Using Alternative Delivery Innovation to Quickly Deliver Hundreds of Bridges 

• 558 bridges designed and constructed on an accelerated schedule.
• The first transportation P3 in Pennsylvania.
• Each bridge is designed for a 100-year lifespan.

HDR served as the lead design firm for a public-private partnership (P3) project to rapidly replace 558 bridges throughout Pennsylvania. The project was aimed at quickly cutting into the state’s backlog of about 4,500 structurally deficient bridges.

Configuration of the P3, which includes a maintenance period of 25 years, reduced the average cost to design, build and maintain each bridge from more than $2 million to about $1.6 million. The Bond Buyer, a trade magazine, awarded the project’s P3 structuring the magazine’s annual Northeast “Deal of the Year” award, in 2015.

The total project cost for design and construction was about $899 million and was executed through the concessionaire/construction joint venture of Plenary Walsh Keystone Partners (PWKP), for which we worked as the lead design firm. The Pennsylvania Department of Transportation (PennDOT) retains ownership of all bridges.

Project design commenced in January 2015 and construction started that same summer. We immediately began to draw upon our substantial design resources at 30 of our 225 locations worldwide. We completed the majority of design and permitting for the entire project in 22 months.

More than 500 HDR employees contributed to the project, as well as approximately 300 subconsultant staff. Our collective expertise reaches beyond bridge design into roadway design, hydraulics, geotechnical, traffic and utility engineering, information technology and transportation architecture. Our staff experts, many of them based in Pennsylvania, also brought experience in environmental science and the National Environmental Policy Act (NEPA), and worked with state and local agencies to obtain needed permits.

We accelerated design by delivering streamlined bridge plans that conveyed to the contractor only the information they needed to build high-quality bridges. This approach initially challenged project designers and PennDOT staff but it proved extremely successful. We coordinated bridge plans closely and planned in advance with the construction joint venture to make this efficiency possible — an efficiency necessitated by the demands of accelerated delivery — and a contributing factor to the 20 percent reduction in overall cost per bridge.

Additional delivery innovations include heavy use of standard, precast elements and structures. We were able to reduce material cost through large-scale procurement. Implementing uniform elements also reduced construction and operational costs.

Uniform Bridges with Simple but Elegant Visual Qualities

We wanted to develop an aesthetic that would fit within the parameters needed for accelerated delivery but also make each bridge easily recognizable as a part of this program. Our design team collaborated with PennDOT, other stakeholders and the construction joint venture to reconcile schedule, constructability and artistry. Through this collaboration, we developed standard inset panels on the outside faces of barriers for each bridge. This unique and consistent bridge aesthetic provided PennDOT and other stakeholders with a context-sensitive solution that could be applied statewide. 

Our collaboration with PennDOT and other stakeholders also led to the design of the program’s “signature” — a keystone emblem emblazoned on every bridge. Pennsylvania being the keystone state, the emblem connotes origin and location. Form liners for each keystone emblem also record the year in which that bridge was completed.

Seven of the 558 bridges are located in historic areas and merited heightened aesthetics. These were designated “enhanced bridges” and while each bears hallmarks of the rapid bridge program, each also has its own distinguishing architectural qualities.

Rapid Bridge Design Progress

The project celebrated completion of its 100th bridge in October 2016. The final bridge was completed in 2020.

Engaging our team’s bridge design expertise is one way PennDOT leveraged the power of alternative delivery to achieve greater value. We brought innovations such as adjusting integral abutment standards to increase the number of places they could be used; we changed approach slab criteria based on standards used in other states; and developed standard slope protection details for small fills; and we incorporated some new materials. For example, we recommended widespread use of polyester polymer concrete overlay for bridge decks, not a common practice in Pennsylvania, which protects the deck and extends its life. Several elements our team developed for the Pennsylvania Rapid Bridge Replacement Program have since been added into statewide design standard updates.

The project showcases what’s possible by embracing innovation to maximize the value of infrastructure investment. It demonstrates an approach that other owners can evaluate when facing considerable infrastructure deficiencies, limited funding and community expectations to address them sooner than later.