“Given his experience with the previous machine [RG 19T], it only took him a couple of days to get acclimatised,” Keough recalls.

FEEDING THE BEAST

The onus to maintain a steady supply of piles was on PKF’s crew. Keough and the crew dubbed this process “feeding the beast”.

While the piles arrive on site marked with driving depths, they do not always match the supplied borings. It requires the team to choose and manage piles based on how the others are going in to avoid waste.

PKF was accustomed to being able to revisit driven piles before splicing because the hammer with leader dangles overhead and can be repositioned. Using a track-mounted machine such as the RTG required careful selection of pile sizes and immediate splicing in areas where driven piles were clustered several rows deep.

The RM 20 can effectively drive battered piles because of its adjustable leader, which can tilt backwards 45°, and forward and sideways 18.5°. The high turning point of the mast provides stability in even the most extreme inclinations.

Upon evaluating the positioning of the piers and abutments, in addition to the topography, PKF recognised that positioning the crane at street level to service the

pile-driving operation presented challenges. The RM 20’s ability to manoeuvre on the job site proved essential.

“The RM 20 is perfect for this project because you have high mobility in a confined area,” explains Dirk Himborg, sales director North America for Rammtechnik. “The rig has the option to be fitted with a hydrauli-cally driven mast foot and back jack-ups to facilitate lifting and rotation of the undercarriage, which is especially helpful on uneven surfaces and confined work spaces.”

HYDRAULIC HAMMER

PKF had been using the RG 19 T piling rig with a vibratory hammer in summer 2015 before the RM 20 with an HRS 5 accelerated hydraulic hammer took up a permanent position on the site. The RG 19 T was driving sheeting and soldier piles for non-loadbear-ing applications, but traffic was shifted onto newly constructed facilities in September 2016, prompting the need for a different approach.

“This is an accelerated hammer, so whatever position you have, you get a double push,” explains Himborg. “It gives the ram weight not only an up push, but also a push down, so you don’t lose any energy. You’re not relying strictly on gravity.”

The HRS 5 delivers up to 53,104ft lb (72,000Nm). PKF appreciated the ability to adjust the energy going into the hammer with the flick of a thumb.

The HRS 5 delivers a higher- percentage energy transfer than a traditional diesel hammer, and it is also faster, delivering 50 to 170 blows per minute.

The added power of the RM 20 with HRS 5 facilitated compliance with an aggressive PennDOT specification, which requires 20 blows per inch to refusal on bedrock. PKF was penetrating a silty sand surface, underlain by a tougher layer of saprolite, which varied in depth. PKF drove 14 x 89 H-piles to dense bedrock at 12ft

The RM 20 can

effectively drive

battered piles

because of its

adjustable

leader, which can

tilt backwards

45° and forward

and sideways

18.5°

29PILING & FOUNDATIONS

to 80ft, although 35ft was the average. Piles were capped with a heavy-duty steel tip for added penetration.

BETTER NEIGHBOUR

PKF was driving piles with ham-mers and leads from 7am to 10pm. Despite its respect for local noise

ordinances, Keough admits that some residents expressed concern.

“When we switched to the RM 20, there were no complaints even though we were closer to the neighbourhood,” he recalls. “You can stand 30ft away from that hammer [HRS 5] and not wear ear protection, whereas you couldn’t do that in the traditional setup.”

Langan adds: “There is a noise percussion system built into the hammer to eliminate the ring I call the ‘church bell sound’ when you hit steel on steel.” The HRS 5 contains a drive-cap system, a replaceable plastic insert that prevents steel on steel contact.

Keough says: “The one thing that we know after using the RG 19 T and the RM 20 is that given the right circumstances there’s no question we would purchase those units in lieu of the traditional crane, hammer and leads.”

And the opportunities are likely to increase. PKF, once focused only on foundation work on its heavy/highway construction projects throughout eastern Pennsylvania, New Jersey and northern Dela-ware, will now provide this work as subcontractor. Based on its successful switch on the PA Turnpike/I-95 Interchange project, the odds look good that the fleet will include RTG pile-driving rigs.

Brian M. Fraley is the owner of Fraley Construction Marketing

Main photo: PKF

drove 14 x 89

H-piles to dense

bedrock at 12ft

to 80ft, although

35ft was the

average

Inset: the HRS 5

accelerated

hydraulic

hammer

reportedly

delivered

a higher-

percentage

energy transfer

and greater

operating speed

than a traditional

diesel hammer