Session No. 6F

Innovative Interchanges

The Innovative Interchanges session will focus unique Diverging Diamond Interchange projects that will focus on innovative solutions, current best practices, and lessons learned.

Moderator: Michael P. Mastaglio, P.E., PTOE, Urban Engineers

  • Projects at the Edge — Case Studies in Being First, Smith Siromaskul, P.E., P. Eng., Senior Transportation Engineer/ Professional Associate, HDR

This presentation will cover the life of an innovative design project from conception through planning and design to implementation.  Using the I-75 at University Parkway DDI as a core story, this presentation will also weave other projects together to provide lessons learned along the way from initial agency discussions to stakeholder outreach to design and implementation lessons learned.  It will also cover results of the operational and safety improvements seen at these location.

  • Contrasting Challenges and Solutions of Two Pennsylvania DDIs, David A. Hamlet, P.E., Vice President and Highway Section Manager, Gannett Fleming, Inc.
  • Contrasting Challenges and Solutions of Two Pennsylvania DDIs, David Kozel, P.E., senior project manager and senior associate, Gannett Fleming, Inc.

While all DDIs share many attributes and characteristics, different site constraints and project challenges affect the specific design elements of the DDI.  This presentation examines two Pennsylvania DDIs, a completed DDI in Washington County and a DDI under construction in York County. It compares the constraints and challenges experienced at both locations and describes how the solutions to these challenges resulted in both similarities and differences in the DDI design elements.

  • PennDOT DDI Peer Reviews — Lessons Learned Beyond the Guidebooks, Gilbert Chlewicki, P.E., director, Advanced Transportation Solutions

Urban Engineering with Advanced Transportation Solutions has been providing peer reviews throughout PennDOT for the past three years on roundabouts, DDIs, and other innovative intersections. The greatest value of these peer reviews arearguably lessons that can be learned from experience and the latest research that cannot be found in existing guidebooks. These reviews improve safety and operations for the project. Possibly more importantly now in times of budget constraints, these reviewscan save significant design and construction costs. This presentation will briefly touch on the various elements during these peer reviews that cannot be found in DDI guidebooks, that added value to the project.


Smith Siromaskul is a principal professional associate with HDR and leads HDR’s concept development practice group. With more than 20 years of experience split between roadway design and traffic analysis and simulation, he has been involved in the planning, design, and construction of numerous innovative intersection and interchange concepts throughout the United States, Canada, and Australia.

Dave Hamlet, P.E., is the Highway Section Group manager and a vice president in Gannett Fleming’s Camp Hill Office. He holds a bachelor’s degree from Rensselaer Polytechnic Institute and a master’s degree from Penn State. He has 28 years of experience in design and management with highway projects and is a registered Professional Engineer in Pennsylvania. Hamlet has served as the project manager on the I-83 Exit 4 Improvement Project in southern York County, Pennsylvania, which is currently in construction and scheduled to be completed in 2021.

David Kozel, P.E. is the Highway Group Manager and a Senior Project Manager in Gannett Fleming’s Pittsburgh Office.   He has over 34 years of diverse experience in the design development, management and oversight of transportation projects. David received his Bachelor’s Degree from Point Park and is a registered Professional Engineer in Pennsylvania.  He served as the Project Manager on the completed I-70/Route 19 Diverging Diamond Interchange project in Washington County, PA.


Gil Chlewicki is an internationally recognized expert and leader on DDIs and other innovative intersections and interchanges. Gil introduced the DDI concept to the transportation world in 2003 and has studied, developed, and designed DDIs for nearly 20 years, along with other innovative geometric designs.  He has given presentations and workshops, as well as assisted on DDI and other innovative designs in nearly every US state, Canada, Australia, and several European countries. 


< Back to full agenda

Thursday, December 12, 2019

3:30 to 5:00 p.m.

Room 208

Note: Select presentations are available in PDF format for download by clicking on the highlighted link for each title. If a link is not shown, the presentation was too large to be uploaded to the website.



The Transportation Engineering and Safety Conference (TESC) attracts professionals from throughout Pennsylvania, the mid-Atlantic region, and the country. It is an authoritative source of information on pressing issues from some of the foremost experts in transportation today.

Thomas D. Larson Pennsylvania Transportation Institute

201 Transportation Research Building

The Pennsylvania State University

University Park, PA 16802-4710

Phone: 814-865-1891