Constructing a Missing Interstate Link in Downtown Pittsburgh
By Glenn D. Stickel, PE
Project Manager, SAI Consulting Engineers, Inc.
When the Fort Duquesne Bridge over the Allegheny River was opened in 1968, traffic flow from points north of Pittsburgh was greatly improved. Motorists now had convenient access to downtown Pittsburgh and the Fort Pitt Bridge. However, to connect to I-376 East (know locally as the Parkway East), vehicles were forced to use a local street (Fort Pitt Boulevard Eastbound) and negotiate a series of 3 signalized intersections.
The demand on Fort Pitt Boulevard increased to over 15,000 ADT with the connection of I-279 Southbound to the Fort Duquesne Bridge in 1985. Traffic flow was then compounded in the mid 1990’s when the right lane of the Fort Pitt Boulevard viaduct was closed due to structural deterioration, reducing the 3-lane cartway to 2 lanes.
City of Pittsburgh officials were faced with the burden of an aging, deteriorating structure that played an important role in the traffic network in the Mon Wharf corridor. Through a collaborative effort between City and PennDOT engineers and planners, a creative solution was developed --- reconstruct the Fort Pitt Boulevard viaduct in such a way as to provide a dedicated interstate lane, separated from local traffic. Thus, traffic from I-279 and the Fort Duquesne Bridge could access I-376 eastbound unimpeded by traffic signals and weaving with downtown traffic.
Once the decision was made to proceed with the “Interstate Connector” project, the focus turned towards planning and scheduling. PennDOT was already in the process of reconstructing the nearby Fort Pitt Bridge. It was ultimately decided to phase the Fort Pitt Boulevard/Interstate Connector project within the framework of the Fort Pitt Bridge timetable.
The two main stages of the Fort Pitt Bridge project were scheduled to occur in 2002 and 2003. It was decided to reconstruct Fort Pitt Boulevard in 2002, concurrent with the “outbound” portion of the Fort Pitt Bridge, so that the newly constructed Interstate Connector would be available as part of the detour route for “inbound” Fort Pitt Bridge traffic in 2003.
In 2000, the City of Pittsburgh selected a final design team lead by prime consultant SAI Consulting Engineers, with key assistance from Michael Baker Jr., Inc., and final design began in November of that year. To take full advantage of the available calendar time in 2001 (for design) and 2002 (for construction) it was decided to bid the construction phase as two contracts.
A demolition contract was bid in October 2001. The contractor, GASA, Inc., removed the superstructure and portions of the substructure on the main viaduct as well as the adjacent Market St. Bridge. Work began in January 2002 and was completed by April 2002, thus providing a clear site for the second contractor to immediately begin foundation construction.
The second construction contract was bid on February 28, 2002 and was awarded to Brayman Construction Corp. Construction began April 29, 2002.
Due to the importance of completing this project with respect to the second season of the Fort Pitt Bridge project, the contractor was required to meet a series of six milestone dates.
Innovative Bidding was utilized. The AA-B Method@ (a modified version of the usual A+B method) allowed the bidders to present a time factor in addition to price. Selection of the low bidder was based on the dollar amount of the bid (A) minus the time factor (B).
Incentive/Disincentive provisions were also included in the contract. For four of the milestones (1, 4, 5 and 6) the contractor was entitled to earn an incentive for each day of early completion (with a maximum of 15 days each); conversely, disincentives would be charged for each day of late completion. Brayman successfully completed each milestone by the maximum early completion date, thus earning the full incentive.
This project involved the reconstruction and/or rehabilitation of seven bridges (including the 1900' main viaduct), one retaining wall and one tunnel, along with associated improvements to the adjacent approach roadways. The construction cost was in excess of $34 million ($2.67 million for the demolition contract and approximately $31.5 million for the reconstruction contract).
The focal point of the project was reconstruction of the 1940-vintage Fort Pitt Boulevard Eastbound viaduct. Originally a 37-span structure that terminated at Smithfield St., it was rebuilt as a 35-span bridge that now passes beneath the Smithfield St. Bridge. The original cartway had three lanes of traffic and one sidewalk. On the reconstructed deck, traffic has been separated to provide a dedicated Athrough lane@ that creates direct access from I-279 Southbound (from the Fort Duquesne Bridge) to I-376 Eastbound, and two lanes of local traffic. To accommodate the local traffic connection to the Smithfield St. Bridge and points east, a new 3-span bridge was constructed from Wood St. to Smithfield St.
Reconstruction of the piers was a significant structural aspect of the project. The original 2-column concrete piers were modified by removing the concrete cap, constructing a new center column (slightly offset from the centerline, to allow parking operations below) and a new concrete cap (supported on the original columns with pot bearings and rigidly attached to the new column, to attract more load to the new foundations).
Also included was the rehabilitation of the adjacent Stanwix St., Wood St. and Ramp B bridges and the three north approach spans of the Smithfield St. Bridge. The adjacent Market St. Bridge was replaced. The 2400= concrete retaining wall supporting Fort Pitt Boulevard Westbound above I-376 Westbound (Wall AA@) was repaired.
Context Sensitive Design was implemented in several elements of the project, including Vierendeel trusses for the sign structures; selective paint colors for sign structures, light poles, bridge girders and steel handrails; and the use of open-type bridge parapets.
To celebrate the completion of construction, two opening ceremonies were held. PennDOT opened the Interstate Connector on December 6, 2002 and on December 17, 2002 the City of Pittsburgh conducted a ribbon-cutting to mark the opening of the reconstructed Fort Pitt Boulevard Eastbound.
A tremendous amount of design and construction was performed in slightly more than two years. Despite the accelerated schedule, this $34 million endeavor was successfully completed in a high quality manner.
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