US-189 BRIDGE OVER THE DEER CREEK DAM
SPILLWAY IN PROVO CANYON
Dan Church, P.E.
Parsons Brinckerhoff
488 East Winchester Street
Suite 400
Murray, UT
Brendan Gill, P.E.
CH2M Hill
9191 South Jamaica Street
Englewood, CO 80112
Joe Showers, P.E.
CH2M Hill
9191 South Jamaica Street
Englewood, CO 80112
INTRODUCTION
The US-189 widening project in Provo Canyon, Utah included many engineering challenges to upgrade a
two lane highway to four lanes to improve safety along this stretch of highway from Wildwood to Deer
Creek State Park. The project includes split level alignments, rock cuts, an avalanche shed, and a bridge
in front of the Deer Creek Dam, spanning the spillway. The roadway alignment in front of the dam is
along a curved alignment, and the steel plate girder superstructure uses high performance steel, a first for
The Utah Department of Transportation (UDOT). The avalanche shed, located just east of the bridge, is
the first to be designed in the state of Utah, although the shed was excluded from the final contract
documents and will not be constructed at this time.
BRIDGE OVERVIEW
The Deer Creek Dam was constructed by the Bureau of Reclamation (BOR) between 1938 and 1941. It is
a zoned earth and rock-fill structure constructed to create the Deer Creek Reservoir and carries traffic
from US-189 across the dam. The new bridge will be located along the base of the embankment of the
dam. It will support two lanes of traffic in each direction with a center median. The alignment at this
Figure 1: Bridge Plan
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location is along an 835'-0" radius with the roadway super-elevated at 6% cross slope. The profile of the
roadway is approximately 100 feet above the base of the spillway. The bridge is in a sag vertical curve
The US-189 Bridge over the Dam Spillway is 515 feet long. It consists of three sp
with a maximum profile grade of 7.0%. Figure 1 includes the plan and elevation.
ans (145'-0" – 225'-0" –
AASHTO Standard Specifications for Bridge Design and
ach where NCHRP was found more conservative was use of a curved
steel cost and eliminate
n for the bridge
major issue. Large deck overhangs of 5'-
Figure 1: Bridge Elevation
145'-0"). The Bridge is 83'-2" wide and consists of 6 steel plate girders at 14'-6" spacing with 5'-4" deck
overhangs. The reinforced concrete deck is 10" thick. Figure 2 depicts the bridge cross section.
DESIGN CONSIDERATIONS
The bridge is designed according to
Construction, Sixteenth Edition and the AASHTO Guide Specifications for Horizontally Curved
Highway Bridges, 1993. At the time design commenced on the bridge, the AASHTO Guide
Specifications for Horizontally Curved Steel Girder Highway Bridges, 2003, was not available to be
considered part of the design criteria, however NCHRP Report 424, the basis for the new specification,
was available for reference. Where NCHRP Report 424 proved to be more conservative, the
recommendations were followed.
The most significant design appro
girder with a hybrid cross section. The 1993 Specifications would permit the design to allow the web to
yield, similar to design of a straight girder with a hybrid cross section. NCHRP Report 424 indicated that
sufficient research has not been completed and
documented showing this is acceptable. Future
research could suggest a curved girder with a
hybrid cross section could be utilized.
The entire steel superstructure is specified to
be AASHTO M270 Weathering Steel to
reduce the initial
future maintenance cost relating to painting
steel. The steel superstructure design
incorporated HPS Grade 70W steel in field
sections in negative moment regions and
Grade 50W steel in field sections for positive
moment regions. All cross frames, field splice
plates, and miscellaneous steel details use
Grade 50W weathering steel.
The form and shape of the bridge high across
the face of the dam will be seen from far down
the canyon. The aesthetic desig
was a
Figure 2: Bridge Section
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4" were provided to shadow the edge girders to give the structure a slender appearance. Form liners on the
outside of the barriers were specified for a fractured fin appearance to add interest to the structure and in
its surroundings. Modified octagonal shaped columns flare at the top to transition to the rectangular shape
of the pier caps for a sculptured look.
CONSTRUCTION CONSIDERATIONS
Steel Superstructure Erection and Transportation
s difficult. US-189 winds through the bottom
ountainsides. Shipment of curved steel girders
girders over the spillway will also be a challenge. Figure 3 shows the Framing Plan.
erection. Tall cranes
nds approximately 98 feet from each side of the spillway centerline.
at a skew, resulting in a long center span to avoid impacts to the
a construction contract for Deer Creek Dam Improvements while UDOT's
US-189 were being performed. Dam improvements required construction of a
The bridge location makes shipment and erection of girder
of Provo Canyon between the Provo River and the steep m
will be a challenge. To minimize this cost, field splice locations were chosen more to minimize girder
shipment length than proximity to dead load contra flexure points. The use of HPS 70W resulted in
lighter field sections that will ease transport to the site and girder erection. A wide girder spacing of 14'6"
was used to minimize field segments, and also to balance the large deck cantilever. Erection of the steel
Temporary roads will be needed along the face of the dam to gain access for the steel
will also be needed to reach above the 40 to 80-foot tall piers to set the steel girders.
Figure 3: Framing Plan
Existing Spillway Foundations
The existing BOR dam spillway exte
The new bridge crosses the spillway
existing spillway foundations. In the original bridge study by UDOT, consultants recommended using a
five span pre-stressed concrete bridge and rebuilding the spillway under the shorter pre-stressed girder
span. Re-building the spillway would have generated additional agreements, construction scheduling
coordination, dam spillway operation impacts, and increased cost, difficulties UDOT chose to avoid.
BOR Soldier Pile Wall
The BOR was developing
design studies for widening
50-foot high temporary soldier pile wall on the south side of the existing spillway so existing soft dam
foundation soils could be removed and replaced with stronger material. While design of the new bridge
was progressing, the soldier pile wall was moved further from the spillway to reduce wall height, and cost
of the wall. This created a conflict with the footing for Pier 3 of the bridge, which had been designed to
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resist large seismic forces at the bent. The soldier piles were to be left in place, and subsequently covered
with fill to the final grade. The location of the wall presented potential future conflicts for contractors
driving piles to construct the pier foundation.
The conflict was resolved by moving Pier 3 ten feet further from the spillway, increasing the length of
center span to 225'-0" from the original length of 215'-0". To achieve a balanced arrangement of spans
Several measures were utilized to minimize steel fabrication cost. All cross frames were designed to be
identical. A k-frame layout was u spacing to depth ratio. Top and
members are WT6x25. Bottom chord members are WT6x43.5. The major difference in
HTO Category D specifications with a horizontal acceleration of 0.5 g. To maintain an economic
n, the seismic strategy requires bearings to provide sufficient horizontal capacity during
while maintaining the same bridge length to work within available funding, abutments were shifted five
feet upstation. This successfully addressed concerns for uplift at abutments during construction and
service conditions. The reanalysis of the superstructure showed the required design changes would not
have significant impacts to the bridge cost.
STEEL DETAILING
Cross Frames
Figure 4: Intermediate K-Frame
sed for its efficiency with girder
diagonal chord
requiring a larger section was the longer unbraced length of the member. Figure 4 shows the typical cross
frame.
Seismic Details
Provo Canyon has potential for high seismic activity, and the new US-189 Bridge was designed according
to AAS
substructure desig
smaller seismic events and other service load combinations, but to fail during larger extreme event
conditions and loads. Welds connecting bearing assemblies to masonry plates are designed to act as a fuse
when loads are reached which could cause significant damage to substructure elements. The
superstructure then moves horizontally (bearing assembly sliding on masonry plate) without transferring
significant load until energy can be dissipated. A secondary mechanism is required to ensure the
superstructure does not become unseated from the substructure. Structural steel restrainer brackets are
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specified to be attached to the bottom of
girders to impact the face of pier caps and
abutments to resist longitudinal seismic forces.
Brackets are also specified to be attached to
full depth plate diaphragms at piers and
abutments. Figure 5 shows the longitudinal
keeper bracket and Figure 6 shows the keeper
blocks.
Steel Plate Transitions – Negative Moment
Regions
Fabrication of flanges with welded shop
splices can be costly. Fabrication cost can be
minimized by using the same flange thickness
for all girders and constant flange width
through each girder, so plates can be nested
together to weld plates in groups. For curved
Figure 5: Longitudinal Keeper Bracket
Figure 6: Abutment Diaphragm with Keeper Brackets
girder bridges, loads on each girder vary across the superstructure cross section, with the girder on the
exterior of the curve attracting the most load. The exterior girder will govern the thickness based on b/t
ratios for Grade HPS 70 maining girder flanges
were then sized with smaller widths based on load distributions. Bottom Flange widths varied across the
W Steel, which is a lower ratio than for Grade 50W. The re
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section from 18" to 26". UDOT also requires bottom flange width to be constant along the length of the
girder.
Weathering Steel Considerations
Weathering steel is used for the steel girders and cross frames to eliminate the need for painting and still
provide a natural color that fits well in a canyon setting. While there are significant economic advantages
materi
ond was corrosion.
835-foot radius with a 6% super-elevation and a 7% profile at the high end. Vehicles
preliminary bridge design information
pump house.
to using weathering steel, it is important to incorporate details which address the staining nature of the
al. Drip plates are specified to be attached to the bottom flange of each girder on the high side of
pier and the lower abutment. Girders terline of bearing at the abutments to
resist rusting due to possible leakage at the expansions joints. The abutment diaphragms are painted as
Figure 7: Drip Plate Details
are painted 5'-0" from the cen
well. Figure 7 shows the Drip Plate details.
DECK SLAB
The deck slab is cast-in-place reinforced concrete with epoxy-coated rebar. There were two concerns with
the deck. The first one was safety and the sec
The deck is on an
will have difficulty stopping and negotiating the curve if the deck is slippery. A requirement for an anti-
icing system was included in the contract special provisions to prevent icing and eliminate corrosion
problems associated with salting . Potential suppliers were given
and anti-icing system requirements. The suppliers submitted a concept design with estimated material and
installation costs. The anti-icing system requirements were coordinated with UDOT's IT Section and the
BOR for pump house and weather station location and system communication and control.
The anti-icing system is a fixed automated system that automatically treats the bridge deck with a liquid
anti-icing agent. The anti-icing agent is automatically sprayed on the deck based on information provided
by active and passive sensors mounted in the bridge deck along with atmospheric sensors. The system can
be activated by remote telephone using data transmission or by manual activation from the
The system is capable of dispensing varying quantities and types of liquid anti-icing agent in variable
spray sequences depending on such road surface conditions at the site as black ice, snow or freezing rain.
The anti-icing agent, potassium acetate, is non-corrosive. Its use should not affect the weathering steel
since it will be contained within the bridge roadway. A similar system is currently being used by UDOT
on the I-215 bridges at 6200 South in Salt Lake City.
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A thin bonded polymer overlay was also specified to reduce corrosion problems by sealing the concrete
deck and increase traction. The 3/8 inch overlay system provides a protective crack treatment and epoxy-
urethane polymer overlay with a broadcast aggregate wearing surface. The system consists of surface
preparation, applying a crack filling and bonding pre-treatment, and two coats of an epoxy-urethane
2004. They began driving piling for Pier 3 in March of 2005.
There are 45 HP102 piles per footing and 2 footings per pier.
ing was expected in the new and
2). After the footings were placed, the columns were formed
polymer resin broadcast with a high wear, high skid resistant aggregate that chemically cures to provide
an impervious wearing surface. The thin bonded polymer overlay is expected to extend the life of the
deck at least 10 years. UDOT has used it on many urban bridges to extend deck life and reduce
maintenance costs.
CONSTRUCTION
Ames Construction was awarded the contract in the fall of
Although very hard driv
existing dam cobble, only one out of the 90 piling driven for
Pier 3 was out of-tolerance. Pile No. 53 tilted about 7 degrees
from vertical just before it reached end bearing at about 60 feet
(See Photo 1). Pile 53 was an edge pile second from the
corner. Rather than try to straighten or pull the pile, it was cut-
off and left in place with adjustments to the footing rebar. A
review analysis showed that it could be ignored in providing
any support. Driving 90 piles for Pier 2 was completed with no
problems, although the piling were driven about 20-feet longer
than estimated from the design soil investigation. Grade 50
pilings were used for increased lateral capacity for seismic
resistance.
The 10-foot thick footings were formed, the 9'-6" diameter
column rebar cage was set and the footing reinforcement
placed prior to the concrete pours in May of 2005 (See Photo
Photo 1: Pier 3
Photo 2: Footin
g
p
our at Pier 2
Page 7 of 9
and placed. Pier 3 columns were placed to a 35-foot height
The design of the US-189 Bridge over the Deer Creek
Dam Spillway incorporated different engineering solutions
with 15' of rebar extending above to accommodate the
required seismic lap splices at the mid-height of the
columns. The column forms were made rectangular on the
outside and octagonal on the inside to conform to the
design aesthetic column shape (See Photo 3). In June
2005, the top part of the column cages for Pier 3 were set
in preparation for the forming and placement of concrete.
The Pier 3 columns will be about 80-foot tall (See Photo
4). The Pier 2 cap was being formed in July of 2005. The
pier columns are complete as shown in Photo 5. The crest
of the dam is in the background. The dam spillway is
located between Piers 2 and 3. The sculptured look of the
Pier 2 cap has taken shape with the removal of forms
shown in Photo 6.
Structural steel fabrication started in September of 2005
with erection scheduled for October. Final completion is
scheduled for November of 2006.
CONCLUSION
Photo 4: Splicing column cage
Photo 3: Partial columns
Page 8 of 9
Page 9 of 9
to build a high level bridge on a curved alignment in a cold climate area subject to adverse weather
conditions and seismic potential. The use of high performance weathering steel proved to be a practical
constructible solution. The use of simple steel details also was b ing a seismic
approach capable of being easily constructed.
EMENTS
Horizontally Curved Highway Bridges, 1993
orizontally Curved Steel Girder Highway Bridges, 2003
DOT Structures Division Design and Detailing Standards
Photo 5: Forming Pier 2 cap.
Photo 6: Pier 2 cap.
eneficial in develop
ACKNOWLEDG
Utah Department of Transportation
REFERENCES
AASHTO Standard Specifications for Bridge Design, 1996
AASHTO Guide Specifications for
AASHTO Guide Specifications for H
NCHRP Report 424
U
