Transcript AASHTO Sub-committee on Design_combined

AASHTO Sub-Committee on
Design Meeting
April 28, 2010
The historic Ben Sawyer Bridge was built in 1945 to
carry locals and visitors between the east cooper
barrier islands of Sullivan’s Island and Isle of Palms
with Mount Pleasant and the rest of the Charleston
area. For years, it was the only vehicular access for
both Sullivan’s Island and the neighboring Isle of
Palms. The Isle of Palms Connector was completed
in 1993 and provided additional access to both
Sullivan’s Island and the Isle of Palms.
The Ben Sawyer Bridge drew significant national
attention when Hurricane Hugo came ashore in the
Charleston area in 1989. The storm essentially
picked up and rotated the swing span, leaving it
tilted at a 45-degree angle, which created one of the
lasting images of the hurricane’s devastation. The
swing span was lifted back into place on October 5,
1989. One lane of the bridge was re-opened to traffic
on October 8, 1989.
Traffic Congestion
 Traditional construction requires a 12-month, 11-mile detour
through the Isle of Palms and Mt. Pleasant.
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ABC requires a 10-day detour.
 ABC avoids approximately 12 months of additional traffic
congestion in both the Town of Mt. Pleasant and the Isle of Palms.
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ABC reduces crash potential.
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ABC reduces motor user costs.
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ABC provides much greater access to both Sullivan’s Island and
the Isle of Palms.
Quality of Work
 ABC improves the quality of work by constructing the swing
span in an off-site controlled atmosphere.
 The use of ABC further improves the quality by having the
majority of the swing span’s electrical and mechanical
components installed off-site as well.
 Preliminary functional testing can be completed off-site
without interference of the motoring public.
Marine Traffic
 ABC has much less impact to the intra-coastal waterway and
its’ users.
Project Duration – 540 days
Liquidated Damages - $2,900/day over 540 Days
DBE Goal – 5%
5-Year project warranty
Warranty Bond ($5 Million)
Professional Liability Insurance ($3 Million)
Duration – 10 days for Total Closure
Closure Restrictions –
Prohibited between April 1st and October 1st.
Prohibited between December 15th and January 3rd.
Incentive Pay - $2,500/hour up to 48 hours.
Disincentive - $2,500/hour over 10 days with no cap.
Swing Span fully operational
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Contractor – PCL Civil Constructors, Inc.
Construction Manager – PB Americas, Inc.
Designer – Hardesty & Hanover, LLP
Owner – SCDOT
FHWA – 100% oversight project
Roller System
April 28, 2010
April 28, 2010
Old Swing Span being removed
New Swing Span ready for placement
New Swing Span being placed
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April 29, 2010 cracks in the webs of steel plate girders were found by the District 4
Bridge Inspection Team at I-77 NB and SB over S-12-56 in Chester County
Bridge Maintenance Office verified the severity of this condition, which did not
exist as of the previous normal inspections 2 years ago
It is believed that the primary causes for the cracked girders on I-77 are the
following:
 thin web plates (<1/2”), these were 3/8”
 diaphragm and stiffener web plates were only welded to the web and top flange thus causing an
inordinate amount of torsion to be carried more directly by the web
No weld
Weld
Diaphragm
s offset
due to
skew
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Other factors contributing to the cracking were:
 bridge skew
 torsional fatigue and possible overall fatigue
 possible overheating of the steel substrate due to multiple weld passes on the web to flange
connection during fabrication
 material mechanical properties (to be verified by testing)
 construction loadings during I-77 construction could have reduced the fatigue life
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Emergency Declaration was approved by SCDOT
Secretary of Transportation Limehouse on May 3, 2010
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met two qualified bridge contractors on site May 4, who were given information that required the contractors
to bid on temporarily shoring and replacing both steel plate girder main spans
 District 4 closed the ramps and overpass/S-12-56 on May 5, 2010 and began work to improve the on and off
ramps which were used for the detour
 Bids were received on May 10, 2010 and an accelerated contract cost and schedule was negotiated on May
11, 2010 with the project low bidder, United Contractors
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Temporary shoring was
installed beginning May 12,
2010 to allow traffic to
continue using the bridges
until closed for work
Temporary Shoring
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Bridges were closed on June 7, 2010 and demolition of the main
spans began.
New girders were set beginning June 11, 2010
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Deck pours started midweek of June 14, 2010
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Both spans were completed by June 28, 2010
Bridge Maintenance performed a project final inspection on June
28, 2010
Bridges were opened 2 days later on June 30, 2010
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Ramps were reopened for normal use on July 23, 2010
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Interstate Rehabilitation of I-385, approximately 15 miles, with
10” of high strength concrete
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Raising of 6 overpass bridges
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Bridge replacement of fly-over bridge
that connects I-26 westbound to I-385 northbound
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Shoulder widening with roller
compacted concrete
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I-385 northbound detoured; construction duration condensed
from 3 years to 7 ½ months
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Northbound Detour
 Relatively low ADT (17,600 to 21,900) within project corridor
 Existing pavement width (32’) insufficient to stage or run head to
head traffic
 Parallel interstate in close proximity for detour traffic (15 mi./15 min.)
 Good network of regional primary routes for local traffic
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Detour Benefits
 Safety increased by separating motorists from construction
operations
 Construction operations streamlined with closure; allowed
pavement of full width PCC up to one mile per day (weather
permitting)
 Estimated $34.6 million in savings compared to traditional
construction staging over multiple years
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Affected businesses, elected officials, and state trucking
association contacted months prior to closure
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Brochures and maps were distributed at local Rest Areas and
project website was established with detour information
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Contractor was required to hold Public Information Meeting
prior to closure
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Pre-construction and mid-construction partnering meetings
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Contract had $25,000 daily incentives not to exceed
$750,000 and $50,000 daily liquidated damages with no cap
beginning August 16, 2010
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Bridge jackings were let in separate contract and completed
prior to I-385 northbound closure
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Project let five months in advance of closure date for prep
work and material fabrication (fly-over bridge superstructure)
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All excavation was converted to Site Excavation
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Concrete paving machine guided by laser total station with an
automatic dowel inserter
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Leica Scan Station 2 survey scanner used to verify crossslope correction