The rehabilitation project for the deck of the westbound span of the Bay Bridge consists of two phases. The Phase I contract was focused on resurfacing major portions of the bridge deck and included some full-depth poured-in-place replacement for portions of the deck. Phase II of the project, which will complete the rehabilitation of the deck, is to use full-depth pre-cast deck replacement on the suspension and thru truss portions of the bridge span.
Phase I
- Steps being taken to resolve the
"de-lamination" issue:
Numerous modifications to the original scope of work were implemented to eliminate a concrete overlay de-lamination problem. The problem was discovered in 2004 on some portions of the bridge deck where overlay, or resurfacing, work had been performed. Work modifications were provided to the Authority by a consultant who had been investigating the deck de-lamination issue since April of 2004. The Bay Bridge Overview Team, which was appointed by the Chairman, also provided guidance on the revised specifications.
The Overview Team completed their "Bay Bridge Deck Investigation" in January of 2005. Among the major changes were:
- Enhanced surface preparation methods
- New type of concrete overlay material (latex modified concrete)
- Strict adherence to weather condition requirements relating to concrete placement and curing procedures.
The left lane of the
westbound span of the bridge (lane #3) had
all the original deck overlay, or resurfacing,
work replaced during the months of September
and November 2004. Ongoing testing and inspection
of this work is underway to ensure we have
a good product. This appears to be very
successful.
Portions of the center lane resurfacing
(lane #2) that has de-laminated were resurfaced
this spring. The center lane work, included
some first-time resurfacing and full-depth
cast-in-place replacement work (original
to the Phase I scope).
The right lane (lane #1) of the original resurfacing work shows very minor concrete de-lamination at this time. Per recommendations of the Overview Team, this lane is being inspected regularly and evaluated to assure it is performing well. Maintenance and nominal repairs are routinely scheduled in this lane through the fall. Preventive deck sealing also is scheduled to continue through the fall. Ongoing patching of the portions of the bridge deck that will be replaced under Phase II will continue until Phase II work is completed.
Phase II -
rehabilitation of the remaining portions
of the bridge deck using full-depth pre-cast
deck replacement techniques. No 24/7 lane-closures
will be needed for this work:
An initial bid for the Phase II work was rejected by the Authority in January 2005. Phase II of the project was advertised in September, with a contract awarded in spring 2006 and construction starting in fall 2006. The scope and construction options to complete this phase have undergone a peer review process. The contract incorporates results of ongoing deck analysis, recommendations of the Overview Team and peer review efforts. Some of the items addressed include:
1)Modified the deck-replacement system and methodology.
2) Added full-depth replacement of more lightweight concrete spans (as recommended by the Overview Team).
3) Conducted outreach to contractors for feedback on project specifications (constructability).
4)Re-examined the MBE goals.
5)Lengthened contract duration.
Background of
Bridge and Project Scope
The Westbound William Preston Lane, Jr.
Memorial Bridge (Bay Bridge) carries three
lanes of traffic on U.S. 50 over the Chesapeake
Bay from the eastern shore of Maryland
to the state’s mainland near Sandy
Point, Maryland. The bridge was opened
to traffic in 1973 and compliments the
original two-lane bridge over the Chesapeake
Bay, which was built in 1952. The four-mile
long, 38 feet wide bridge consists of
five different types of structural components,
including pre-stressed concrete beams
at each end, steel girders, two steel
deck trusses, a three span suspension
unit, and a three span steel through truss
unit. In all, there are 122 spans (sections)
within the length of the bridge.
The Bay Bridge Deck Renovation Project
involves two deck rehabilitation methods:
resurfacing (replacing the top two inches)
and complete replacement, which includes
poured in place concrete and pre-cast
concrete segments. In addition, the roadway
joints and steel railings are being rehabilitated,
and a fiber optic conduit line has been
installed.
Late 1990’s
The original 6" to 7" thick
reinforced concrete deck at the westbound
bridge began to exhibit deterioration
that warranted initiating a major rehabilitation
program.
Contract
Design Phase (2000-2001)
An intense planning and design effort
commenced to rehabilitate the deck and
steel railing on the bridge. The Maryland
Transportation Authority, in conjunction
with several engineering consultants,
performed several detailed investigations
of the condition of the deck in order
to develop an appropriate rehabilitation
project.
A physical deck evaluation was conducted
in 2000 to determine the condition of
the concrete by taking core samples at
many representative areas on the bridge.
Data such as the percentage of sound concrete,
average concrete compressive strength,
and chloride content of each core sample
was gathered to assess the deck’s
general condition. This study supplemented
a thorough investigation of the bridge
deck performed in 1993. Both physical
deck evaluations were performed by Maryland’s
SHA Laboratory.
The consultant recommended that the concrete
deck at most (95) of the spans on the
bridge required resurfacing the top 2
inches of concrete. It was determined
the deck needed to be completely replaced
at several (27) of the larger components
on the bridge, such as the 3000 foot long
3 span suspension span unit, the entire
steel through truss, and the 3000 foot
long curved steel girder section on the
western half of the bridge.
Because of the enormity of this project,
the Authority determined that this rehabilitation
effort should be divided into two separate
construction contracts spanning over a
four-year time frame.
Contract
Procurement Phase (June 2001 – January
2002) and Contract Specifics
The first Contract was advertised in June
2001. The contract was awarded to Cianbro
on October 15, 2001. In November 20, 2001
the Authority exercised an option to add
fiber optic conduit to the contract. Execution
of the contract by Cianbro Corporation
was in December 2001, for $33.5 million.
It includes resurfacing the deck at 80
of the 92 pre-stressed concrete beam (approach)
spans, three (3) deck truss spans, and
three (3) of the 12 steel girder spans.
In addition, the deck is being fully replaced
with cast-in-place concrete in 21 spans;
all located within the pres-stressed concrete
beam and steel girder units of the bridge.
In the resurfacing portion of the project,
the contract specifications allowed for
the Contractor to select from three concrete
mix options: latex modified concrete (LMC),
micro silica concrete, or high performance
concrete.
Most of the work takes place after Labor
Day but prior to Memorial Day in order
to avoid the extremely high volume of
traffic that uses the bridge during the
summer season. The Contractor has been
permitted to close one lane continuously
for construction during the off-season
months, from approximately October 15
through April 15 each year. During nighttime
hours, a second lane or the entire bridge
has been closed in order to pour concrete
and perform other construction activities.
However, no weekend lane closures are
allowed during June, July, and August.
In addition, all three lanes on the bridge
were required to be opened to traffic
during the Easter and Thanksgiving holiday
weekends. In consideration of both maintenance
of traffic and safety of the contractors,
the travel lanes have been shifted and
their widths reduced to accommodate a
workable construction zone. A movable
concrete traffic barrier has been utilized
to facilitate lane closures and phased
construction.
As a result of these lane closure restrictions,
all the work in this project has been
constructed in three phases (i.e. one
lane at a time). A micro silica concrete
mix is being used for the overlay areas
since this material has the capability
to cure quickly in colder temperatures
than traditional concrete mixes. In addition,
the Authority required a two-year warranty
on the concrete resurfacing portion of
the project.
The current contract amount, including
approved extra work to date, is $43.5
million. The extra work includes additional
railing rehabilitation, resurfacing, and
other miscellaneous work.
Construction
Timeline
January to Spring 2002 - Work began in
the center lane of the bridge, with both
deck replacement and resurfacing operations.
Fall 2002 through Spring 2003 - Cianbro
closed the left lane of the bridge and
rehabilitated the entire deck within the
entire contract limits.
Spring and Fall months in 2003 - The contractor
performed extra work to resurface more
than 4000 feet of the deck (9 spans of
deck truss) between the two channel spans.
Fall 2003 through Spring 2004 - Cianbro
closed the right lane of the bridge and
rehabilitated the entire deck within the
entire contract limits.
Work remains to be completed in the center
lane, including some overlay, joint replacements,
and deck replacement.
Resurfacing
Problems - Timeline
December, 2003 – Construction inspectors
identified random, isolated concrete cracking
in the deck.
February to March, 2004 – Construction
inspectors noticed increased areas and
amounts of concrete cracking in the deck.
Spring 2004 – Construction inspectors
noticed widespread concrete cracking in
the deck, contained in the center and
left lanes of the bridge. Construction
personnel documented the extent of the
deterioration.
March 2004 through Present - The consulting
firm of O’Connell and Lawrence, Inc.
(OC&L) was contracted to perform an
independent investigation regarding the
concrete cracking conditions in regards
to the actual cause as well as appropriate
solutions to remedy the problems. A task
order for this work began in April. OC&L
has performed field and laboratory testing
on the concrete deck in the left lane.
Meetings amongst the Authority, OC&L,
the original design consultant, and the
contractor began in March and have continued
to date.
Other Investigative Work and Reports conducted
and performed by OC&L:
- Over 370 small concrete "cores"(samples)
have been extracted from the deck of lane
3. Laboratory tests have been conducted
on these samples in an effort to ascertain
the possible causes and failure mode of
the concrete.
- Test "patching" sections have
been performed on the deck in order to
provide more information regarding appropriate
surface preparation methods to use prior
to placing a new concrete material over
the existing deck.
- June, 2004 - Initial findings of concrete
cracking in deck submitted to Authority
- August 18 and 20, 2004 - OC&L submitted
letter to Authority with preliminary recommendations
of the use of LMC as well as a more intensive
surface preparation method for future
overlay work.
- September 2, 2004 – The Authority
Capital Committee was briefed. They requested
repairs begin immediately with LMC and
that weekend closures be utilized if it
proved necessary to complete the work.
- September 3, 2004 – OC&L submitted
Preliminary Report of Findings to the
Authority.
Other
Developments
September 10, 2004 – A peer review
panel consisting of Authority, SHA, Virginia
Transportation Research Council, and OC&L
personnel convened and concurred with
findings of the Preliminary Report.
September 10, 2004 - A press release was
issued stating that the left lane of the
bridge will be closed continuously until
November 24 (Wednesday before Thanksgiving).
September 13, 2004 – Contractor closed
the left lane of bridge with concrete
barriers, to mill (scrape) 2 inches off
the top surface of deck, perform surface
preparation procedures as recommended
by OC&L. Cianbro contracts GA &
FC Wagman, Inc. to perform LMC (latex
modified concrete) overlay placement operations,
which would take place after the deck
surface has been adequately milled and
the surface has been prepared.
September 20, 2004 – Baltimore Sun
contacted Authority inquiring about the
lane closures and the resurfacing issue.
For current
conditions at the bridge 24 hours-a-day,
contact the BAYSPAN hotline at 1-877-229-7726,
or Click
here to view real-time camera images
from the bridge’s approaches
