North-South Tollway (I-355) South Extension Aerial

North-South Tollway (I-355) South Extension 3

North-South Tollway (I-355) South Extension

Opening South Metro Access

North-South Tollway (I-355) South Extension; I-55 to 127th Street

Illinois Tollway | Dupage & Will Counties in Illinois

Crawford, Murphy & Tilly (CMT), designed the largest and, arguably, most complex section of the I-355 south extension projects, targeted to accommodate the needs of the growing south suburban communities of the Chicago metro area.

CMT developed multiple interchange/configurations, prepared an interchange design study and provided plans, specifications and cost estimates for the 2.5 mile, six-lane highway that included an interstate to interstate interchange at I-55. Interchange improvements enhanced an existing four ramp trumpet interchange making it a major eight ramp interchange with three directional flyovers. CMT completed the $170 million project design under budget and on time taking just 13 months from the official notice-to-proceed to update contract documents, prepared by CMT in 1996, to current standards. The Illinois Tollway split the project into three separate, major design/construction contracts. This section of the Tollway program represents a monumental effort of coordination of six subconsultants, five CMT offices and 12 reviewing agencies. As project managers, CMT engineers coordinated the efforts of the subconsultants, the Illinois Tollway, the Illinois Department of Transportation and the three counties touched by this project.

I would like to compliment the people involved on the engineering of the I-55 and I-355 interchange. The roadwork is fantastic. I travel that interchange many times, and I always tell my wife that it is a real piece of engineering. Thank you all for the fine work.

A Tollway Patron

Project Contact(s)

Kevin Nelson, PE

Project Service(s)

  • Construction Administration
  • Design and Construction Engineering
  • Environmental Services
  • Feasibility Studies
  • Interchange Justification
  • Lighting Design
  • Planning
  • Public Involvement Coordination
  • Roadway Design
  • Signalization Design
  • Stormwater Management
  • Structural Engineering
  • Traffic Studies, Management and Design
  • Utility Coordination