A SCRANTON GILLETTE COMMUNICATIONS PUBLICATION A ... · amount of time that we’ve done,”...
Transcript of A SCRANTON GILLETTE COMMUNICATIONS PUBLICATION A ... · amount of time that we’ve done,”...
A SCRANTON GILLETTE COMMUNICATIONS PUBLICATIONA SUPPLEMENT TO ROADS & BRIDGES
VIEWPOINT
It’s no secret these
are trying economic
times in which we
are now living. Many
people have called
this prolonged and
persistent reces-
sionary cycle the
worst economic cri-
sis since the Great
Depression. “Do
more with less” is the reality that we are all fac-
ing on a daily basis. Despite these sometimes
difficult current realities, it is important to guard
against the unintended consequence of pulling
in the reins so much that customers and suppli-
ers of products and services become isolated
and even polarized. Businesses need each
other in any industry community. No one does
business alone. A loss of institutional knowl-
edge and expertise, and even a breakdown
in the faith and confi dence that exists among
stakeholders, would take years to overcome.
There are no simple answers to these chal-
lenges, but we humbly offer three solutions that
we hope will preserve, and possibly strengthen,
your bottom line and your business relation-
ships while you navigate your way through
these times:
Keep the lines of communication open. Let’s •
face it, it is not just you. Everyone is busy
these days, and chances are they are not
only working hard at their jobs, but each per-
son also is carrying the extra weight of hav-
ing to tackle more issues. It is important to
stay in contact and to share information with
people who have similar interests and likely
are facing similar challenges. They may very
well provide the idea or solution you need.
Chances are they (and you) will benefi t from
a well-timed phone call, e-mail or visit, espe-
cially if that contact is aimed at some problem
solving;
Invest in continuing education and training. •
Often one of the fi rst business expenses
cut in tough times is employee training, but
this is a practice that defi nitely costs a busi-
ness more in the long run and may affect the
short term too. It is common experience that
well-trained employees improve a business’
efficiency and effectiveness. The benefi ts of
training may even be greater in tough times
when each decision carries more impact.
While no technology-based training can beat
forums where experts can personally transfer
the latest technology and share best prac-
tices, they can give your employees valuable
information at a fraction of the cost of tradi-
tional training courses. One- or two-hour we-
binar formats and self-directed online training
allow participants to fi t training into their busy
daily work requirements without the time or
expense of traveling to a training venue; and
Put your industry association to good use. •
As an association professional for more than
20 years, I realize that the value a business
derives from an association is in direct pro-
portion to its level of participation in the or-
ganization’s activities. Trade and professional
associations unite companies and organiza-
tions that have common interests and needs.
Especially now when the economic climate
limits business opportunities, we encourage
you to increase your involvement, not step
back. We encourage you to be well repre-
sented in actions that will directly infl uence
the paving materials, equipment, specifi ca-
tions, design requirements and construction
best practices that defi ne your opportunities
for new business.
No economic cycle lasts forever, and the
challenging times of today will give way to a
cycle of growth.
While we all anxiously await more signs of
recovery, let’s not forget that now, more than
ever before, we need each other in this industry
community. •
Voigt is president and chief executive offi cer of the American Concrete Pavement Association, Skokie, Ill.
Applying anecdotes could help you through the tough times
Turn three solutions
By Gerald F. Voigt, P.E.
A SCRANTON GILLETTE COMMUNICATIONS PUBLICATIONA SUPPLEMENT TO ROADS& BRIDGES
On the cover: Workers check progress during the con-struction of the Lewisville Lake Toll Bridge.
Features3 WITHOUT
THE RIPPLES Crews work
through chal-lenges on the lake with the right design, equipment
8 CONNECT FOURTH
A closer look at what went into the Illinois Toll-way’s extra lane on the Tri-State
11 FIXING AIR HOLES
Latest research presents method-ology to prevent climate change
15 FIXING FAULT Pavement resto-
ration helps cure faulted pavement on I-44
18 URBANOUTFITTING
Contractor speeds through heart of St. Louis behind design-build schedule
S2 / CONCRETE PROGRESS www.ROADSBRIDGES.com
CONCRETE PROGRESS / S3
Don Talend
LL ewisville Lake, a 23,280-acre lake located just
northwest of Dallas, is a favorite of area sailboaters
and fi shermen, but in recent years, it hasn’t done
much for drivers.
Two major north-south arterials that stretch north of Dallas,
I-35E and the Dallas North Tollway, straddle the lake and cur-
rently no east-west connecting route exists between the two.
Circumventing the lake to get from one arterial to the other
takes drivers half an hour or more.
Part of the solution to this problem will be a 2.03-mile-long
toll bridge which opened to vehicular traffic in August 2009.
Combine a high-profi le bridge project, a fast-track schedule
and a big lake, and the contractor needs the most high-tech
tools it can fi nd to survey the structure with pinpoint accuracy
amid strong wave action.
The North Texas Tollway Authority (NTTA) awarded Des
Moines, Iowa-based Jensen Construction Co. a $93 million
contract to erect a bridge over the lake. The company began
work on a 1,000-ft-long fl ow-easement bridge on the west side
of the lake in late 2006 and then started constructing the lake
bridge in February 2007. This contract is the centerpiece of
roughly $220 million in congestion-easing road improvements
to be made to a surrounding 13.7-mile corridor.
The center of the bridge has a tied-arch span that supports
the bridge deck with cable hangers. This segment also features
a 370-ft-long center span with the bents, i.e., piers, spaced to
allow plenty of room for boat traffic to pass under the bridge.
Two arch bents supporting the center span, combined with an
arched steel-truss structure, give the structure a distinctive ar-
chitectural appearance as the arch bents themselves resemble
sails. Adding to the nautical appearance of the structure are
four more pairs of “light bents,” which resemble lighthouses and
shine light to the north and south of the bridge.
The majority of the spans were designed to utilize pre-
stressed concrete beams, which have a typical length of 120 ft.
Bexar Concrete, San Antonio, precast the beams, deck panels
and skirt panels and trucked them to the jobsite. At a dock in
Lake Dallas on the west side of the lake, the precast elements
were unloaded onto barges, shipped and erected.
The time frame on Jensen’s contract was only 30 months,
meaning productivity was king. Ryan Cheeseman, P.E., the
project engineer for Jensen Construction, fully recognized that
Without theripplesCrews work through challenges on lake with the right design, equipment
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time was money on this project. “It’s the most work in the least
amount of time that we’ve done,” Cheeseman noted.
As a result of the tight schedule, Jensen Construction used
equipment and practices that increase construction efficiency as
much as possible while maintaining adherence to design toler-
ances. Two examples were the use of special light-bent and arch-
bent footing forms that also worked as temporary cofferdams,
and Global Navigation Satellite System (GNSS) receivers for sur-
veying most of the bridge substructure and superstructure.
The use of these items had gone a long way toward keeping
the project on schedule as of just before Memorial Day 2008,
when the building team reached the halfway point. The bridge
had remained on schedule to that point despite challenges
such as an unusually wet May in 2007 in which an 8.34-in.
rainfall total was recorded at Dallas/Fort Worth International
Airport. The area saw even more rainfall in June 2007: more
than 11 in.
Bent on footingsThe most unique design and construction aspects of the
Lewisville Lake Toll Bridge are the arch bents, light bents and
the footings supporting these bridge bents.
These bent footing forms also are temporary cofferdams.
While conventional cofferdams are constructed by driving
sheet piling into the bed of a body of water, building a seal
around the base of the sheet piling and pumping out the enclo-
sure, the footings on this project have replaced the sheet piling
with a concrete footing cast above the surface.
“Conventional cofferdams are very, very tedious and time
consuming and they cost a lot of money,” Cheeseman noted.
“With this type of footing, we were able to complete that whole
footing in about a week and a half, which kept things mov-
ing really quickly. It’s just like a temporary cofferdam using the
formwork of the footing as the cofferdam.”
Drilled-shaft casings—which are 60, 72, 84 or 96 in. in diam-
eter—were driven into the lake bed by ATS Drilling, Fort Worth,
Texas. A 1-ft-thick footing bottom slab was cast on a barge and
the footing forms were set on the bottom slab. The forms and
slab were then set on top of the drilled shafts and supported
by steel hangers welded to the drilled-shaft casing. Workers
pumped out water, installed the rebar and placed concrete for
the footing. Divers stripped the footing,
and skirt panels were hung on the sides
of the footing. Finally, a footing cap was
placed to get the footing to grade.
The arch bents are hollow and have a
thickness of 2 ft 6 in. Each bent required
fi ve concrete placements prior to con-
struction of the bent caps. A vertical sec-
tion facing the center of the lake was cast.
Then a sloped section facing the shore-
line was formed and cast. At the top of
these two sections, a slab was cast that
formed the fl oor of utility rooms. Another
vertical section that forms the utility room
walls was cast on top of the slab, and the
fi fth placement was the roof of the utility
rooms. The caps were then constructed on top of the bents
and supported the beam seats. All columns and caps on the
project were mass-concrete placements and required temper-
ature-controlled concrete. The concrete supplier, Dallas-based
TXI, used liquid nitrogen in the batching concrete to reduce
the heat of hydration in the cement paste—one of the most
extreme measures available for reducing concrete tempera-
ture in massive concrete structures. Temperature-monitoring
devices were being used to check core temperatures vs. ex-
ternal temperatures and safeguard against the potential for
structural cracking.
Teaming Russia with U.S.Jensen Construction used Topcon HiPer Lite+ GNSS re-
ceivers to survey the bridge substructure all the way up to the
beam seats. Cheeseman pointed out that GNSS was used
where possible to address productivity and logistical issues.
A Topcon GTS-235W total station was used for profi ling each
of the girders for setting the decking, he noted, and on the su-
perstructure, the total station was used for deck and paving
grades. In these areas, he explained, maximum pinpoint ac-
curacy was essential. Still, the GNSS equipment is normally
accurate to within roughly fi ve-eighths of an inch of target on
a typical day.
In recent years, surveyors have begun to rely on GNSS
equipment for more and more topographical surveying work
once control is defi ned on a work site. These systems use a
“rover”—a rugged GNSS receiver/antenna that the surveyor
moves from one location to another—and a base station, the
latter of which is located at a known stationary point on the site.
Satellites send positioning data to the base station and to the
rover. The stationary base and mobile rover work together to
provide accurate topographical data. Recently, these systems
have become even more reliable and accurate as they have
added compatibility with the Russian GLONASS satellite con-
stellation as well as the U.S. Global Positioning System satellite
constellation. This dual-constellation capability roughly doubles
the number of signals available to the GNSS antenna/receivers
and provides a high degree of positioning accuracy.
Working on water with strong winds and currents does make
the use of GNSS surveying equipment a benefi cial option
The most unique design and construction aspects of the Lewisville Lake Toll Bridge are the arch bents, light bents and the footings supporting these bridge bents.
CONCRETE PROGRESS / S7
where feasible, Cheeseman said. A professional surveying fi rm
was fi rst brought in to defi ne control, and as the fi rst footings
and bents were being constructed, Cheeseman and Jensen’s
surveying team had several “crow’s nests” constructed along
the shoreline. These used 24-in. pipe pile-driven into the lake
bed and small iron work platforms welded to the top of the pipe.
But the wave action on the lake caused slight movement of the
crow’s nests and compromised surveying accuracy.
“We used the crow’s nests just enough to get the control
traversed from one side to the other and got coordinates de-
fi ned, and from that point we just kind of abandoned them
because they weren’t doing us any good,” said Cheeseman.
“They moved so much with the wave action that we couldn’t
set up an instrument and be confi dent that every day we were
going to repeat our locations.”
Cheeseman, along with Jensen Construction surveyors
Laine Buller and Marcus Marion, had already spearheaded ef-
forts to start incorporating the use of GNSS surveying equip-
ment into the company’s bridge work. Before work began on
the Lewisville bridge project, Jensen Construction purchased
the HiPer Lite+ unit from Griner & Schmitz, a distributor of sur-
veying and construction equipment in Kansas City.
“From a productivity and constructability standpoint, we went
to the [GNSS] knowing we could get to within a tenth of a foot
or better every day, so we just ran with it,” Cheeseman said.
The total station maintained its place where ultra-pinpoint
accuracy was necessary on this project, but the location of the
GNSS receiver was less dependent on a level, stable surface
than the total station, so Jensen Construction’s surveying crew
could spend more time surveying from a wider range of loca-
tions without devoting as much time to equipment setup. Signal
reliability was not much of an issue on this project, Cheeseman
added. Noting that the receiver got signals from the base sta-
tion located on high ground all the way to the other side of the
lake—a distance of about 10,000 ft—he pointed out that signal
loss was rare.
The learning curve on the GNSS equipment was short,
the surveyors said. Terry Gammill, sales manager at Griner &
Schmitz, trained Jensen Construction’s surveying crew on the
equipment for a few days following delivery.
“We had a few issues a couple of times and Terry has dealt
with another one of our surveyor engineers and was extreme-
ly helpful,” said Buller, who has been a surveyor for about 10
years and joined Jensen Construction for her second stint at
the start of the Lewisville Lake Bridge project. “He could talk us
through how to fi x it over the phone and that helped a whole
bunch in the beginning.”
The technology was admittedly a bit intimidating at fi rst in that
the crew double-checked the accuracy of the readings with the
total station. As the total station verifi ed the accuracy of the GNSS
equipment, the confi dence grew. Buller noted that she checked
two control points every morning to ensure accurate references.
“We would go out on the lake and then when we came back,
we checked the point as we got on land every time just to make
sure it didn’t get switched around,” she added.
The leap in productivity from using the GNSS equipment
was noticeably signifi cant, Buller said. “I think it would have
taken two other surveyors” to maintain the level of productivity
that Jensen Construction enjoyed without the use of the equip-
ment, she said. “We love this [GNSS] because you carry it out
there and there’s no setting it up and going back to shoot your
backsight. It’s excellent, especially on this water.”
25,000 cars a dayThe structure is expected to handle 25,000 cars a day and
drastically reduce commute times for many. Drivers with elec-
tronic-collection-capable toll tags pay $1, and others pay $1.25.
Undoubtedly, many drivers will gladly pay tolls in exchange for
less “windshield time.” For example, the NTTA estimated that
the bridge will reduce the driving time from Lake Dallas, the
location of the overfl ow bridge on the lake’s west side, to Little
Elm on the east side from 45 to 10 minutes. Thanks to inno-
vation and technology, the Lewisville Lake Toll Bridge itself is
joining drivers on a fast track. •
Talend of Write Results, West Dundee, Ill., is a publicity and communica-tions project manager specializing in the construction industry.
LearnMore! For more information related to this article, go to:
www.roadsbridges.com/lm.cfm/rb110901
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Paul D. Kovacs and Steve Gillen
SS ince it fi rst opened in 1958, the Tri-State Tollway
(I-94/I-294/I-80) has stimulated economic growth
and development in the northern Illinois region.
But after nearly 50 years of service to ever-increas-
ing traffic, much of the Tri-State’s pavement was reaching the
end of its life cycle, and a major overhaul was needed to re-
duce congestion and improve service and road conditions for
tollway customers.
In 2004, the Illinois State Toll Highway Authority approved
a comprehensive $6.3 billion capital program including road
improvements on the North/Central Tri-State from Balmoral
Avenue near O’Hare International Airport to the Wisconsin
state line.
Budgeted at $1.3 billion, the North/Central Tri-State Rebuild
& Widen Project ranks as the largest construction project in
Illinois Tollway history.
CONNECTfourth
A closer look at what went into the Illinois Tollway’s
extra lane on the Tri-State
Heavily numberedThe entire 83-mile Tri-State Tollway func-
tions as a bypass around the metropolitan
Chicago area and serves as a commuter link
between Milwaukee and Chicago. Stretching
from just west of Indiana north to the Wiscon-
sin state line, it serves hundreds of thousands
of northern Illinois commuters, commercial
truck drivers and thousands more local busi-
nesses daily, as well as a multitude of visitors
who arrive in Chicago each day at O’Hare In-
ternational Airport.
Traffic in this corridor has grown dramatical-
ly in the past several decades, as more com-
mercial, residential and retail developments
have emerged. In 1959, there were an esti-
mated 43,000 vehicles a day traveling on the
Tri-State. In the 1970s, when a third lane was
added in each direction, average daily traffic
skyrocketed to about 275,000 vehicles a day.
Today, there are nearly 564,000 vehicles a day
traveling on the Tri-State Tollway.
To address current and future needs, the
scope of work on the North/Central Tri-State
Project included reconstructing and widening
to four lanes in each direction between Bal-
moral Avenue and Rte. 173 near the Wiscon-
sin border.
Work also included reconstructing the road-
way in the 2½-mile segment north of Rte. 173
to Russell Road and resurfacing pavement in the 1½-mile
stretch from Russell to the Wisconsin state line.
The project also widened and reconstructed nearly 60 bridg-
es, rebuilt about a dozen interchanges and reconstructed two
mainline toll plazas—all while maintaining efforts to minimize
disruptions to tollway customers.
Over the course of the project, the Tollway Authority recon-
structed more than 270 lane-miles of pavement, moved 8 mil-
lion cu yd of earth, used more than 1 million tons of steel and
poured more than 1.4 million cu yd of concrete. On any given
day, as many as 3,500 full- and part-time professional and con-
struction staff worked on this project.
What’s old is newThe original roadway was built with a 10-in. jointed reinforced
portland cement concrete (PCC) pavement, which was standard
at the time, and a porous granular material on top of a select
dense-graded aggregate sub-base. But higher-than-anticipated
traffic took its toll on the road, accelerating its deterioration over
time. And after three rehabilitation/overlay projects, it was time
for a complete reconstruction.
CONCRETE PROGRESS / S9
Plans for the rebuild and widen project entailed referencing
the American Association of State Highway & Transportation
Officials design guide in order to design the roadway in ac-
cordance with materials standards. Material specifi cations,
as well as quality control and quality assurance, were in line
with Illinois Department of Transportation (IDOT) standards for
pavement and any reinforcements.
From the start, the Tollway planned to recycle 100% of the
existing roadway concrete and asphalt during reconstruction
work. It also recycled concrete from the old Culligan Inter-
national Co. office building in Northbrook and miscellaneous
other sources as well. In total, the Tollway recycled nearly 1.6
million tons of concrete and asphalt as new pavement base ag-
gregates on the Tri-State Tollway, including more than an addi-
tional 200,000 tons of reclaimed asphalt pavement (RAP) from
other sources in the new hot-mix asphalt (HMA) mixtures used
for the HMA stabilized sub-base and new bituminous shoul-
ders of the Tri-State.
Reusing existing roadway materials was not only an envi-
ronmentally sensitive construction method, it also saved con-
tractors and the Tollway money in hauling fees and allowed
better quality control of materials. The extensive recycling ef-
forts required the contractors and the Tollway to apply extra
quality-control and quality-assurance practices to confi rm that
consistent and acceptable materials were being produced.
Work began in 2006, with the 3-in. HMA overlay being milled
off and stockpiled on-site to be used later in the stabilized sub-
base and HMA shoulders. Existing PCC was removed and
crushed, often onsite with portable crushers or mobile crush-
ers, for use as the porous granular embankment (PGE) base
for the new roadway. The existing or remaining base-course
aggregate was then classifi ed as an embankment material and
was removed or thickened to the proposed subgrade elevation.
In areas that did not meet compaction or proof-rolling require-
ments, the subgrade was undercut and backfi lled with extra
quantities of the recycled PGE aggregate.
The common use of mobile milling and crushing equipment
allowed for the recycled and reprocessed asphalt and concrete
materials to be windrowed along the reconstructed right-of-way
to reduce or eliminate the need for truck transportation.
The new roadway was built with a new 12-in. subgrade aggre-
gate consisting of 9 in. of PGE and 3 in. of capping aggregate
that consisted of RAP grindings of a CA-6 gradation placed on
the compacted subgrade/embankment. A 3-in. HMA-stabilized
sub-base was used on top of the 12-in. subgrade aggregate. A
12-in. jointed plain PCC pavement with 15-ft joint spacing was
then paved over the HMA-stabilized sub-base. The Tollway used
a standard IDOT Class PV concrete mix for all pavements.
Ultimate compressive strength was achieved in three to
four days, utilizing a liquid curing compound. The pavement
Circle 805
S10 / CONCRETE PROGRESS www.ROADSBRIDGES.com
was fi nished with variable-width tining slightly askew for bet-
ter control of tire noise. Pavement markings are recessed with
slow-cure multipolymer paint for improved refl ectivity and bet-
ter durability.
Double-lane slipform pavers, which measure 30 ft end to
end, were used for most of the mainline paving operations. Sin-
gle-lane slipform pavers were used mainly for paving ramps.
A standard paving train was used consisting of a spreader, a
paver and a tining machine.
Mainline shoulders were paved with bituminous asphalt uti-
lizing either a standard asphalt paver or a road widener. Both
machines used two rollers.
Work also included extensive amounts of noise wall and re-
construction of dozens of bridges. Bridge materials also fol-
lowed IDOT standards, pouring a 7½-in. concrete deck over
steel or precast prestressed concrete beams, with a seven-day
wet cure. Concrete conveyors or pumps were used to disperse
concrete onto the deck, followed by a bridge-deck fi nishing
machine. A series of work bridges were then used to apply
curing materials.
Trying not to disturbSome bridges, including Willow Road and Belvidere Road
(Illinois Rte. 120) also were lengthened to accommodate fu-
ture widening and reconstruction of local roads, and the Toll-
way worked closely with state and local agencies to develop
cost-sharing plans to minimize future traffic impacts.
As an example, the Willow Road Bridge was both lengthened
and widened to provide a six-lane pavement section with dual
left-turn lanes on Willow Road. This bridge expansion allowed
the reconstruction and widening of Willow Road from Sanders
Road to Landwehr Road, which not only helped reduce con-
gestion for the ramps to and from the Tri-State Tollway, but also
reduced travel times for local traffic.
Southbound construction was completed in 2008, and north-
bound work is expected to be completed by the end of 2009.
When construction began on the north end of the corridor in
2007, design engineers were busy at work designing plans for
2008 construction contracts. By performing construction while
designing work for the following year, the Tollway was able to
rebuild and widen the vast majority of the 45-mile stretch of
roadway in three years.
In order to rebuild and widen the roadway while maintaining
capacity, the Tollway adopted a maintenance of traffic (MOT)
plan that provided the same number of lanes during construc-
tion that were available before construction. As a result, lane
widths were reduced and traffic shifted into a counterfl ow con-
fi guration with express and local lanes. By shifting one lane
of traffic onto the other side of the road as an express lane,
the Tollway maintained three lanes of traffic during construc-
tion with work zones in place behind a temporary concrete
barrier wall.
The MOT plan reduced the impact of construction on drivers
while providing contractors the space they needed to work for
extended periods of time without frequent changes in the work
zone.
Additionally, the Tollway coordinated bridge reconstruction
by staggering construction schedules, thus providing alterna-
tive routes for the local drivers who relied upon the east-west
routes crossing over or under the Tri-State Tollway throughout
the region. Nearly all bridges were kept open during construc-
tion with staged traffic and reduced lanes. The Tollway coordi-
nated work with IDOT, Cook County, Lake County and local
government leaders to minimize the impact to local roads.
Farther to the north of the project, the Tollway continues to
work with the Wisconsin Department of Transportation on its
recently launched reconstruction plan for I-94 from Milwaukee
to the Illinois state line. In fact, the Tollway had extended its
widening project from Grand Avenue to Rte. 173 in part to coor-
dinate with Wisconsin’s I-94 reconstruction project. The Tollway
also is working with IDOT on its plans to widen the roadway
between Rte. 173 and the Wisconsin state line.
Kovacs is chief engineer and Gillen is materials manager at the Illinois Tollway, Downers Grove, Ill.
LearnMore! For more information related to this article, go to:
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Southbound construction on the Tri-State was completed in 2008, and northbound work is expected to be completed by the end of 2009.
CONCRETE PROGRESS / S11
Kamil Kaloush, Krishna P. Biligiri, Philip White and Jay Golden
TT he 21st century is the century of urbanization. Along
with rapid urbanization, the century is observing
the biggest increase in the world’s population in hu-
man history. As of 2006, the world population had
reached 6.5 billion. Urbanization is quickly transitioning com-
munities from native vegetation to an engineered infrastruc-
ture. The result is an increased thermal-storage capacity of the
urban infrastructure from the use of the materials. This regional
impact is known as the urban heat island effect where urban
temperatures are elevated in comparison with their adjacent
rural surroundings.
Rapid global urbanization and explosive overall population
increases are generating high demand for new road networks.
Paved surfaces can comprise up to 45% of an urban region
fabric in the U.S. and are designed with energy-intensive prod-
ucts composed of either portland cement or petroleum-based
asphalt. Both of these products contribute to greenhouse-gas
emissions and climate change at both the urban and global
scales. There is a need for quantifying the impacts of pavement
materials on climate change.
Climate change can be defi ned as the variation in meteo-
rological patterns that can range from a local to a much larger
multinational scale. The Intergovernmental Panel on Climate
Change (IPCC) developed the Global Warming Potential
(GWP) protocol to compare the ability of each greenhouse
gas to trap heat in the atmosphere relative to another gas. The
GWP of a greenhouse gas is defi ned as the ratio of the time-
integrated radiative forcing from the instantaneous release of
1 kg of a trace substance relative to that of 1 kg of a refer-
ence gas. Direct radiative effects occur when the gas itself is a
greenhouse gas. The reference gas used is CO2, and therefore
GWP-weighted emissions are measured in teragrams of CO2
equivalent (Tg CO2 Eq.).
The total U.S. emissions have risen by 16.3% from 1990
to 2005. In 2005, total U.S. greenhouse-gas emissions were
7,260.4 Tg CO2 Eq. Two of the top three categories for CO
2
emissions are related to pavements. This includes asphalt as
well as cement manufacturing.
This article is aimed at presenting a methodology for road
designers and transportation officials to model the impact of
Latest research presents
methodology to prevent climate change
FIXINGair holes
Figure 1. Major elements needed to model the annual CO2 Eq. per length of roadway section.
Layer Thickness of Different Materials in Pavement System Roadway Width
Roadway Service Life
kg CO2 Eq./kg ofMaterial Production
kg CO2 Eq./kg ofMaterial Mixing
kg CO2 Eq./kg ofMaterial Transportation
Total Annual CO 2 Equivalent per Lengthof Roadway Section
Density of Materials in a Pavement System
S12 / CONCRETE PROGRESS www.ROADSBRIDGES.com
different pavement types on climate change potentials in terms
of CO2-equivalent emissions. The process presented employs
variables that can be modifi ed by the designer to customize for
their specifi c road confi guration and materials type.
What’s the equivalent?Figure 1 shows some of the major elements needed to mod-
el the annual CO2 Eq. per length of roadway section. These
specifi c elements were selected because they provide a quan-
tifi able input to perform an analytical comparison. Other ele-
ments, such as rolling resistance, were found to be difficult and
challenging to consider in the modeling approach.
Table 1 provides a summary of components used to model
estimates of Kg CO2 Eq. produced per kilogram of the two
pavement types: portland cement concrete (PCC) and hot-mix
asphalt (HMA). The CO2 Eq. data came from high-quality in-
ventory output data of European origin. This data was used
because of its availability and considerable details. In addition,
it is noted that this assessment is limited to the fi rst life cycle of
the pavement. It does not take into consideration the resources
for emissions or lifetime created by secondary operations to
recycle the respective types of roads.
Figure 2 shows typical proportions of pavement materials
and their respective CO2 Eq. values per kg for production (Pn).
The transportation (Tp) values for these pavements, including
sand and gravel, are kept the same for simplicity. They were
calculated based on a 20-ton diesel truck (0.2821 Kg CO2 Eq. /
ton-km or 0.0002821 Kg CO2 Eq. / kg – km). Figure 3 shows the
mixing values (Mn), which were calculated utilizing CO2 Eq. for
the fuels utilized for each of the pavement structures. The CO2
Eq. impacts from mixing the concrete assume a 355-kilowatt
diesel truck running 36 minutes/batch, with 0.76 cu m/batch,
which is equivalent to 18,420 kg/batch. Based on interviews
Figure 3. Mixing values for PCC and HMA.
Figure 2. Kg CO2 Eq. values for the production of PCC and HMA.
GlobalWarming Gas
Portlandcement per Kg
Gravel per Kg Sand per Kg
Asphalt
Cement per Kg
Electricity,
US averagePer kW-hr
Transportper ton-km
Carbon dioxide, fossil 0.8048 0.0027 0.0023 0.3817 0.7155 0.2713
Carbon dioxide, fossil 0.0151 0.0001 0.0001 0.0410 0.0308 0.0084
Methane,fossil
0.0008 0 0 0.0010 0.0004 0.0011
Carbon monoxide, fossil
0 0 0 0.0023 0.0055 0.0012
Total Kg CO2 Eq. /kg
substance0.8207 0.0028 0.0025 0.4260 0.7468 0.2821
Table 1. A summary of components used to model estimates of Kg CO2 Eq. produced per kg of the two pavement types: portland cement concrete and hot-mix asphalt.
Figure 4. The total annual kg CO2 Eq./km with different pavement designs.
Total kg CO2 Eq./kg of Pavement Material during Production Process
Total kg CO2 Eq./kg of Pavement Material during Mixing Process
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0.07
0.06
0.05
0.04
0.03PCC, 0.0065
HMA, 0.0663
0.02
0.01
0.00
Gravel (PCC) Sand (PCC) Portland Cement (PCC) Aggregate (HMA) Asphalt Cement (HMA)
% weight
40% 39%
13%
95%
5%0.0011% 0.001%
0.1034%
0.0025% 0.0213%
Kg CO2 Eq./kg
Transportation kg An. CO2 Bq./km
HMA 4", Base 6"
3,722 4,268 3,232 2,526 3,956
11,210 13,079 1,161 4,124 7,732
4,517 5,242 19,105 7,951 14,620
HMA 7", Base 10" PCC 10", Base 8" UTW 2", HMA 2", Base 6”
TW 5", HMA 5", Base 8”
30,000
25,000
20,000
15,000
10,000
5,000
0
Mixing kg An. CO2 Eq./km
Production An. CO2 Eq./km
CONCRETE PROGRESS / S13
with regional companies, the process-
ing data for a 2-ton asphalt/hr-capac-
ity system was determined to require
24.6 L of No. 2 fuel oil and 0.269 cu m
of natural gas per hour. The electric-
ity process inventory data source is a
North American average.
Table 2 summarizes the density and
CO2 equivalents for the production,
transportation and mixing stages for
both pavement types.
Pavement changeClimate change values are modeled
with IPCC 2007 CO2 characterization
values. Five pavement design scenar-
ios are created as shown in Table 3.
Note that these pavement designs are
presented for demonstration purpos-
es, and obviously they are the user’s
specifi c input. The thicknesses were
selected to represent common designs
practiced by transportation agencies.
Two designs are designated with mod-
erate traffic volume, whereas the other
three were designated as high traffic
volume designs. The estimated life for
each pavement was selected based
on practical pavement performance
experience of the authors (again, this
is a user input). UTW is an ultrathin
whitetopping PCC pavement; whereas
TW is a thin whitetopping PCC pave-
ment design.
A functional unit of 1/km-year and
a damage score unit of kg CO2 Eq./
km-year are used. Pavement width is
assumed to be two 12-ft-wide lanes
for all case scenarios. The distance
from material production site to ap-
plication site (Di) for aggregates was
assumed to be 25 km. The distance
from material production site to place-
ment site (Di) for HMA or PCC was
assumed to be 50 km. The values of
total CO2/km were calculated for each
Circle 802
Pavement CO2
equivalency valuesDn
Kg / m3
PnKg CO
2 Eq./kg
Tp
Kg CO2 Eq./kg - km
Mn
Kg CO2 Eq./kg
Sand 1600 0.0028 0.0002821 0
Gravel 1800 0.0025 0.0002821 0
Aggregate 1700 0.0026 0.0002821 0
PCC 2403 0.1055 0.0002821 0.00650
HMA 2275 0.0238 0.0002821 0.06630
Table 2. Density and total CO2 equivalents for production, transport and the mixing of pavement.
Upper layer Middle layer Aggregate Base Traffic
volume
Estimated
Life, yearsType inch meter Type inch meter inch meter
HMA 4 0.1016 6 0.1524 moderate 10
HMA 7 0.1778 10 0.2540 high 15
PCC 10 0.2540 8 0.2032 high 25
UTW 2 0.0508 HMA 2 0.0508 6 0.2032 moderate 15
TW 5 0.1270 HMA 5 0.1270 8 0.2032 high 20
Table 3. Alternative pavement design case studies.
pavement layer individually, top surface layer, middle layer (if
any) and a bottom layer, which is normally an aggregate base.
Figure 4 presents the results for the fi ve pavement design sce-
narios. The results show that this approach provides a distinc-
tion of the total annual kg CO2 Eq. for each lifecycle component
and pavement structure type.
Climate designRapid urbanization will continue to place increased demands
for transportation infrastructure requiring additional pavement
construction. This article introduced a process on how pave-
ment construction contributes to climate change in terms of an-
nual kg CO2 Eq. emissions. The methodology should prove to
be a useful tool for engineers and planners to examine the di-
rect CO2 emissions related to the selection of alternative pave-
ment designs. By adjusting the model parameters, users can
optimize a pavement design based on organizational needs as
well as regionally different climatic conditions, traffic volumes,
road maintenance and energy needs. •
Kaloush is an associate professor, Department of Civil, Environmental and Sustainable Engineering and director of the National Center of Excellence for SMART Innovations at Arizona State University. Biligiri is a research scientist, Department of Civil, Environmental and Sustainable Engineering at ASU. White is an assistant professor, Industrial Design Unit, College of Design Innovation and Sustainability at ASU. Golden is an associate pro-fessor, School of Sustainability and co-director of the National Center for SMART Innovations at ASU.
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Kimberly Kaylor
WW hile much has been written about the use of
stimulus funds and the state of our nation’s in-
frastructure, one project that has been in the
works for years was recently completed, high-
lighting the effectiveness of the concrete pavement restoration
(CPR) process.
In August, the last 22.4-lane-mile section on I-44—a high-
way that runs from the southern border of Texas to the Mis-
souri border in the northeast corner of the state—was fi nally
completed. This is the rehabilitated area between I-40 and I-35
in Oklahoma City, located 0.6 miles north of Reno Avenue and
extending north 2.9 miles to 0.5 miles north of Northwest 36th
Street. It is the culmination of fi ve projects on the roadway since
repairs began in 2004. Penhall Co. (Division 40) has served as
the prime contractor for all fi ve projects.
The highway is signifi cant because it connects three of Okla-
homa’s largest cities and is a primary corridor through the Mid-
west. The Oklahoma City section of the highway ranges from six
to eight lanes and overlaps I-35 for a short time. Approximately
125,000 to 135,000 vehicles travel this roadway each day.
According to Tom Hubbard, P.E., resident engineer, Okla-
homa Department of Transportation (ODOT), a physical
survey revealed severe panel damage and faulted pavement.
The road was in desperate need of repair as the transverse
joint faulting was in the ¼-in. to 3⁄8-in. range with isolated ½-in.
to 5⁄8-in. faults and variable ¼-in. to ¾-in. faulting at the longitu-
dinal joints. Pavement replacement areas were quantifi ed us-
ing a vehicle-mounted digital image collection system.
Given the high level of traffic and poor road conditions, a
fast-track yet long-term solution was needed. As such, ODOT
selected CPR because of previous success with this method.
By selecting CPR, the state was able to extend the life of
existing pavement and minimize disruption to the traveling
public at a fraction of the cost of doing an asphalt overlay or
total reconstruction.
CPR is a nonoverlay option used to repair areas of distress
in concrete pavement without changing its grade. This pre-
ventive procedure restores the pavement to a like-new condi-
tion and reduces the need for major and more costly repairs.
Furthermore, CPR also addresses the causes of pavement
distress, minimizing further deterioration. In contrast, cov-
ering the area with an asphalt overlay does not correct the
cause, and the problem will eventually appear again, resulting
in a much more expensive solution. In fact, reports from the
Concrete pavement restoration helps cure faulted pavement on I-44
faultFixing
CONCRETE PROGRESS / S15
Transportation Research Board state that for every dollar in-
vested in appropriately timed preventive pavement mainte-
nance, $3 to $4 in future rehabilitation costs are saved.
Benefi ts of CPR include:
It addresses the causes of pavement distress, minimizing •
further deterioration;
It costs less and lasts longer. The California Department of •
Transportation (Caltrans) has shown that diamond grinding,
when used as a CPR strategy, typically lasts 16 to 17 years;
It is quicker and causes less traffic disruption. Because CPR •
maintains the existing grade, features such as curbs, gut-
ters, bridge clearances, approach slabs and roadside appur-
tenances do not need adjustment. In addition, CPR repairs
only those areas that need improvement, such as the driving
lane or the keel section of a runway;
It preserves the safety of concrete pavement. Concrete does •
not ravel, washboard or shove. These defects can cause seri-
ous safety problems for asphalt pavements at intersections or
other locations where traffic is starting, stopping and turning;
It preserves the environmental benefi ts of concrete pave-•
ment. Concrete’s light color reduces the number of street-
lights needed to achieve the same illumination on a dark as-
phalt pavement. The light surface also can keep urban areas
cool. Additionally, the hard concrete surface makes vehicles
more fuel efficient. Given the fact that concrete pavements do
not defl ect like asphalt pavements, studies have shown that
they can reduce truck fuel consumption signifi cantly; and
It can be used to repair a concrete pavement that has been •
previously overlaid with asphalt.
The tricky approachIn 2004, ODOT initiated repairs for all eastbound and west-
bound lanes, including auxiliary and ramp lanes, on I-44,
broken into the following fi ve phases:
In 2004, from the junction of S.H. 74 extending east to the •
Burlington Northern Santa Fe Railroad, just west of I-235;
In 2005, from west of Western Avenue, extending east to Lin-•
coln Blvd.;
In 2007, beginning at Lincoln Blvd., extending east to I-35; •
In 2008, beginning at the Oklahoma River, extending north •
to the Burlington Northern Santa Fe Bridge; and
In 2009, repair of four lanes, eastbound and westbound, be-•
ginning at the Burlington Northern Santa Fe Bridge to the
Junction of S.H. 74.
Dowel-bar retrofi t (DBR), diamond grinding, joint sealing,
selective panel replacement and base repair were used on
the project for all lanes in both directions. DBR restores load
transfer across the pavement joints to prevent future rough-
ness from occurring, and then the entire surface is diamond
ground, which produces a smooth and quiet ride. According to
Hubbard, DBR and diamond-grinding projects are extremely
effective in extending pavement service lives.
“In the past decade, many dowel-bar retrofi t and diamond-
grinding projects have been completed in the Oklahoma City
metro area. In each case, user costs were minimized by per-
forming the work during nighttime hours. The cost-effective na-
ture and minimized user costs are key in the success of pave-
ment restoration,” said Hubbard.
According to Mike Miller, the Penhall superintendent re-
sponsible for the bridge approach work, the 10th Street bridge
portion of the project, which consisted of 24 bridge approach
panels, presented many challenges. Specifi cally, it was diffi-
cult to remove the approach, perform subgrade repair, as well
as place the double-mat rebar reinforcement and high-early-
strength concrete during a single night shift during live traffic
even though it was diverted.
“Although we had done work like this before, we were very
concerned because we had never completed it in a single
night,” said Miller. “We used all the tools in our toolbox. We
had the best crew members, as well as extra equipment and
In 2004, ODOT initiated repairs for all eastbound and westbound lanes, including auxiliary and ramp lanes, on I-44. The work was broken down into fi ve phases and was com-pleted in 2009. The total value of this fi nal phase of the project was approximately $2.9 million, and the repair is expected to offer another 15 years of service life.
S16 / CONCRETE PROGRESS www.ROADSBRIDGES.com
materials staged in case we had any problems. The removal
went well, but we learned some lessons regarding the steel
placement. The key to our success was being able to batch
our own ready-mix. With the help of General Resource Tech-
nology, we were able to
manufacture and place
a high-strength con-
crete that kept us on
schedule.”
Safety also was a
daily concern. Accord-
ing to Miller, Action
Safety Supply did an
outstanding job mov-
ing the traveling public
though such a compli-
cated area. The com-
pany had crews on the
project during all hours
of the work. The work
area extended from
three to fi ve lanes with
right-hand and left-
hand on and off ramps.
“Action Safety Supply
played a critical part in
the success of the over-
all project,” said Miller.
Brent Burwell, execu-
tive director of the Okla-
homa/Arkansas Chapter of the American Concrete Pavement
Association, noted that it was excellent to see this section of
I-44 being restored using CPR instead of a costly asphalt over-
lay method.
“The original pavement, built in 1976, has served the public
well over the years, and with the improvements made to the
roadway through this project, we may see another decade or two
of service,” said Burwell. “The concrete pavement preservation
techniques used in this project do more than just cover the prob-
lem for a few years. Combined with the long life of the original
pavement, the work performed by the contractor, Penhall Co., will
give the taxpayers of Oklahoma a great value for their money.”
The total value of this fi nal phase of the project was approxi-
mately $2.9 million, and the repair is expected to offer another
15 years of service life. The total cost of all fi ve projects since
2004 was $11.3 million.
Pete Lewis, Penhall’s
regional manager re-
sponsible for its CPR
Division, said that his
fi rm has been involved
with the CPR industry
through its Highway
Services Division in
Rogers, Minn., for ap-
proximately 20 years.
He noted that they were
pleased when ODOT
started to ask ques-
tions regarding CPR.
“We are pleased to
have been a part of the
reconstruction of the
I-44 corridor in Okla-
homa City,” said Lewis.
“ODOT has always had
the best interest of the
traveling public and the
taxpayers of Oklahoma
in mind during this com-
plicated process. It was
with everyone’s hard work and honest considerations that CPR
had a chance to prove its value. CPR has proven that concrete
pavements are renewable.”
Kaylor is president of Constructive Communications Inc., Dublin, Ohio.
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CPR techniques include:Soil stabilization to support concrete slabs; •
Full-depth repairs that include removing a portion of the existing slab and replacing it with new concrete; •
Partial-depth repairs to correct surface distress and joint-crack deterioration in the upper third of the concrete slab; •
Dowel-bar retrofi t (DBR) that consists of cutting slots in the pavement across the joint or crack, cleaning the slots, placing • the dowel bars and backfi lling the slots with new concrete. This provides load transfer at the joints, allowing for a longer life for plain-jointed concrete pavements;
Cross-stitching longitudinal cracks or joints to add reinforcing steel to hold the crack together tightly; •
Diamond grinding, which removes faulting, slab warping, studded tire wear and unevenness resulting from patches. • Diamond grinding also reduces noise and provides proper skid numbers to ensure safe travel; and
Joint and crack resealing, which minimizes surface water and incompressible material infi ltration into the joint system, • minimizing long-term maintenance costs.
On the I-44 project user costs were minimized by performing the work during nighttime hours.The cost-effective nature and minimized user costs are key in the success of pavement restoration.
CONCRETE PROGRESS / S17
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AAunique project in Missouri is currently in its sec-
ond phase on I-64 through St. Louis. The design-
build project, the city’s fi rst, is a complete replace-
ment of approximately 10 miles of the interstate
right through the heart of the city. One-half of the 10 miles is
completely shut down to traffic while work takes place. The un-
precedented move is taking years off the completion date and
creating a safer environment for the construction workers.
The project is being built by a consortium called Gateway
Contractors, which involves contractors Granite Construction,
Fred Weber Inc. and Millstone Bangert Inc. The two-year proj-
ect involves 200,000 cu yd of concrete. All of the concrete will
be slipformed.
Fred Weber and Millstone Bangert have brought their fl eet of
equipment onto the project. That fl eet includes three GOMACO
9500 trimmer/placers, an RTP-500 placer, four Commander III
four-tracks and a GHP-2800 paver. It is a lot of equipment, but the
variety of applications the equipment is slipforming is impressive.
The Commander IIIs are slipforming shoulders, medians,
variable-width ramps, inside median barrier walls, outside bar-
rier walls, retaining walls, roundabouts, bridge parapets, truck
lanes, half-shaped barrier walls against mechanically stabilized
earth (MSE) walls and moment slabs for the sound wall.
10-12 on the smoothness scaleAll of the material on the project was recycled. The con-
crete was crushed and used again for the base material. The
base for the I-64 project consists of 10 in. of 6-in.-minus rock,
capped with 2 in. of Type 5 rock. The top layer is trimmed to the
accurate, fi nal grade with a GOMACO 9500 with an 18-ft-wide
trimmerhead.
Millstone Bangert is responsible for all of the mainline paving
on the project and is using its four-track GHP-2800 paver. Proj-
ect smoothness specifi cations require a reading of less than
30, and Millstone Bangert is consistently running between 10
and 12 on the zero-blanking band. Smoothness, according to
Ron Dibler, Millstone Bangert’s paving superintendent, begins
with the base.
“Good ride is a process that begins from the ground up,”
Dibler said. “You have to have good string, consistent mix and
try to keep the paver moving with minimum stops. Most impor-
tant, though, is a good, solid trimmed base to pave on and run
the paver’s tracks.”
Each paving pass is 9 or 10 in. thick and 25 ft wide. They are
building four new lanes of interstate for both the eastbound and
westbound sides. Paving production averages between 2,500
and 3,000 cu yd per day.
URBAN OUTFITTINGContractor speeds through heart of St. Louis behind design-build schedule
All of the concrete for the project is being supplied by two
onsite batch plants. Concrete is delivered to the paving site by
tandem-axle dump trucks. The concrete is a Missouri Depart-
ment of Transportation (MoDOT)-approved mix with an aver-
age slump of 1.5 in.
Putting up wallsThe profi les for the inside and outside barrier walls are very
similar, but the outside barrier has sound wall mounted to the
top of it. A Commander III is used to slipform a moment slab
with a rebar grid. The steel for the wall is tied to the rebar grid
in the moment slab. With the steel in place, the spacing for the
sound wall is meticulously plotted, and the anchoring bolts for
each post are carefully set.
“The sound wall posts have to be put in the exact location,
because each panel is made to fi t a certain area,” Dibler said.
“After the cages are built, we dry run the steel to make sure
everything is going to work and it’s all set to the right height.”
The concrete trucks dump their loads into an RTP-500,
which then feeds the belt on the Commander III. The cen-
tral mix concrete, according to Dibler, gives their concrete
more consistency and allows them to run a drier mix for their
barrier work.
Behind the Commander III, workers have to locate the an-
choring bolts for the sound wall, dig them out and expose them
so the posts can be installed after the concrete has cured.
A 9500 placer feeds another four-track Commander III as it
slipforms the variable-height center median barrier. The height
of the wall varies from 4 to 7.25 ft.
The non-variable-height barrier has 10 longitudinal bars fed
into the front of the mold for wall reinforcement. The variable-
height barrier is slipformed over a steel cage in the lower half
of the wall. They are inserting six longitudinal bars into the front
of the mold for the top section of the wall.
The consortium engineered a cost-saving measure on the
project by stacking two slipformed walls on top of each other
instead of putting in MSE wall. The fi rst retaining wall varies in
height between 3 and 6 ft. Two rebars are hydraulically inserted
vertically into the 24-in.-wide top of the wall, and vibration is
applied to the rebar during insertion. The wall is allowed to
cure and then backfi lled. The roadway is brought up to grade,
and then another section of wall is slipformed on top of the
existing wall.
“The slipformed retaining wall replaces MSE walls shorter
than 9 ft in areas that would retain dirt,” Dibler explained. “Rath-
er than building a costly MSE wall, we were able to slipform
retaining walls.”
All of the shoulders and medians on the project are slip-
formed with a side-mounted mold on the Commander III. Me-
dians are slipformed 6 ft wide. Shoulders vary from 4 to 10
ft, or 8.5 ft if there is a barrier wall on it. Zero-clearance pav-
ing against the MSE wall was accomplished after modifying
the mold.
“We had an idea of moving the sideform cylinders and
mounting structure from the outside of the mold to the inside of
the mold and minimizing the thickness of the sideform,” Dibler
said. “We were able to get that down to about 2 in., which
allows us to slipform closer to the walls, and that’s been a big
help on this job.”
Width changes on the ramps include transitions from 15 ft
down to 12 ft wide and 18 ft down to 12 ft wide. The transi-
tions are made on the go, with no need to stop and adjust the
paver width.
Another cost-saving measure on the project included build-
ing two roundabouts instead of entrance and exit ramps. The
20-ft-wide, 8-in.-thick roundabouts, with integral curb on one
side, had to be built around a 45-ft radius. Fred Weber decided
to pave the fi rst roundabout in two separate pours. The fi rst
was 10 ft wide and the second was the same width with a 3-in.
mountable curb.
“The tight radius intimidated us a bit on the fi rst roundabout,”
Jackson said. “The second one, though, we decided to pour
the full 20 ft with the curb on it. It worked out just fi ne, and we
accomplished it all in one pour, instead of two.”
To fi nish out the roundabout, a lane was slipformed inside
of its radius. The lane, which is used to assist trucks through
the roundabout, was 9 in. thick and 10 ft wide with a 6-in.
vertical curb.
The I-64 project is scheduled to have traffic back on the fi n-
ished second phase by the end of this year. It is a deadline the
consortium is confi dent they will make.
Information for this article provided by GOMACO Corp.
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CONCRETE PROGRESS / S19
Another cost-saving measure on the project included building two roundabouts instead of entrance and exit ramps. The 20-ft-wide, 8-in.-thick roundabouts, with integral curb on one side, had to be built around a 45-ft radius.
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