The original two-lane bridge (eastbound since 1973) which was opened to traffic in 1952, received a complete replacement of the roadway deck and parapets in 1986-1988 for a cost of $28.6 million (source: MDOT CTP, 1988). The eastbound bridge received a new set of paint coatings 1998-2001, at a cost of $72 million, and that included sandblasting all the old paint coatings off the steel members, including many various areas of rust. Current environmental regulations require elaborate measures to catch and dispose all the material that is removed from the bridge, with none falling into the Bay. The work could be seen underway as one drove over the bridge, especially interesting from the vantage point of the westbound bridge.
Chesapeake Bay Bridge Rehabilitation Projects
The westbound three-lane bridge opened to traffic in 1973, and is now receiving a complete deck renovation and a new set of paint coatings.
The Consolidated Transportation Program , Maryland Department of Transportation, FY2000-2005, published early 2000, laid out$206,619,000 of projects to replace the set of paint coatings on both bridges and to renovate the roadway deck on the westbound bridge, with the work to span from 1998 to 2010.
These bridges each have a shore-to-shore length of 4.3 miles. Each bridge has a suspension span over the main shipping channel, with horizontal navigational clearance of 1,500 feet, and vertical navigational clearance of 186 feet. There is a tremendous amount of steel structure in these bridges and thousands of individual steel members, hence the high cost to replace the paint coatings. All funding for the work will come from Maryland Transportation Authority (MdTA) toll revenues and toll revenue bond proceeds.
Bay Bridge Resurfacing Project, a project of the Maryland Transportation Authority (MdTA) to renovate the westbound bridge. Excerpt in November 2004 follows in blue text:
Summary and Milestones: 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.
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.
See the link for the timeline of the project's progress.
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By Scott M. Kozel, Roads to the Future
(Created 9-3-2000, updated 11-16-2004)