Projects

The Fort Pitt Bridge and Tunnel is the "Gateway to Pittsburgh," not only for the legendary view of the city that opens up from the tunnel portal, but also for its true function as a primary transportation link to the Pittsburgh's Central Business District.

On any given day, 150,000 vehicles use the bridge and tunnel to access the city, making it the most heavily traveled facility in Western Pennsylvania and an influence on the people and economy of the region that cannot be understated. So when the 1950s era structures started showing their age with corrosion, cracking and dangerous deterioration, the Pennsylvania Department of Transportation (PENNDOT) was faced with the daunting task of rehabilitation. The "nuts-and-bolts" of the project included the rehabilitation of dual 3,600-foot-long tunnels, a double-deck 750-foot tied arch river span, and a "spaghetti-bowl" of ramp structures in excess of 7,450 feet in length. The project also shouldered the concerns of the residents of the region and the health of the local economy.

As the project got underway in 1991, there were predictions of an impending disaster for the Pittsburgh business district and a traffic nightmare throughout the region. In 2003, twelve years and seven construction contracts later, the rehabilitation was completed with far less disruption to the public and economic loss to the community than ever thought possible in 1991. The last contract was a two-year rehabilitation of the tunnel and river bridge. This contract limited closure of the tunnel and river bridge to only four months in each direction, an unprecedented schedule that was considered unrealistic by project opponents. The budgeted cost for this project was $84,247,000; the actual cost was $81,597,000. The scheduled completion date was October 31, 2003; the actual completion date was September 30, 2003.

PENNDOT entrusted the rehabilitation of these facilities to a team assembled by HDR. As the prime consultant, HDR led the design team and performed bridge, roadway/civil and geotechnical design for the project. Innovations developed by the design team included:

Unusual pier repairs under traffic. Several mainline piers were so deteriorated that their rehabilitation could not wait. HDR prepared plans for the emergency repair of five piers that included the innovative approach of jacking the structures on a heavily traveled urban interstate. This limited the impact to the traveling public, which had little awareness of this work.

Innovative new "Pennsylvania" bridge barrier. The standard traffic barrier obscured the spectacular view from the bridge significantly, and community groups argued that the view must be preserved. A collaborative effort was undertaken to design a new, more open barrier that would still provide the required strength. HDR completed the design, obtained FHWA approval and prepared the plans for the new “Pennsylvania” barrier, which was used on the all-important upper deck and has received wide acclaim, winning the 2003 AIA Component Excellence Award.

Time-saving precast pier caps. The original 2,600-foot-long I-376 eastbound ramp - especially its concrete piers - was badly deteriorated from exposure to deicing salts. It connects two interstate roadways and needed to be replaced quickly. The existing structure was demolished above the footings and the existing footings were reused with new cast-in-place columns. Unique precast pier caps were then set on the columns and grouted in place. Demolition and reconstruction were completed in an unprecedented six months.

Unique lane rental concept. This creative contract condition motivated the contractor to open travel lanes as quickly as possible. The contractor “rented” travel lanes from PENNDOT based on road user costs. The contractor was given some discretion to determine how many lanes would be closed during construction.

State-of-the-art tunnel control system. Rehabilitation of the tunnels included a complete upgrade of the monitoring and communication systems. Power distribution, ventilation, fire alarms, surveillance, lighting control and over-height truck detection systems are now monitored and controlled from a single integrated computerized system developed exclusively for the Fort Pitt Tunnels. Tunnel lighting can be set to automatically respond to changes in the outside ambient lighting. Closed circuit cameras installed throughout the tunnels provide personnel constant monitoring capabilities allowing them to provide quick and appropriate responses to emergency situations.

Directional staging. Because traffic modeling showed that complete closure of the bridge and tunnel was not feasible due to the negative impacts on traffic citywide, directional staging was the preferred solution. The outbound lower deck of the bridge and the associated tunnel were done in 2002 and the inbound upper deck of the bridge and its tunnel in 2003. HDR's subconsultant PEC, working with the Department’s traffic unit, fine-tuned the detour routes for each season in order to minimize impacts to the traveling public.

Aesthetics. This facility is undoubtedly the most recognizable bridge in "The City of Bridges." The new Pennsylvania Barrier was developed with community partnering. Special sign structures were used to match the theme of the central business district of Pittsburgh. Tunnel lighting was made bright for safety and for an aesthetic appearance. New concrete abutments were patterned to match the original granite facing panels.

Creative engineering, integrated scheduling and effective teamwork helped avert this potential disaster for businesses and the motoring public. HDR's team, working in partnership with PENNDOT and regional construction contractors, delivered the largest single rehabilitation project ever undertaken in Western Pennsylvania, ahead of schedule and with minimal disruption to business and the public, while developing several innovative technical solutions that will impact future projects for years to come.