Accelerated Bridge Construction( ABC)

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CHAPTER -1
INTRODUCTION
1.1 GENERAL
Bridges have always been an important part of our society, essential and vital
aspect for our day-to-day commuting. In transportation engineering, researchers and
engineers have been developing different technologies and innovating different
construction methods throughout the year in order to attain an economical, safe and more
convenient result in construction projects. There are many deficient bridges in the united
states ,and fixing them may cause many issues such as increasing the traffic congestion.
Therefore, accelerated bridge construction, or ABC, might be the best solution for bridge
replacement/rehabilitation because it save time. The accelerated bridge construction approach
is one of the latest construction approaches that has been developed. In fact ,prefabricating
bridge element offers major time saving cost saving , safety advantages and
convenience for travellers. The use of prefabricated bridge element is also solving many
construction challenges while enhancing bridge construction .further ,over the past
decade, the use of ABC has increasingly gained attention in the construction industry.
This unique bridge construction technique has construction time, decrease accident and
improve safety. On the other side of the coin, however ,the conventional bridge construction
method or CBC ,could be more beneficial ,regardless of all the benefits that comes with
new innovative method .
ABC is bridge construction that uses innovative planning ,design, material, and
construction methods in a safe and cost effective manner to reduce the onsite
construction time that occurs when building new bridges or replacing and rehabiliting
existing bridges .
At the beginning of the twenty - first century , It was noticeable that the use of the
precast modular construction for ABC has to started to gain popularity in the
construction industry . unlike the conventional construction method ,This distinctive
method seeks reduce construction duration and the impacts on traffic byrapidly building
bridges by building major bridge components close to their actual location and
installing them speedily by utilizing heavy lifting equipment such as cranes or self-
propelled transporters .ABC methods can greatly reduce the impact of construction

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work on both the environment and the community by working on the bridge`s
components away from the roadway .
ABC improves:
o Site constructability
o Total project delivery time
o Material quality and product durability
o Work – zone safety for the travelling and contractor personnel
ABC reduces :
o Traffic impacts
o Onsite construction time
o Weather - related time delays
ABC can minimize
o Environmental impacts
o Impacts to existing roadway alignment
o Utility relocations and right- of –way take
1.2 CONVENTIONAL BRIDGE CONSTRUCTION :
Conventional bridge construction is bridge construction that does not significantly
Reduce the onsite construction time that is needed to build, replace , or rehabilitate a
single, or group of bridge projects. Conventional construction methods involve onsite
activities that are time consuming and weather dependent .
An example of conventional construction includes onsite installation of substructure
and superstructure forms , followed by reinforcing steel placement, concrete placement,
and concrete curing, all typical occurring in a sequential manner.
One of the reasons to minimize onsite construction activity is because the long term
presence of contractor related equipment ,labour , and staging areas can present driver
distractions and traffic disruptions that reduce the safety and mobility efficiencies of
the transportation network .

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Time metrics for ABC :
To guage the effectiveness of ABC , two time matrics are used :
Onsite construction time :
The period of time from when a contactor alters the project site location until all
construction related activities is removed . This include, but is not limited to, the
removal of maintenance of traffic items , costruction materials, equipment, and personel
Mobility impact time :
Any period of time the traffic flow of the transportation network is reduced due to the
onsite construction activities
Tier 1: Traffic impacts within 1 to 24 hours
Tier 2: Traffic impacts within 3 days
Tier 3: Traffic impacts within 2 weeks
Tier 4: Traffic impacts within 3 months
Tier 5: Overall project schedule is significantly reduced by months to years
Data collection and analysis
Decision making :
The conventional bridge construction methods are still the most prominent process
used by the construction industry, and will take a long time for the ABC to be fully
adopted by state departments of transportation . The first step in conducting such
approach is to identify wheather ABC is suitable for a particular projects.
Decision – making flowchart :
The first approach , which is a quick and simple procedure , is to answer the questions
stated on the flowchart below, which was developed by the Federal highway
Administration. A set of decision – making criteria are used to assist decision select the
ideal method , whether ABC or CBC and also choose whether using a prefabricated
bridge is a more economical and effective choice or not .

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Figure 1.1 Decision – Making Flow Chart

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Chapter 2
ACCELERATED BRIDGE CONSTRUCTION
TECNOLOGIES
This chapter will focus on the various technologies that are employed for
ABC projects, the process and provisions, and how they are applicable to various
types of bridge construction projects. Below figure show the most common forms of
ABC technologies in use today as compiled by the Federal Highway Administration
as part of the “Every day counts” initiative. This effort is being used to encourage
innovation in construction in order to reduce impacts to the travelling public .
Figure 2.1 Accelerated bridge construction technologies
2.1 FOUNDATION AND WALL ELEMENT
2.1.1 Continuos flight auger piles (CFA)
This is method of constructing a deep foundation element using a simplified
continuous process. CFA piles are sometimes referred to as Augered cast in place
(ACIP) piles, drilled displacement piles , and screw piles .
Normally drill shafts require several distinct process. First, the shaft is drilled using
an auger or rock coring device . The materials within the pile bore hole are removed.
following this, reinforcement is placed in the hole and voids are filled with concrete.

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Continous flight auger piles methods combine several of these processes into
essentially one process. Figure 2.2 depicts a graphical representation of a CFA pile
installation. In process “a” ,a soil auger is drilled into the ground in a continuous
stroke. Once the proper depth is achieved , the auger is withdrawn from the soil in the
hole , while continuously injecting concrete through the hollow stem of the auger.this
process is labelled “b” in the figure. Once the auger has been withdrawn frm the
hole, a reinforcing cage is inserted into the wet concrete to complete the installation .
this process is lebeled “c” in the figure.
Figure 2.2 cotinuous flight auger pile installation
By combining these processes , the time for foundation installation can be reduced .
2.1.2 Geosynthetic reinforced soil integrated bridge system (GRS/IBS)
This method of foundation installation involves combining the foundation, abutment
and approach embankment into one composite material. The structure below the
superstructure is comprised of multiple thin layers of soil and geosynthetic
reinforcement . The internal soil is retained at the face of the abutment with high
quality concrete block facing . The facing is not a structural element of the system. It
simply retains and prevents erosion of the soil near the face of the wall. The

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composite mass extends beyond the ends of the bridge superstructure and into the
embackment . This integration of the abutment with the superstructure and approach
allows the system to move and settle as one unit, therefore eliminating the problem
with differential settlement often leads to a bump at the end of the bridge .
The superstructure typically sits in top of the GRS fill without bearings . the
superstructure loads, rotations, and movements are carried directly by the GRS system.
The system can be used with precast butted box beams , precast slabs ,or with
conventional stringer deck system . With stringer bridges, a small footing combined
with an integral pour is used to seat the superstructure on the GRS embankment
figure 2.3 depicts a typical section of a GRS/IBS bridge abutment .
Fig 2.3 Typical section of a GRS/ IBS Bridge Abutment
The benefits of this system include :
 Low initial cost
 Low life cycle cost

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 Fast construction (under 30 days for most bridges )
 Minimal installation labour and equipment
 Eliminates the need for approach slabs
The limitation of this system include :
 Span lengths are currently limited to spans less than 140 feet (until more data
on longer span bridges is compiled )
 The system is not appropriate for locations where scour would prevent the use
of shallow foundations
 It is currently only recommended for single span bridges, however multispan
bridges are being considered .
2.1.3 prefabricated pier cofferdams :
Construction of deep foundations in deep water is a daunting challenge . several
methods have been developed for cofferdams including driven steel sheeting and
framing systems combined with underwater tremie concrete . The advent of large
diameter piles and drilled shafts has reduced the need for deep concrete pours that
were traditionally placed below the mud line. Today, it is becoming more common to
perch the bottom of the pile cap footing just below the water surface.
Prefabrication can be used to facilitate the casting of the file cap footing. Pier box
forms have been developed that can be floated into position and hung from the piles
or drilled shafts . In some cases, the forms can be ballasted into position using
buoyancy to support the wet concrete. The pier boxes can preefabricated with steel and
removed after casting , or be fabricated with steel and removal after casting ,or be
fabricated with precast concrete and left in place .
2.2 RAPID EMBANKMENT CONTRUCTION :
2.2.1 Expanded polystyrene (EPS) geofoam :
EPS geofoam is an embankment fill system that is comprised of large blocks of
expanded polystyrene. Unlike the GRS/IBS system, it is not intended to be a structural
support system for the bridge abutment. The EPS blocks can be placed behind a
conventional abutment or around the pils of an integral abutment.

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Figure 2.4 is a photograph of a typical EPS geofoam embankment prior to placement
of the roadway structure and side slopes.
The benefits of this system include:
 Fast construction
 Extremely lightweight (1-2 pounds per cubic foot)
 Eliminates or reduces pre-load settlement times
The design considerations for this system incude:
 A layer of subbase is required below the pavement to distribute wheel loads.
 Protection of the foam blocks from gasoline spills.
 The system should not be used where the water table will be above the
bottom of the EPC blocks, which would cause uplifts forces.
Figure 2.4 EPS Geofoam Embankment
The lightweight nature of this material makes it ideal for areas where long term
settlement potential is high . The embankment weight can be reduced by a factor of up
to 100,which will greatly embankment pre-load time. More information on the subject
can be obtained at the FHWA website.

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2.2.2. Accelerated Embankment Preload Techniques:
Establishment of embankments over soils that are subjected to long-term settlement
such as clays can lead to a long -term construction process . often, preloads are
applied to the embankments to accelerate the settlement of the sub-soils prior to
roadway construction . Preload areas are often required to be left in place for many
moths and in some cases more than a year.
Technologies are available to accelerate the settlement of the sub-soils. The goal of a
preload system is to remove water from underlying clays in order to consolidate the
layers. Stone columns and wick drains have been used to accelerate the removal of
the water . This approach can reduce pre-load times by a factor of four or more.
2.2.3. Column Supported Embankment Techniques :
Another method of constructing embankments over compressible soils is to build a
soil structure over the existing compressible subsoils. This can involve the installation
of closely spaced piles or stone columns that are installed through the compressible
soils. Once in place, multiple layers of geosynthetic reinforced soils can be placed
over the columns to produce a structural soil layer that can be used to support the
new embankment . This method eliminates the need for time consuming pre-load of
compressible soils.
2.3 PREFABRICATED BRIDGE ELEMENTS AND SYSTEM
2.3.1 Prefabricated Elements :
The most common form of ABC is the use of prefabricated bridge elements .
These elements can be fabricated in a controlled environment off site and assembled
in place at the bridge site and assembled in place at the bridge site . This
construction method can be described as building blocks. The prefabricated elements
are connected at the site to form a complete bridge .
Prefabricaton of beams is not a new concept. Virtually all bridges are
currently built with prefabrication beams and girders. Other industries have used
prefabrication to speed project delivery and with lesser cost. Industries such as parking
structure have taken prefabrication to the highest levels . The newer concepts that are

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now finding more widespread use are prefabrication of the other prefabrication of the
other elements on a typically bridge,such as bridge decks and prefabricated
substructure elements ( including pier columns footing, and abutment/retaining wall
stems and footing) . Installation of prefabricated elements is normally completed using
standard cranes.
Fig 2.5. Conventional Bridge Construction
Fig 2.6. Accelerated Bridge Construction

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The FHWA manual entitled “connection details for prefabricated bridge elements and
systems ” contains significant information for various prefabricated element connections.
The durability of these connections has also been proven.For example : precast bridge
deck panels that have been in service in a nortern America environment for over 20
years and precast bridge piers that have been in service in a highly corrosive
environment for over 15 years. Chapter 3 includes more information on the
prefabricated elements.
2.3.2. Prefabricated systems :
It is possible to fabricate larger portions of the bridge and move them into place at a
later date. Examples of prefabricated systems include complete superstructure,
superstructures with integral piers, or even complete bridges .most work completed to
date in the United states has been with prefabricated superstructures although
engineers are starting to investigate work completed in Europe that also include
integral prefabricated substructure .A key component to large-scale prefabrication is
the methods used to move and install the elements. Typical crane installations are not
normally used due to the weight of the systems .The following section describes
methods used to install prefabricated systems.
2.4. STRUCTURAL PLACEMENT METHODS
There are various methods used to assemble the prefabricated elements of a bridge,
depending upon its location and structure system .However ,the most common methods
used for ABC are
A. Self Propelled Modular Transporters(SPMTs)
B. Longitudinal launching
C. Horizontal skidding or sliding
D. Other heavy lifting equipment and methods
E. Conventional cranes
Chapter 5 includes more information on installation of prefabricated elements

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Chapter 3
PREFABRICATED BRIDGE ELEMENTS
3.1. MATERIALS :
This section provides an overview of the many different types of materials used in
prefabrication and discuss the impact of the materials on accelerated construction
processes. Most agencies have approval processes for prequalification of proprietary
materials ( i.e. grouts, mechanical connector , etc.). Designers should be aware of the
materials that are available for use in a particular agency prior to specifying the
material.
3.1.1. Structural steel :
Steel elements are well suited for prefabrication and accelerated construction . there is
a high degree of control over fabrication tolerances ; therefore, complex connections
can be employed using structural steel. Common elements include steel beams and
girders, steel grid decks(including concrete filled and exodermic grid decks), and steel
railings . Other less common applications include steel pier columns, pier bents and
cellular sheet piling abutments.
One advantage that steel has over precast concrete is that it typically weighs less
than an equivalent concrete element. This factor can be critical when considering
shipping, crane capacitites, and SPMT capacities .
3.1.2. concrete (normal weight and light weight) :
Concrete is a popular and versatile material for prefabrication and ABC projects. The
ability t build elements off site in virtually any shape makes tis material a prime
choice for designers. Common prefabricated concrete elements include beams and
girders, full depth deck panels, and pier caps. pier columns, abutment stems , footings,
and retaining walls.

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System Concrete can also be used for making connections between different
prefabricated bridge elements. These connections often require the use of highly early
strength concrete to allow for accelerated construction processes.
3.1.3. Grouts
Many of the concrete elements are joined with grout. The connection between precast
concrete elements require the use of grout to fill the void between the ajoining
elements . Nominal width joints are required for several reasons . The primary reasons
are to allow for element tolerances and to make adjustments in the field.
Non –shrink cementitious grout is most often used to easily and efficiently provide a
durable, stable, structurally stable connection between precast concrete elements. Epoxy
joints can be used; however, they tend to have a low modulus of elasticity and are
expensive when compared to cementitious grouts. In order to achieve desired results,
careful selection and specification is required when using non –shrink grouts.
3.1.3.1. Grout Types:
Ideally a non –shrink cementitious grout will not exhibit dimensional change in the
plastic or hardened state . To achieve non –shrink characteristics in grout, additives are
mixed into the grout to counteract the natural tendency of grout to shrink. There are
different types of additives for cementitious grouts in the market. Several common
additives are as follows:
i. Gas Generaing :
A chemical substance is added to the grout mixture to control shrinkage.In
most cases , an aluminium powder is used.
ii. Ettringite :
Ettringite expansive grout relies on the growth of ettringite crystals during the
hardened state to counteract shrinkage.
iii. Air release:
Air release grouts do not rely on a chemical rection to achieve expansion. The
additive reacts with water to release expansion . The additive reacts with water
to release air and cause expansion.

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3.1.4. Ultra High Performance Concrete (UHPC) :
A new generation of high performance concrete has emerged in the ABC market. The
material is referred to as Ultra High Performance Concrete (UHPC) or as reactive
powder concrete. This proprietary product combines high quality cement and stone
products along with either steel or organic fibers. The material can achieve very high
compressive strengths of 18000 to 33000 psi. Another key feature of the material is
that it can also achieve very high flexural strengths of between 900 and 7000 psi
depending on the type of fibre used . This leads to a material that is very ductile.
UHPC also has very low permeability, which should lead to long service life. The
unit price for the material is much higher than conventional high performance
concrete. Even with its high cost, UHPC has a high potential for use in ABC. The
high compressive and tensile strength makes the product ideal for closure pour
connections between adjacent elements . On-going testing at FHWA has shown that
UHPC can develop reinforcing bars in very small distances . This opens up the
potential to have very small closure pours that are fully reinforced. This is perhaps
the best use of UHPC
UHPC is being investigated for the closure pour connection. The benefit of this types
of connection is that it will provide enough moment capacity to make the beam act
as a unit. This will allow the use of a live load distribution factor for bridge cross
section
Figure 3.1. Potential UPHC Connection for the NEXT Beam

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3.2. SUPERSTRUCTURE ELEMENTS :
Superstructures are defined by AASHTO as “Structural parts of the bridge that
provide the horizontal span ” For conventional bridges, the superstructure is often
defined as the portion of the bridge above the bridge bearings. The following sections
contain information on typical superstructure elements and system used for ABC. These
systems include decks, stringers/ beams, and large modular systems.
3.2.1. Beams and Girders :
Prefabrication of beams and girders has been an integral part of bridge construction
for many years . For this reason, this subject will not be covered in any great detail
in this report. The application of these systems to ABC will be presented here
instead.
3.2.1.1. Steel :
Welded steel girders can be configured in many ways to form a superstructure
framing system. Steel beams can be combined with a pre-topped concrete deck to
form modular superstructure units. These modular units have been used to allow the
replacement of superstructure in hours instead of months.
3.2.1.2. Precast/ prestressed concrete:
Precast concrete is one of the most common forms of prefabricated superstructure
girders . High performance concrete (HPC) has been introduced into the market to
improve the performance and durability of concrete girders. The use of more efficient
shapes such as bulb tee girders has become more common.
Adjacent butted precast girder systems such as double tees and deck bulb tees create
opportunities for ABC .These girders function as both the beam and the deck ,thereby
eliminating the need for deck placement in the field.
3.2.2. Prefabricated deck systems :
Deck systems are probably one of the most important elements of ABC . In fact, it is
very beneficial because in the conventional way of constructing a bridge, desk
erection can be time –consuming. While, on the other hand, when ABC is implemented,
the time that workers spend forming and placing concrete is no longer wasted. There

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are many types of prefab decks panels. However ,the two major types of precast deck
panels are the partial –depth and full –depth.
3.2.2.1. Full – depth Deck Panels :
In ABC, using the full depth panels can be greatly beneficial since it eliminates the
need of formwork, reinforcing steel placement, concrete placement, and curing. This
type of deck can be used in different size and shapes. Furthermore, these components
can be simply prestressed and are usually post-tensioning longitudinally after
placement since these components are pre-casted elsewhere.
A typical Full depth precast deck system that usually consists of precast concrete
panels as shown in below figure. There are various methods of connecting those
panels to each other. The most popular one is what`s called a “grouted shear
key”connection.
Figure 3.2. Full –depth Deck Panels
Figure 3.3. Grouted shear key

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3.2.2.2. Partial- Depth Panels :
This type of precast concrete panels, as shown in figure 16and 17, are thin prestressed
concrete panels that spread between girders and act as stay-in-place form for bridge
construction . These panels are usually 3.5 inches thick and eight feet long .
Figure 3.5. Typical Precast/ Prestressed Partial-Depth Deck Panel
Figure 3.6. Typical Partial –Depth Precast Panel Installation

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3.3. SUBSTRUCTURE ELEMENTS:
Substructure are defined by AASHO as the portion of the bridge between the
superstructure and the foundation. For conventional bridges, the substructure is normally
defined as the portion of the bridge below the bridge bearings and above the
footings. These includes piers, abutments , wingwalls and modular culvert/ arch systems .
3.3.1.Precast Concrete Pier System:
The precast pier system uses the collection of precast columns and the precast cap
beam elements to basically make piers, whether it is a single column or multiple
column type of piers. The single elements in the pier system are attached to the other
with mild reinforcing steel. Prefabricated pier elements have been used by many
country . This is due to the difficulty of forming and pouring concrete high above the
ground and the fact that that substructures offer opportunities for repetition . There can
also be significant savings by reducing construction time for substructure work over
bodies of water or near hazards such as railroads and power lines.
Figure 3.7 Single Column Pier Composed Of Precast Concrete Components

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3.3.1.1. Open Frame Bents:
Construction of open frame bents using cast-in-place concrete can be challenging. The
shoring and formwork system require to cast the concrete can be a significant
structure in itself. This is especially true for bent caps. Prefabrication of pier elements
Figure 3.8 Precast open Frame Pier Bent Sketch
Figure 3.9 Precast Pier Caps And Columns Built In Florida

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Figure 3. 9 shows a large bridge built in florida using precast pier caps and columns.
The connections were made using grouted sleeve reinforcing bar couplers.
Figure 3.10 Grouted Sleeve Reinforcing Bar Couplers
5.4 Foundations:
This section will describe in general the types of foundation elements that are
commonly used on ABC projects that involves new foundations. On some ABC
projects, such as superstructure replacement projects ,the foundation can be re-used. In
these cases the foundation Capacities should be investigated.
5.4.1.common Deep Foundations:
Most state agencies design bridges with deep foundations that are either supported on
driven piles, micropiles, continuous flight auger piles, or drilled shafts. Pile foundations
are normally capped with concrete footings in order to provide a stable platform to
support piers, walls and abutments . For short span bridges, thepiles bents can be used.
Pile bents are cost effective and can be built quickly since there is no need for a
footing. Most pile bents are constructed with precast concrete piles.

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Drilled shafts are becoming more popular. Large diameter drilled shafts can be used
to support individual concrete pier columns, thereby eliminating the need for a
concrete footing. And the ways to connect precast concrete pier columns to drilled
shafts. The method involves the use of non-contact lap splices in a small closure
pour at the base of the column. The column reinforcing is kept to a smaller diameter
than the shaft reinforcing thereby allowing the column reinforcing cage to be placed
within the top of the shaft reinforcing.
5.4.2 Prefabrication Foundation Elements:
5.4.2.1 Spread Footing :
Precast concrete spread footings are a relatively new concept in bridge construction.
The new Hampshire DOT developed a precast spread footing system for the Epping
Bridge project. These footings were placed over a prepared subgrade on levelling
bolts and then grouted into place. The joints between the footing elements are made
with shear keys that are filled with non-shrink grout.
The size of the footings for bridge piers can be quite large, which makes
transportation precast concrete footings difficult or even impossible. Figure 3.8 depicts
a four column pier bent. Four individual footings are shown . If a single continuous
footing was required, a single footing would be too large for shipping and handling.A
footing can be achieved by using precast concrete under the column only. These
smaller footings are designed to support the dead load of the bridge. Reinforcing bars
can be extended from the precast footings, and a cast-in-place closure pour can then
be completed during the erection of the remaining portions of the bridge. The
completed continuous footing is designed to support all other loads. The same
approach can be used for single column piers. Small footings can be placed under
the column and extended as the pier structure is being constructed.
5.4.2. pile cap footing:
Precast concrete can be used for concrete pile caps, Several stares have been used
grouted pockets to connect the piles to the cap . The FHWA conncetions manual
contains several details for pile cap connections.

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Recently, new details have been developed that make use of corrugated steel pipe
voids that are based on research that was completed in a lowa . This research showed
that a void made in a precast concrete footing with a corrugated steel pipe can be
provided very large punvhing shear resistance. Research on seismic connections has
also demonstrated that these voids can develop large moment resistance as well.
Below figure is a sketch of a precast concrete footing placed on precast concrete
piles. Corrugated steel pipe voids are used to make the connection between the piles
and the footing.
Figure 3.11 Precast Pile Cap Footing( with corrugated steel pipe void connection)
5.4.2.3. Precast Pier Box Cofferdams :
Several projects have bee designed where a precast concrete pier box was used to
dewater the area where the drilled shafts connects to the bridge footing.The precast
box was set over the drilled shaft and sealed with a small tremie pour around the
drilled shaft . These system can be eliminate the need for complicated cofferdams and
dewatering systems, especially in deep water . when built using HPC, the precast box
forms can serve as an additional corrosion protection system for the new pier footing.
The construction started with the installation of large pipe hanger clamps that were
hung from the pile casing , A steel alignment framing was then set on the clamps that
were hung from the pile casing , followed by the installation of precast floor and side

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panels. After that , the joints were grouted and a tremie pour installed, This system
gave the contractor a work space to set reinforcing and to pour the footing concrete.
The use of the precast concrete pier boxes saved the contractor many months of in
the construction of the foundations.
Figure 3.12 Construction of a Provision River Bridge
Figure 3.13 Details Of The Installation Of The Pier Box

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Figure 5.14 Precast Concrete Pier Box Cofferdam Installation

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CHAPTER 4
STRUCTURAL PLACEMENT METHODS
There are various methods used to assemble the prefabrication elements of a bridge,
depending upon its location and structural systems. However, the most common
methods used for ABC are “Lateral skidding/sliding” and “Self –propelled modular
Transporters(SPMTs )”.
4.1 HORIZONTAL SLIDING OR SKIDING:
When using this approach, a new superstructure is a built on a temporary support
alongside the old existing bridge . This technique allows the existing bridge to remain
in service without causing any traffic jam in the area while the one is being
constructed. This method can be executed in two stages. The first stage includes
building the substructure elements under the old existing bridge, as well as
constructing the superstructure on the temporary support beside the old bridge.
figure 4.1 First Stage Of Sliding Approach
The second stage requires closing the existing bridge in order to remove it, then
pushing the new bridge onto the support structures, and finally implementing the
needed pavement connections.

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Figure 4.2 Second Stage Of sliding Approach
SELF-PROPELLED MODULAR TRANSPOTTERS (SPMTs):
SPMT is a collection of multi-axel platforms that works through a computer controlled
system that can rotate 360 degree as needed that can be utilized to lift, transport, and
install the prefabricated bridges from an adjacent or off-site location to it final
location. In case of bridge replacement, SPMTs can be used to remove the existing
bridge.
figure
Figure 4.3 SPMT Bridge Moves in Utah
SPMTs are motorized vehicles that move at walking speed. Using this unique
technique can greatly reduce traffic disruption and improve work place overall safety.
A typical SPMT unit has a total of four or six axel lines with four to eight number
of tires per line. SPMTs can be pushed by an on-board hydraulic power pack, or it

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is called, “jack up system”, that is connected to the hydraulic drive motor an several
axes, its capacity, however, is approximately 40 tones/axle line. The most important
requirement to use this distinctive method is not only having skilled workers, but also
availability of location so it can be convenient to construct a bridge near location, it
also requires a feasible route from the off-site location to its final location.
4.3 LONGITUDINAL LAUNCHING:
Launching of superstructures has been used for many years for bridges over terrain
that is inaccessible for cranes. Longitudinal launching involves erection of the bridge
superstructure in a launching pit located behind one or both of the abutments. A
lightweight launching nose is often used to minimize the deflection of the cantilevered
end of the superstructure during the launching and to account for the defection of the
end of the bridge as it reaches each support. In some cases , intermediate towers are
used to minimize deflections on longer spans.
Launching can be relatively faster than other methods of construction at difficult sites;
therefore it warrants consideration.
Figure 4.4 Longitudinal Launching of a Utah Bridge

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4.4 OTHER HEAVY LIFTING EQUIPMENTS AND METHODS:
Large scale elements can also be installed using vertical lifting machinery. The most
common types of equipment are strand jacks and climbing jacks. The difference
between these two systems is that strands jacks pull the elements up vertically using
cables and the strands jacks pull the elements using hydraulics. These systems can lift
a large structures over waterway crossings where the structure can be shipped to the
site via barge.
4.5 Strand Jack Lifting of the Providence River Bridge
Another innovative erection methods have been developed to install prefabricated
elements on various bridges. gantry cranes are finding more use on ABC projects.
There are several configurations that have been used. The first is a transverse gantry
crane. Figure 4.6 is a sketch of a gantry crane supported on a temporary tresile. Once
installed, the crane can access all portions of the bridge site. During peak traffic
hours, the crane can be left in place, allowing traffic to pass beneath. This type of
system has been used on long span suspension bridge, where the gantry support rails
were placed on the fascia stiffening truss.

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Figure 4.6 Transverse Gantry Crane Installation Technique
4.5 CONVENTIONAL CRANES:
Many prefabrication elements can be installed using conventional cranes. Cranes are
an integral part of most bridge construction projects. The erection of beams and
girders are the primary use for cranes . It is possible in many cases to design
prefabricated elements to be approximately the same weight as the girders. In this
scenario, the same cranes can potentially be used for the erection of the
prefabrication elements and the girders.
Figure 4.7 Modular Element Installation Using Cranes

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CHAPTER 5
CONCLUSION
People involved in the transportation construction industry frequently seek safe,
economical , and durable construction methods. Being stuck in traffic, losing time ,gas,
money are all issues experienced daily by travellers during bridge rehabilitation
projects that cause disturbance. These issues, however, have becomes some of the
CBC method’s traits. The majority of bridge replacement projects are located in
heavy traffic areas , which often make it necessary to create detours or close bridges,
which could negatively impact the flow of vehicle , and effect the community and the
environment. Therefore ,one of the most common methods to accelerate bridge
construction projects is by utilizing prefabricated bridge components. These
components can be constructed off-site or close by the site before placing it to the
final bridge location. As a result, the traffic congestion will be greatly reduced, as well
as saving time and money. Time, cost, quality, and safety are four significant factors
in the planning , constructing , and controlling of any bridge project. Ultimately, when
owners have the financial capability as well as skilled workers to conduct bridge
replacement/rehabilitation projects in heavy traffic prone areas, using ABC would be
the best option . On the other hand, when owners do not have the financial capability
to pay extra cost for ABC,do not have skilled workers who are capable and highly
competent of doing the work, or when the location closure will not affect the traffic
flow, then using theCBC method would be the ideal approach to use for optimal
project success.

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REFERENCES
AASHO-AASHTO innovation initiative – Self Propelled Modular Transporters. Retrieved
may 22,2016 .
ABC- Accelerated- technologies and innovations- construction- federal Highway
Administration. Retrieved April 24,2016.
An inside look at designing for Accelerated Bridge Construction(ABC)-youtube.
Retrieved June 11,2016.
Federal Highway Administration. RetrievedMay 22,2016, from
http://www.fhwa.dot.gov/bridge/prefab/frameworkflowchart.cfm
International journal for Innovation Education and Research,www.ijier.net
Accelerated Bridge Construction – Experience in design, Fabrication and Erection of
Prefabricated bridge elements and system., Michael p. Culmo ,P.E .

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